Week 13 Digital workflow & Lightroom

This week we will be learning about:

• Finishing off personal studio portraiture
• Discussing digital workflow

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Organising Your Digital Imaging Workflow

Having a clear framework for digital image production, editing and output is vital for photographers to be able to organise, archive and locate their images day to day, month to month and year to year. You don’t want to waste time doing basic image editing and admin tasks that could be automated in a simple and effective workflow that starts with downloading your photos from your camera…

There are many software applications that are designed to help you organise, catalogue and edit your digital images. Some have professional spec image development tools whilst others are primarily intended for cataloguing and organising files and folders as a “photo library” or archive.

One of the most popular free applications is “Picasa” from Google which is free to download and includes basic image editing tools but is a powerful cataloguing application and organises your images into folders easily. Other applications are more powerful but also more expensive. Adobe Lightroom is fast becoming the industry standard application for many professional photographers and most of what follows is based on Lightroom…

 

STEP 1: Up-load your images from camera to computer

By using a decent image editing package like Apple’s Aperture, Adobe Lightroom, Photoshop (Elements or CS) or possibly even the OEM package that shipped with your camera, you can quickly edit, do fast post-production and do captioning  and key-wording even as your images are being imported onto your computer.

Here at Kendal College, we use (and recommend) Lightroom (the current version is v4). Because that is what I use, I’m going to base the rest of this conversation around my workflow in Lightroom. You may not have Lightroom and you may have a different approach to your workflow. That’s fine – whatever works for you is OK. I’m just going to outline my approach and you can take from it what you will.

So, This is how I do it:

Connect camera or CF card reader to computer

I use a CF card plugged into a dedicated card reader connected to iMac via USB cable. Import dialogue opens in Lightroom. This allows many options to be used.

Import to Hard Drives. 

Ideally you will have two external hard drives, mirror images of each other. Hard drives are cheap and robust and you can buy them easily in pairs. 750Gb to 1Tb capacity drives will be sufficient for most people. You can also set up a simple software program that copies any changes that occur on drive A to drive B so now you have a main external hard drive, safe from virus attack and corruption problems and a back-up hard drive that mirrors your main hard drive and provides a complete back-up of all your photos. Do not keep your photos on your main computer (they take up too much room and can get corrupted too easily) particularly if it’s a laptop – very easy to loose or have stolen! Incidentally, using cd or dvd as a backup is OK in the short term but unwise long-term as these discs have a shelf life and can become unreadable after as little as 3 or 4 years. Lightroom also gives me the option to create a complete back-up of the import on my C-drive just in case. I always use this and then delete the back-ups once a month or so when I’m confident I have everything safely stored and backed-up on my external drives.

Specify a location and re-name your photos.

Now is the time to decide where you are going to store your images. If you are organised you will have sorted out a file and folder system or date order system for storing your photos. If you have not and your images are being stored in a random order, scattered throughout your computer, you need to address this right now! You are building a photo “library” and it needs to be as organised as a book library otherwise, years from now you will struggle to find your photos when you need to. Specify where your photos will be imported to and re-name them with whatever file/folder naming convention that you are using.

Keywording:

Insert the global keywords that are relevant to all the images that are being imported, but not keywords that are specific to individual images, we do these later. For example, a photo of the Langdale Pikes would use “Cumbria”, “Lake District”, “Langdale”, “mountain”, “landscape” as global keywords that would be relevant to any images that included the Langdale Pikes. Keywords are vital, they are the reference system that you and your editors will use to locate specific images both now and in the future, amongst thousands of other images that you may have on your or their systems.

Captions. If all the images are the same subject you can also give the images a global “caption” which is the explanatory sentence that tells us what the image is all about. If the images are a variety of subjects you may choose to do some of the captions now and some or all individually, later on.

Metadata. You can also add your personal metadata to your images as they are imported. Metadata is information that is appended to the photo’s sidecar file and travels with the photo whenever you import or export it. You can normally specify metadata that includes your name, contact details, copyright information and other specifics that you wish. All your photos should include personal metadata that helps you and others to track and identify your work where-ever it is used, so it’s as important as putting your name on your written texts.

Image developing options in the import dialogue. If you shoot Jpeg images, the files should ideally come out of the camera ready to use and should not require very much in the way of image developing or post-production – that’s what Jpegs are designed for. However, if you shoot RAW then all of the image developing still needs to be done and often you can do most of this in one go as the images are being imported. A program like Lightroom allows you to use pre-set image developing settings that can be applied to all images as they are being imported, which means that you have only a few tweaks to make after the images are imported.

Import your photos:

Once you have selected the source and the destination, given the destination folder an appropriate name if necessary, set the re-name files option if required, done the globalkeywords, global captions and global image processing that you want and you’ve appended any metadata files you’ve set up, your ready to hit the import button. But there’s nothing here that you can do wrong – if you make a mistake in Lightroom with just about any option, you can undo it or revise it at any time, which is why the software is so good to use.

So I now go ahead and hit Import Images.  All my images should download from my memory card into the right file, in the right folder, with correct file names, keywords and captions, with metadata and with develop settings already done. That saves me a load of work later on.

STEP 2: Editing your photos

If you have organised your workflow in this manner so far, you should have a straightforward job of editing now. You need to zip through each image and decide which are “keepers” and which are “trash”. Be ruthless and get rid of the failed images as fast as you can! Then you can concentrate on the images that are worthwhile.

When you have edited your collection down to the keepers, you can go through and tweak the developing. Each image will need to have its’ histogram examined and small exposure changes applied to maximize the tonal range or get the “look” that you want.

Lightroom gives me a number of options and ways of tagging or flagging images when I’m editing, so I can give them ratings or organise them into groups according to my needs. First I can flag them as picks, un-flagged or rejects. I start by just using pick (P) or reject (X). When I’ve been through the lot, I hit Cmd Delete and delete all the rejects (X’s) off my system. I’m pretty ruthless about this and once I’ve made the decision to mark a shot as rejected I almost never change my mind, hence the deletion. If I do decide I’ve made a mistake at a later date, all is not lost. I still have that backup of the original download on my C-drive that I can access to re-instate the image if I need to. Once I’ve deleted all the initial rejects, I go through the shoot again, this time with a more critical eye. I’m looking to downgrade as many of the images as possible to “un-flagged” status or find images that ought to be rejected but were missed first time around. What I should end up with is an elite collection of Pick images from the shoot and a whole bunch of un-flagged “nearly-but-not-quite” shots that will do for extra stock. What I hope is that I will have got rid of all the sub-standard stuff by now – never have to look at them again!

STEP 3: Post Production

Now it’s time to fine-tune the Picks. I don’t bother with the un-flagged shots until I have to actually use them.

Cropping. It makes sense to take care of any cropping of the image first so you don’t waste time trying to do post production on areas of the image that are going to get cropped out. At the same time, you can do image rotation if the horizon or vertical lines need adjusting and if you have the tools (Lightroom does), you can also fix convergence or divergence.

Histograms. For most images that contain a range of tones from deep shadow to bright highlight, the histogram should be contained within the black point and the white point. In fact many photo-libraries will specify that images submitted to them should be contained within the tonal range of 2-254. What does that mean? Well, absolute black in a digital photo is described as tone 0 and there are 256 tones represented on a camera’s histogram, tone 256 is absolute white. Mid grey – mid tone – is halfway between these two extremes at 128. Any tone that is darker than mid grey will have a value of between 128 and 0, whilst any tone lighter than mid tone will be 128 -256.

If you produce a photo in which the histogram displays a range of tones that start at about 2 (almost black) and finish at about 254 (almost white), you will have captured very nearly the full range of tones possible without actually reducing your darkest tone to black or your lightest tone to white, which means you will have some detail in the shadows and some detail in the highlights – and that’s what photo-libraries want.

Of course, sometimes your photos will need to have black or white in them – a silhouette for example, will by definition contain lots of black – tone 0. But if your photo looks like it ought to contain a full range of tones, tweak the exposure controls to make your histogram fit between the black point and the white point. Over-running the black or white point is called “clipping” and is normally to be avoided.

Fixing exposure problems. Most exposure problems, errors in which the exposure has been slightly over or under cooked, can be fixed just using exposure, contrast, and colour balance controls and don’t require a lot of post-production work. Generally, the less you do the better and if you are shooting Jpegs you really don’t want to be pushing the digital image very far at all – doing so can very quickly result in a very degraded photo.

White balance. Again Jpegs should have their white balance fixed in the camera at the point of shooting. Although Jpeg white balance can be fixed in Photoshop or similar using the colour balance controls, it requires a bit of fiddling and an understanding of how RGB and CMY colours work together. RAW files however can be white balanced very easily in any raw converter software with a simple slider control. It’s one of the reasons why RAW is preferred by photographers. White balance refers to how cameras treat colours under different coloured light sources.

If you didn’t already know, daylight is “blue’ish” light and it’s how we normally perceive colours. But household lights are tungsten, which are orange in colour. Clearly, to a camera, colours illuminated by blue light will look very different to colours illuminated by orange light, hence the need for white balance. Auto white balance controls on cameras usually work well, but not always, so when shooting Jpegs, be prepared to set manual white balance in the camera.

Colour balance. Fixing colour balance is really about looking for colour casts that shouldn’t be there, or returning coloured areas to a more natural state. Greens and blues for example can acquire colour cast that make them look wrong; Greens ca sometimes look too yellow or magenta whilst blue skies can tend towards magenta or purple. Skin tones in portraits are worth looking out for as well – they can look too green or blue. Tweaking the colour saturation or better still the colour vibrance controls can help a lot.

Noise & Dust. Once your photo is looking healthy and natural you will want to check it for noise and for dust marks. Noise is a product of high ISO values, small sized digital sensors and over or under exposure leading to loss of high light or shadow detail and speckling. Compact and “bridge” cameras always exhibit more noise than DSLR’s, Dx DSLR’s often show more noise than Fx or full frame DSLR’s. Most decent image editing programs have filters to allow you to attempt to hide or disguise any obvious signs of noise with a simple slider control.

Another type of noise is “edge” or “colour” fringing which is seen as a coloured band or fringe along the edges of high-lights, often purple or blue in colour. Again, a good tool like Lightroom will detect these edges and allow you to dial them out with a slider control.

Dust is a major problem on digital cameras, particularly DSLR’s where the sensor is more exposed during lens changing and so on. The only reliable way to spot dust marks is by examining your images at 100% scale on the monitor. You will see the dust marks as dark spots or splodges in areas of continuous light tone – typically the sky or areas of water. They don’t tend to show up in areas of dark detail so much.

To get rid of them you should use the “healing” tool in your image editing software – occasionally the “clone” tool will be more appropriate And if there are a lot of dust marks, clean your camera sensor with an approved swab and sensor cleaning product. However, do not be tempted to use canned compressed air – the propellant used in these products will ruin your sensor!

STEP 4: Fine tuning in post production

Lightroom has some powerful post production tools, like its’ ND Grad filters, dodge and burn tools, anti-red eye tool and so on. It also has a lot of creative “pre-set filters” for black and white, sepia or colour masking and it has other tools too. Thee are tools you use with discretion but it’s your choice when and how to use them. I find that I use the ND Grad tool all the time!

Here’s a landscape (Langdale Pikes) that I’ve been working on, using the ND Grad tool to really bring out the sky detail and create some extra shadow drama! I can also open the image in Photoshop, direct from Lightroom, complete with Lightroom changes applied, if I want to, in order to do re-touching work using layers which Lightroom doesn’t have. Lightroom and Photoshop work seamlessly in this way.

STEP 5: Ready to export

In Lightroom you don’t need to export your images to save them, they are already saved and can be closed when you have applied all the post production. However, at some stage you will want to send them to a printer, or email them or upload them to a website. This is when you will need to export…

Different destinations will have different requirements for outputting your photos. A publisher will need a different kind of file to a print house or photo-finishing lab and your ink jet printer will need something different again.

Website and email applications need low res images at 72 ppi (dpi) whereas an ink jet will want something between 150 and 270 ppi. A publisher will want 300 ppi.

Sending your images to be published?

This is the spec you would output to for a magazine or publisher:

• JPEG (standard Jpeg, not Jpeg 2000)
• 300dpi (ppi)
• sRGB colour space (not Adobe RGB)
• 100% JPEG quality setting.

What is dpi?

•  Dpi is Dots per Inch and refers to how many dots of ink per inch a printer needs to render an image at photographic quality. It has nothing to do with the quality or resolution of your photo. That is controlled by how many pixels you have in the image. So ppi is how many pixels per inch the printer will be printing onto paper. The more pixels you have, the more of them can be printed per inch, so the higher the quality of the print. So dpi and ppi tend to be used interchangeably. But they have nothing to do with the quality of your image. If you are changing/upsizing the dpi/ppi setting in your software, make sure you have “resample image” turned OFF, and if have a setting that says “maintain original size”, make sure this is checked ON otherwise the software will try to resize your image to meet these printing requirements and result in a very poor quality file. As a rule, just set your dpi/ppi settings to 300dpi for publication and 72 dpi for web use.

• Pixel dimensions. The quality of your photo is determined by the amount of pixels you have, amongst other things. A typical 6 megapixel DSLR like a Nikon D40 produces a file that is 2000 pxls by 3000pxls. If I want a print 10 inches wide I divide 2000 by 10 and get a figure of 200 pixels per inch of print and 3000 divided by 200 equals 15 so my print is 10 inches wide by 15 inches high at 200 ppi. This is perfect for a high quality print. So when an editor asks for a specific pixel dimension (say, 3500 pixels on the long edge) what he’s really saying is that if you send a file that contains that many pixels he can be sure he can make a print that is at least 15 inches wide and that’s big enough for anyone!

• File Size. Often we are asked for specific file sizes or file sizes not exceeding a certain size. This is because either it won’t be accepted as email or it’s too big for the ftp client to handle or some other reason. It’s easy to compress Jpegs to fit a given file size, it just takes a couple of trial runs with different levels of compression to check the compressed file size meets the requirement. A 12 megapix camera will make a 28mb jpeg which will produce an 8mb file when compressed at maximum quality setting 10 or 12. Reduce the compression to 35% and you get 1.5mb file, which will still open to a 28mb file when full sized.

• Colour space. There are a number of “colour spaces” that a digital file can be saved in but typically we only talk about two of them – AdobeRGB and sRGB. From the point of view of publishing images, set your camera to sRGB and export your images as sRGB. Don’t use Adobe RGB unless you really have a good reason for doing so. AdobeRGB files print very flat and dull, sRGB files print much better, full of contrast and colour. It’s also harder for a printer to muck up your colours in sRGB!

• 8 bit files. Most RAW digital files come out of the camera as 12 bit files but are can be processed as 16 bit files. However, when you convert them back to 8 bit files you halve the file size – which is good! Only send 8 bit files, there’s no benefit in doing otherwise, unless you are sending files to a graphic designer who is going to do a lot of post-production with them. Jpegs are already 8 bit.

• In Lightroom, when I export my image files, I can select from pull-down menus all the parameters that I want for the files that I’ve selected to export. It doesn’t change the image file in any way. It just applies these parameters to a copy of the image file which it creates and exports with these changes and settings. The original files are untouched. I generally use the following settings to create a high res file for publishing:

• 8 bit, sRGB, 300dpi, 100% Jpeg, original size, with medium output sharpening applied, saved to a named folder in My Pictures or to another destination, complete with My Metadata, an image caption and full keywording.
• If I’m exporting for email or web, I use 8bit, sRGB 72dpi, 50% Jpeg, with high sharpening for screen applied and saved to whatever folder I’ve specified.
• Lightroom actually enables me to make any number of pre-sets for saving images to specific or regular destinations or target settings and I use this facility a lot.

STEP 6: Alternative ways or delivering an image

• On Disc – cd or dvd
• Via FTP
• Email
• Web client (Photoshelter)

Delivering images to an editor or publisher, at speed to meet deadlines, can be made very simple. Here’s some solutions.

 

1. Burning the image files onto disc. This is universal and easy to do. But there’s a couple of things to point out. Some disc drives don’t like cd’s, some don’t like dvd’s and the quality of discs can be variable. Just because you can read the files on a disc doesn’t mean the client at the other end can. So use good quality discs. You should always include a file that contains your contact and copyright information and always label your discs clearly with your name and contact details because discs are easily misplaced, lost, left lying around in offices and generally misused! I never send images on disc if I can help it!
2. FTP. This is better. It’s quick, efficient and safe if the client has a dedicated ftp server. You can use free ftp clients like Mozilla’s “Filezilla” which is a free download or if you use Mac as I do, use Fetch which is excellent. You can also use third party ftp websites like “yousendit” and “mailbigfile” – they work very well.
3. Email. If you can email the client your images then great! It’s easy and safe and costs you nothing.
4. Web client. This is what I use. I have a Photoshelter account that allows me to upload large numbers of images, make galleries and invite clients to view the galleries. It allows them to download the images they want from the galleries, which I can monitor and track and if I want to I can have them pay on-line for the images via Paypal. They can download low res images to use in lay-outs and request images that are not on view. So for me and a growing number of professional photographers around the world, web clients like this offer a complete, safe and efficient solution. It’s probably fair to say that it’s aimed at high-usage and won’t suit writers who only occasionally send image files – but my clients and editors seem to like it and find it very handy.

Conclusion

By spending some time thinking though an efficient and thorough digital workflow, your time and energy will be well spent and your images will always arrive in the best possible state for publication. You will have a well referenced and accessible photo library and your editors will know that you can be relied on to produce professional work  that doesn’t need loads of post production, captioning and key-wording at their end to be useable. The sooner you get organised the better!

Week 11 Influential photographers

This week we will be learning about:

• Influential contemporary and historic photographers
• Feedback on final photography for assignment 3
• Personal studio portraiture

 

This is Ansel Adams. Do you know who he is? Would it surprise you to know that he is probably the most influential and respected landscape photographer there’s ever been?

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He was in part responsible for the formation of the USA’s National Parks legislation. His black and white landscape prints are some of the highest quality photographic prints ever made. As photographers, we ought to know something about a photographer this influential…

Your task:

The BTEC Unit that we are studying is  “Unit 5, Creative Camera Technique”.

The first grading criteria (see grading criteria on all assignments) states:

To achieve this unit a learner must:

1. Know about the work of past and contemporary photographers

To fulfill this part of the grading criteria, you must undertake some research into at least one contemporary and one historic photographer who is recognized as important in the visual arts and has had a lasting influence.

1. Write a brief biography outlining the life and work of your chosen photographer/s. 250 words will be sufficient.
2. Include examples of their work (at least 2 photographs).Provide a caption and an explanation of why it is representative of this photographers work.
3. Try to compare the work and impact of your chosen photographer/s with their own contemporaries and say why you think they achieved recognition. In other words, what were/are they doing that’s different from other photographers around them.
4. Explain why you have chosen this particular photographer and express your opinion about their work.
5. Include at least one historic and one contemporary photographer

A list of both historic (dead) and contemporary (living) photographers will be provided but you can choose your own photographers if you wish. Ensure that they are well known and influential.

Why do I need to know about historic photographers?

The answer lies in having an understanding of how photography has shaped and continues to shape the world we live in and how we perceive it. Here’s a link to list of famous and influential photographers who have played their part in forming our view of the world. Have a look through the images and you will begin to understand the impact that the still, photographic image can have on us. As photographers, we all have the latent opportunity to use our photography to impart meaning and understanding of the world around us.

I sometimes make the point to students that it would be very strange to want to be a musician but not listen to music! The same goes for the visual arts like photography. Having an appreciation, understanding and knowledge of past and contemporary photographers and photography will help you to understand and place your own photography and ideas in context and show you what is possible.

Here’s a list of famous photographers, past and present complied by TripWire Magazine:

http://www.tripwiremagazine.com/2011/10/famous-photographers.html

Here’s another list, this time Professional Photographer magazines 100 most influential photographers of all time…

http://www.professionalphotographer.co.uk/magazine/photographic-inspiration/100-most-influential-photographers-of-all-time

Contemporary photographers that I like

Here’s some photographers that I recommend to you, from my own personal favorites:

Landscape

Charlie Waite: http://www.charliewaite.com/

Joe Cornish: http://www.joecornishgallery.co.uk/

David Ward: http://www.into-the-light.com/

Wildlife & Nature

Art Wolfe: http://www.artwolfe.com/

Jim Brandenburg: http://www.jimbrandenburg.com

Frans Lanting: http://www.lanting.com/

Sport & Action

Bob Martin: http://www.bobmartin.com/

Dave Black: http://www.daveblackphotography.com/

Jimmy Chin: http://www.jimmychin.com/

Photo-jounalism

Steve McCurry: http://www.stevemccurry.com/

Martin Parr: http://www.martinparr.com/index1.html

David Alan Harvey: http://www.davidalanharvey.com/

Portrait/Fashion

Annie Leibovitz: http://www.brooklynmuseum.org/exhibitions/annie_leibovitz/

Jane Bown: http://en.wikipedia.org/wiki/Jane_Bown

Mario Testino: http://www.mariotestino.com/

Others…

Galen Rowell:

David Doubilet:

Yves Arthus Bertrand:

Jack Dykinga:

Michael Fatali:

Michael Yamashita:

 

Week 10 Studio flash

Studio Portrait Photography and Studio Health & Safety Notes

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Health & Safety in the studio:

1. Studio stands and background stands should be set up to be stable, tight and appropriately position to avoid becoming trip or fall hazards.

2. Lights should secured to studio stands appropriately and securely so that they cannot fall off, with clamps tightened.

3. Lighting cables represent trip hazards and should be positioned away from  areas where they would become trip/fall hazards

4. Electrical cables should be checked for safety and only used if in good condition. They represent an electrical shock hazard if handled or used inappropriately.

5. Lights can become hot after prolonged use and represent a burn hazard.

6. Working in the studio is often in low light conditions and can make moving around dangerous if there are obstacles or obstructions left on the floor. Keep working areas clean and tidy and free of any un-neccessay obstacles that may represent slip, trip or fall hazards.

7. Warn other people/models before using flash in the studio, some people will be light sensitive and flash photography can trigger epilepsy or similar reactions.

Video Introduction:

https://youtu.be/PPTEdmbhYok

You can shoot portraits with daylight (natural light), speedlights (camera flash) or studio lights (studio flash). They all have pros and cons and they all have their own light quality and “look”. You can mix flash with natural light and you can shoot in a studio, at home, in any interior space or outside on location. It’s up to you.

Let’s start with a studio portrait session and see how we adapt the techniques we use there to other locations and other light sources.

The studio set up

A typical studio will have a roll of back ground paper to keep the backgrounds plain, clean and simple, and some flashes on studio light stands with some flash modifiers. These can be shoot-through umbrellas, reflecting (bounce) umbrellas, soft boxes, reflector dishes or other stuff that’s more specific, like honeycombs, barn doors and other Gobo’s (means “goes between”). Most photographers choose umbrellas and soft boxes.

The idea of a flash modifier is to change the quality of the flash light. Generally, with portraiture we want to make the light soft and try to avoid shadows. Small light sources like flash guns produce hard light. Hard light causes shadows. To get rid of shadows, we need to change to the small, directional light into a big, diffused light. That’s what soft boxes and umbrellas do.

 

Quality of light

If we think about that outside on location, a bright sun in the sky is a small directional light and it produces shadows. Look at the pavement – see your shadow? Harsh isn’t it? But on a cloudy, overcast day, a big diffuser has been placed over the sun – the cloud cover. Now you don’t have any shadow do you? The light is soft and diffused. Just like in the studio with a soft box. Except that outside it’s more difficult to control and it has no direction, it’s all around you. So studio’s offer a more controlled environment in which to work.

OK, so we are going to use studio flash and a soft box to avoid shadows.

Setting the lights up

Where are we going to place the flash and the soft box? Let’s start by just putting it to one side of the sitter.

Side-lighting is pretty dramatic isn’t it? You get one side of the face lit and the other in complete shadow. It’s not a look that going to suit many people but it is very theatrical. The real problem is that we only see one eye and we really would prefer to see both eyes – they are very important in a portrait, they are what we are naturally drawn to and it’s where we look first.

So we need to change the lighting a bit. If we take the lighting around the sitter so it’s at about 45 degrees we can wash some light across the face and start to light the shadows as well.

Key Light:

When we use a single light source, this is called Key light. The key light is the main source of illumination and we need to recognize what and where the key light is when we are photographing. This is true of studio and location photography.

OK, that’s better, now we can see both eyes. The lighting still pretty dramatic but by raising the key light up a little and bringing it around to 45 degrees, the light is able to wash across the face, pass over the bridge of the nose and light up a little triangle of light on the sitters cheek. At the same time, it’s casting a shadow of the nose that falls down to meet the jaw line. Can you see that? That’s we are looking for with a single 45 degree light; a triangle of light on the opposite cheek and a nose shadow. This is the classic starting point for portrait lighting.

If you can do this, you can light portraits pretty much anywhere. It works for studio lights, speedlights, even natural light outdoors, but where it’s particularly effective is with natural light portraits shot using window light. You just have to look at the direction the light is coming from and place your sitter so that falls across their face at 45 degrees, to light up that little triangle on the cheek and cast a nose shadow – the softer, the better.

Point to note: OK, inevitably someone is going think that this is the only way to light portraits – and it absolutely is not! There’s any number of other lighting set-ups and portrait photographers all have their favourite way of doing things – their favourite look or style, some of which use lighting in a completely different way. But this a good starting point and it teaches you to take a good look at the what the lighting and shadows are doing.

What’s next?

We’ve got the lighting in about the right place, so now what? Well, not everyone want’s dark moody portraits. Sometimes we want to lighten things up a bit and fill in those shadows. We can do that with either a second “fill” flash or a reflector of some kind. You can buy reflectors easily these days, here’s the sort of thing that I mean:

They reflect the source light back up into the sitters face and soften and lighten the shadows. simple and effective. But actually any reflective surface will do. Different surfaces reflect light in different ways and produce a different quality of light. A matt white board will produce a soft light, a mirror will produce a hard light.

In this shot the shadows on the left have been filled in using a second studio flash with a soft box pointed slightly behind the sitter to also light up the background a little.

Notice that the light is still directional – the right side of the face is brighter than the left. This is important. It adds modeling, direction, depth and a sense of “three-dimensionality” to the portrait. This is done by balancing the lighting ratio between the lights. Using a reflector will already achieve this but if you add a fill flash there is a danger that it could be as powerful as the main light and swamp it! So we need to understand a little about lighting ratios.

Lighting ratios

Traditionally we try to keep the ratio between the key light and the fill light at around 2:1 or higher (3:1 or 4:1). This means that the Key light is brighter than the fill light by a factor of 2,3 or 4. Some photographers go as high as 8:1 for a dramatic look.

To translate that into stops of exposure, just divide the big number by 2. So…

2:1 ratio means the key light is 1 stop brighter than the fill light (2 divided by 2 = 1)

3:2 ratio means the key light is 1.5 stops brighter than the fill light (3 divided by 2 =1.5

4:1 ratio means the key light is 2 stops brighter than the fill light (4 divided by 2 = 2)

8:1 ratio is 4 stops difference and that’s almost as dark as using a single key light.

How about using reflectors instead of fill lights?

Good idea. Reflectors can be made of any shiny, reflective material and they work by reflecting the key light back into the shadows. Because you are using reflected light, the lighting ratio will naturally be something in the order of 3:1 already and reflectors can often give a softer and more appealing light than fill lights. Photographers use them all the time. And not just in the studio but out on location too, reflecting the sunlight back into the shadows on photo-shoots with models, or with still life subjects like plants and flowers.

Background lights and special effects

If you have access to more lights you can really go to town on producing some special looks for your portrait. Let’s have a look at a few examples.

Background light. Simple concept – light up the background with different light shapes and colours to create some background interest and frame your portrait with light.

Hair light. Another effective trick – hide the flash behind the model and shine through the hair…

Shadows. This is a great idea for creative portraits. Use shadows to create an impression. It needs a few props to make it work – most photographers use a light shone through a blind to create the stripy effect. Here’s a link to a great feature all about creating shadows on portraits.

http://www.whatdigitalcamera.com/techniques/camera-skills/people-and-portraits/301790/the-great-indoors-light-painting.html

How about setting up a home studio?

Why not? All you need is a roll of background paper (white and/or black), a couple of stands and a pole to support the background on, a couple of cheap flash guns that work on manual settings and some flash modifiers like umbrellas. Sync the whole thing together with some cheap wireless transceivers off ebay and you are ready to shoot.

Week 9 Flash basics

This week we will be learning about:

https://youtu.be/TWVnC9ZUgQE

Video introducing on-camera pop-up flash

• Flash guns and how to use them
• Feedback on research and planning for assignment 3

Modern film and digital camera’s use three basic ways of measuring and controlling flash exposure so let’s have a look at them in turn.

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Flash exposure control:

The first thing to remember about flash is that flash exposure is controlled by ISO and aperture in the camera, not shutter speed. The only affect that shutter speed has is on the ambient (natural or continuous light) exposure and of course with flash sync. Why is this?

Because flash duration is so short that shutter speed makes no real difference to how much of the flash light is captured by the camera. Flash duration is normally between 1/1000 and 1/30,000 of a second, depending on flash power and your camera can’t sync at those speeds (unless you have a high speed flash mode but that works a bit differently anyway), so at normal sync speeds of up to 1/250 second the flash is over before the shutter has even closed, hence shutter speed can’t control flash exposure.

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1: Manual flash mode

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Most modern flash guns have a manual mode and as we shall see later on, when using flash off-camera, this can be a very useful feature. In manual mode, the flashgun is operating totally independent of the camera, just like a studio flash. The amount of flash light put out by the flash unit is controlled by the photographer selecting a power setting, which typically will vary from full power (1/1) to 1/2, 1/4, 1/8 and so on right down to maybe 1/64th power or less depending on the flash design. The only way of gauging the correct output for the flash is by testing the exposure.

Set an appropriate/”guestimate” power setting on the flash and an aperture/ISO combination on the camera and test it. Shutter speed will be whatever works best for any ambient light there is. If it’s too light, reduce power or decrease aperture (or ISO or both) if it’s too dark increase power or open the aperture and/or increase ISO.

Or if you are shooting film, use a flash meter or calculate flash distance and power using guide numbers – but honestly does anyone do this these days?

Of course, if you change any of the camera settings, or move the flash to a different flash-subject distance, the flash power will need to be altered to a new setting, so it’s not a suitable mode for fast changing or moving situations.

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2: Auto flash mode

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The Auto mode is designed to be more flexible and give us a degree of automatic flash exposure in changing situations. The flash is not directly controlled by the camera but rather it has a built-in light sensor on the front panel that can detect flash reflected by the subject. The sensor cuts the flash power when enough flash has lit the subject for a good exposure.

In order to do this accurately, the flash needs two bits of information from the photographer. It needs to know the ISO you are using, since high ISO’s need less exposure and it needs to know the aperture (f-stop) you have set. With this information the flash sensor can control the flash output appropriate for the reflective properties of the subject.

A dark subject (which reflects less light) can be given more flash and a light subject (which reflects more light) gets less flash. The system can be customised easily too – if you dial in f5.6 on the flash but use f8 on the camera, the flash will give 1 stop less power than you really need so you will have fill-in flash. If you dial in f8 on the flash but use f5.6 on the camera the opposite will happen, the flash will give you 1 stop more power than you need – over-exposure.

Is the system fool-proof? No. Since the correct flash exposure is dependent on the flash sensor correctly “seeing” the flash reflected from the subject, if the subject moves, you can get an unknown reflective quantity; if you change the camera settings but forget to update the flash settings your flash exposures will be wrong and if you shoot subjects with unusual or variable reflective properties the results can be unpredictable.

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3: TTL flash mode (iTTL/ eTTL/pTTL and so on)

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The third and most dependable flash exposure system is TTL or Through The Lens. In this system the flash exposure is measured off the actual camera sensor or film plane by an internal flash sensor built into the camera body. Since the flash sensor is measuring the flash actually falling on the sensor or film, the system is very accurate and takes account of all the variables including lens absorption, filters and so on. All the camera has to do is tell the flash when to start and when to stop.

The flash is easy to adjust too. There is normally a plus/minus +/- button or control for flash exposure compensation on the back of the flash and also on the camera. Dedicated flash guns connected to the camera can be controlled using either the flash +/- control for more or less power, or the camera mounted +/-, or in fact a combination of the two if you like!

However, in order to work, the flash has to be “dedicated” to the camera – in other words built to work directly with camera it’s being used with – and the camera has to be able to communicate with the flashgun. Nikon, Canon, Sony, Pentax, Olympus and others all have their own dedicated TTL systems with features and functions, and cute names like iTTL (Nikon) and eTTL (Canon)

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Using the flash off-camera

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Because the camera and flash are dedicated together and linked via the hotshoe contacts, all the exposure information of f-stop and ISO can be passed directly to the flash. This is no problem when the flash is hotshoe mounted but presents problems with off-camera use. If the flash is tethered to the camera using a dedicated cable, the information can be transmitted easily but if the flash is going to be used remotely off-camera, some other way of communicating must be used.

Nikon and Canon both use an encoded visible-light pre-flash system using a master “sender” flash (often the pop-up flash) and slave receiver flashes. These systems work well in low ambient light or in the studio but can be unreliable in bright ambient light where the flash signals can be overwhelmed by the existing light.

The slave flash’s light sensor, which is mounted on either the side of the camera (above) or the front plate (Canon) also needs to be pointed ‘line-of-sight” towards the sender flash, mounted on the camera which is inconvenient in some situations.

This is where “wireless triggers” come in which we will look at in a separate article.

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Built in pop-up flash

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So, now that we have reviewed the basics of flash exposure, let’s have a closer look at the little pop-up flash gun built into your camera.

Most pop-up flash guns are triggered automatically by the camera in Auto mode but must be turned on in P (program) mode and all other modes.  In Auto mode, the camera will turn on the flash whenever the meter senses that the ambient light level is too low to achieve a reasonable shutter speed that you can hand-hold without getting camera shake.

Dedicated flash

Because the flash is built-in, it is fully dedicated. In other words, the camera can controll it’s output by metering exactly how much flash is required and it can control all the functions via the camera controls.

Once the flash is on, you can select what kind of flash mode you want to use via the flash mode button. There’s a number of options so we should go through them and explain each one:

Flash Modes on the camera

We can usually choose between different flash modes on the camera, depending on the circumstances and the kind of flash we need. Different cameras have their own individual flash modes according to the camera makers design and many modern DSLR’s have integrated many of the flash modes into the auto settings anyway, so you don’t need to set them yourself.

Auto flash

Auto flash just does everything automatically for you but there’s a couple of things worth noting.

First of all, if you use auto ISO, the camera will set the lowest default ISO setting (usually 200 ISO) and keep it there. This will often mean your backgrounds will go black because the camera is not exposing for the ambient light, only the flash light. So turn your ISO to manual and push it up if you want to expose for the ambient light as well.

And second, you don’t have to just accept whatever flash exposure the camera puts out. You have a flash exposure compensation dial on the camera (FEC). This allows you to over-ride whatever flash power the camera is setting and dial in either minus (less) power or plus (more) power, according to your needs.

Red eye reduction

This will help you reduce the effect of “red eye’ in portraits taken with the pop-up flash. The flash fires a series of rapid pre-flashes to force the portraits pupils to constrict (because you just blinded them with a strobe!). This means less flash penetrates the eye and you reduce red-eye. Often you you can combine red-eye reduction with other modes like slow sync or rear/2nd curtain mode. Hint – only turn it on when you really need it! Red eye reduction is usually found in the flash menu.

Slow speed sync.

On some cameras (Nikon’s in particular) you are able to set a flash mode called Slow Speed sync. In this mode, the camera is able to use a slow shutter speed to record the ambient light along with the flash to light the main subject. Canon cameras often incorporate this into the normal auto mode so you don’t have to set yourself – see your camera manual for help.

On my Nikon d5100, when I pop up the flash and go through the various shooting modes, this is what I get…

Auto flash in:

Manual – I can set any shutter speed/aperture combo I like up to 1/200th which is the camera sync speed.

Aperture priority – the camera will use any shutter speed up to 1/200th. I can set any aperture I like.

Shutter priority – I can set any shutter I like up to 1/200th which is the sync speed The aperture will be set by the camera according to the ambient light level.

P Mode – The shutter will default to speeds between 1/60th and 1/200th which will often result in a black background.

Auto – The same thing, I get speeds between 1/60th and 1/200th with black backgrounds in low light levels.

So, I can only expose for the ambient light, ie the background, when using my pop-up flash if I use the manual, shutter or aperture priority modes. In all other modes, my shutter speed is restricted to speeds that will render the subject fine with the flash but the background as either underexposed or black. This is not good. However, the Slow Speed Sync flash mode over-rides this and allows you have much slower shutter speeds in these shooting modes so you get to expose for the background ambient light as well.

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Using a pop-up flash

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Fig 1. Program mode/Auto flash – I get good flash exposure but a black background,yuk!

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Fig 2. Program mode/Slow speed sync flash mode – that’s better, now I get some ambient light and create a nice atmosphere, I can see the background. However, there’s a problem you have to watch out for. The shutter speed needed to be around 1.5 seconds to record the dim background lighting, so that means using a tripod, otherwise I’m going to get camera shake.

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Fig 3: If I don’t use a tripod with slow speed sync, I record all the movement of holding the camera…

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Slow speed sync for effect

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Slow speed sync with camera shake – or motion blur isn’t always a bad thing. In fact, photographers use it all the time…

Photographers use slow speed sync to inject motion, ambience and atmosphere into their flash pictures to bring them alive. The slow shutter speed creates motion and blur whilst the flash, being bright and fast, creates a sharp image over the top. Try it with party pictures, you will be amazed how effective it is. Different shutter speeds create different amounts of motion blur and will control how light or dark your backgrounds appear.

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Rear/2nd curtain sync

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The last flash mode we’re going to talk about is rear curtain or 2nd curtain sync. The idea is that we can choose to fire the flash at either the start of the exposure (the conventional way) or at the end of the exposure (rear/2nd curtain method). What’s the difference between the two? Well, if the flash fires first, and then the ambient exposure continues, any motion blur (as we see above) will appear in front of the sharp subject. That can look odd. We don’t really expect to see “ghost” images projecting in front of the subject, but don’t mind seeing the blur behind the subject. That looks more natural. Here’s an example…

See how all the action (the light trails in this case) appear first and then the runner, caught sharply with the flash is at the end of the exposure. So Rear curtain or second curtain flash creates images that use slow speed sync in a more realistic way. i use it all the time. In fact my cameras are set to slow speed rear curtain sync as the default setting.

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Flash Exposure Compensation

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Let’s just remind you about flash exposure compensation again, it’s very important.

Being able to set more or less (+/-) flash power means that you can give your pictures just a little pop of flash to brighten up or fill in those shadow areas any time you like. Try shooting a portrait with different amounts of minus flash exposure compensation, starting at -0.3 and going on up to -3 (stops). At -3 stops you shouldn’t see any flash at all!

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Daylight Balanced Fill-in Flash on Location

The second part of the assignment deals with using flash as part of your daylight photography, where you can mix ambient (natural or continuous lighting) with flash from your camera. Nearly all modern DSLR and Bridge style cameras have a built in flash, until you get to the “Pro” models, which assume you will be using a more powerful and flexible speedlight on the cameras hotshoe.

The little pop-up flash is more useful (and more powerful) than you many people think and we’re going to take a look at how to get the best out of it and in what situations it can be applied.

What is ambient light?

Before we go much further, it would be a good idea to remind ourselves of the difference between ambient light and flash light. Ambient is continuous light. It’s the light that fills the room or the outdoors; it’s normally daylight, sunlight, but it can also be room lights like tungsten or fluorescent, or even moonlight. The defining characteristic is that it’s continuous and that means that the camera can record it using an appropriate shutter speed.

Here’s some examples of ambient light:

This is a domestic scene shot under ambient tungsten household lighting. As you would expect, the camera has recorded the very warm “yellow/orange” white balance but otherwise the shot looks fine, with good detail and reasonably even lighting across the subject.

Here’s another subject, this time shot under ambient daylight. the colours and white balance are natural and the shot has good detail and lighting across the whole subject.

Why would we use flash in ambient light?

Good question. The next shot the ambient light has caused some problems. The portrait of the white flowers was shot against a window with ambient daylight. The daylight behind the subject is clearly brighter than the light on the front of the flower heads, so we get dark shadow areas, loss of details and a semi-silhouetted look.

Now, if we add some fill-flash to the scene using the little pop-up flash, we can pump a bit of light into the front and get the balance just right. In fact, adding flash does more than just light up the dark areas.

Flash adds sharpness and colour

Flash is a very rapid burst of light, it catches the subject and freezes any motion that might be there, so it helps to add sharpness to the image. It also adds colour, because it penetrates any “shine” on surfaces such as you get on waxy leaves and it saturates colours in clothing and other surfaces.

Danger! Reflection…

You do have to watch out for “flash reflection” though – if you have any reflective surface directly in front of the flash lens, the camera will record a harsh reflection of the flash, which is unsightly and distracting.

Avoid this by shooting from an angle, so the flash bounces off the reflective surface away from the camera rather than directly back into the lens. I did this with the flower subject above. The window pane would have reflected the flash, but I shot from 45 degrees so the flash bounced away from the lens.

Be creative with fill flash

Here’s another example. In this shot, I used a powerful spotlight behind the subject to create a silhouette and then “filled it”  with some pop-up flash from the camera.

Use Flash Exposure Compensation

In the shot of the carved duck above, I used the flash exposure compensation controls to dial in -1.7 stops of flash. I wanted to fill-in the shadows but blast the the thing with light! I needed to keep the ambience of the backlighting so it was important not to overwhelm the shot with flash. The flash exposure compensation (FEC) control on your camera allows you to set either more (+) or less (-) flash output.

We rarely need to set more but we use minus flash compensation all the time, to control just how much flash lighting our subject gets. It’s no different to using the power controls on the studio flash to set how much flash a portrait subject gets and the real key to daylight-balanced fill-in flash is set just the right amount of fill-flash to compliment the existing ambient light, not overwhelm it.

Week 8 Differential focusing

One essential skill that we need to master is called differential focusing.

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It’s not really about using a specific camera control or setting, but rather it’s about how we use a combination of depth of field, composition and thinking about how the subject we are photographing will look to the viewer. So it’s more of a conceptual thing. Differential focusing is about isolating a single subject using a short depth of field and considering where you will place the emphasis, the focal point in your composition and how it will relate to all the other, out-of-focus elements in your composition.

Let’s have a look at some examples.

In the image above, I saw the sign post pointing out the National Cycle Network. On it’s own it doesn’t make much of a photo. But if I waited for a cyclist to ride past, in the background, it would make a more interesting shot. Showing an out-of-focus cyclist in the background would give the sign added meaning and context.

I needed to separate the subject (the sign) from the background (the cyclist) so I differentiated between them by using a short DOF to isolate the subject. A cyclist eventually turned up about 10 minutes later and I shot the photo. The background relates to the foreground and it gives us lots of meaning and information. But the subject remains the sign. This is differential focusing working well. Photographers use this idea all the time.

Here are some more examples:

Example 1: Sailing boat mooring at the dock.

The story that I wanted to tell here, was all about the activity on the landing stage, about the sailors tying up their boats and working with ropes and so on. The ropes and lines therefor were important and I wanted to make sure they stood out as the subject. The answer was to focus in on the ropes and the hands of the sailor, keeping them sharp and making them the focal point, differentiating between them and the boat in the background. The boat is the context, the ropes are the subject.  They relate to each other. Using a short depth of field to throw the background out of focus allows me to focus your attention on the subject, rather than the background.

Example 2: Wine glass on a table

In this shot, the subject is the glass of wine. It creates an atmosphere and an ambience for the photo of a restaurant table setting. The white napkins and table service are not, in themselves particularly interesting but the wine glass, with it’s rich colour and illusion to an appetizing meal to come, offers a perfect focal point. I am able to include the impression of  the rest of the table setting by including it all as a soft, out-of-focus back drop and foreground. Controlling the depth of field to just include the wine glass allows me to do this. This is differential focusing being used to create a story or an idea.

Example 3: Map and compass

In this shot, the story is all about navigation on the fells. The sharp focus on the hands, using a map and compass show us that these are the important subjects. I have separated them from the background by using a short depth of field to throw the background scenery out of focus. I have therefore differentiated between subject (map and compass) and context (background scenery). If I included the background scenery in sharp focus there is a danger that the story or the meaning of the photo would be lost. It might start to look more like a landscape photo!

Example 4: Computer keyboard

Remember, differential focusing isn’t just about controlling a short depth of field – it also allows us to make connections between subject and background. Sometimes the out-of-focus background gives us more information, more meaning and is therefore more important than the in-focus subject. In this shot, it’s only the out-of-focus background elements that allow us to infer that this shot is all about people using computers. It’s not just a still-life photo of a computer keyboard.

Controlling your depth of field:

If you need more information about depth of field (DOF) please read “Week 3 Apertures & Depth of Field” first.

Let’s look at what we need to consider in order to control where our depth of field, or zone of sharp focus falls.

Foreground

In this photo, the elements consist of a book, a drink and a glass. The aim of the shot is focus the viewers attention on foreground subject (book) but use the other elements (drink and glass) to provide some simple background context.

The book is placed close to the camera lens. This will immediately create a short DOF. Remember that DOF is relative to subject-to-camera distance. The shorter the distance, the shorter the DOF. The lens is set at 70mm, a short telephoto setting. Telephoto lenses shorten DOF because they have the effect of bringing the subject closer to the camera, another way of creating a short subject-to-camera distance.

We have created a situation now, where focusing on the book, close to the lens with a telephoto will guarantee that any DOF we get will remain very small. In fact it’s so small that we get away with shooting at f8. When we’re close up, we get a tiny DOF at any aperture setting.

So as long as the other elements of the photo are placed at a reasonable distance they are guaranteed to fall outside of the zone of sharpness, the DOF. OK, that was easy. Now let’s move to the middle distance…

Middle distance

In this photo, the subject is the drink in the middle. The foreground and background elements are just supporting subjects that give some simple context and added interest. The lens is set to 80mm in this shot. Being slightly more telephoto than in the first shot, the available DOF at any aperture will be decreased slightly and that will help us to keep foreground and background out of focus.

The book is placed very close to the camera to ensure that it remains outside of the DOF created around the bottle.

There’s another important point to consider here; Because DOF is relative to distance, when we focus on more distant objects we create a larger zone of sharpness and as a guide, 1/3rd of this zone will be in front of the subject and 2/3rds will be behind. So as we focus on objects that are further away from the camera it becomes more important to consider the background elements and keeping them outside of the zone.

To ensure that the glass in the background remains out of focus, we need to move it even further back. If it’s too close to the middle object – the bottle –  it might be included within the DOF around the bottle and we don’t want that to happen.

Background

In this photo, we are focusing on the background element of the shot. In the previous photo, the glass was in the background but it doesn’t make a very interesting or bold subject so in this shot the bottle has replaced it.

Focusing on the background brings some more problems because we are shooting over a greater distance. We know that subjects that are further away will have more DOF because of “subject-to-camera” distance. So the challenge is to include foreground elements but keep them out of the zone of sharpness. Fortunately, we also know that most DOF is created behind the subject we focus on, not in front of it.

So as long as we have enough distance between the sharp, background subject and the unsharp foreground we can create a decent differential between the two. If the objects are too close together, the foreground elements will start to appear too sharp and too dominant and we will loose the idea of differential focusing. The easiest way to ensure all the foreground elements stay out of focus is to place them close to the camera, or get up close to them.

Week 7

This week we will be learning about:

• Composition
• Feedback on final photography for Assignment 2

The composition lecture will be a Powerpoint presentation, with examples for us to to consider and discuss.

https://youtu.be/7ZVyNjKSr0M

Composition Video with Steve McCurry

Week 6 White balance

 

This week we will be learning about:

• White balance
• Auto focusing
• Feedback on initial test shots for assignment 2

https://youtu.be/LiPL73mLeJ8

Watch the YouTube video at this link

What is white balance and why is it important?

The white balance control on the camera is designed to calibrate the camera’s exposure system to capture images that display natural colours under different lighting conditions. Think of white balance as a way of making sure that a sheet of white paper actually looks white in your photo.

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What colour is daylight?

Daylight is actually a mix of three different light sources. Sunlight is essentially warm, yellow light but it’s not the only light we see. Skylight is the light that bounces off our atmosphere, our sky if you like. And light also bounces off objects and surfaces on the ground. If those surfaces have a strong colour they will affect the colour of the light they reflect, so we have reflected light as well.

So daylight is a mixture of sunlight, skylight and reflected light – which combine to alter the colour of daylight in a variety of ways.

Why is the sky blue?

In the middle of the day, with the sun high in the sky, daylight is quite blue. Some people think that the sky is blue because it’s reflecting all the sea on the planet. That’s not right, the sea is blue because it reflects the sky.

This is from http://www.sciencemadesimple.com/sky_blue.html

“The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air. However, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue”. 

Since so much of the daylight we see includes skylight, our sheet of paper is being lit essentially by “blue Light”. And although we see what we refer to as “natural colour” under a variety of different light sources, and we see a sheet of white paper under different colours of light, we always seem to see it as “white“.

Of course we’ve evolved with a visual system that is specifically designed to deal with seeing the world in this way and it’s very good at it. Our visual system “filters” out colour casts and always tries to present the world to us with”natural colours”, where white always looks white, whatever the light colour. But a camera can’t do this.

The Kelvin scale

The Kelvin scale is used to describe colour temperature. Orange light, such as you might get from a candle, has a low Kelvin temperature – about 2000K; yellow light from incandescent, tungsten, household bulbs is about 3000K. As the light colour becomes increasingly blue and then white, the colour temperature goes up. It can go as high as 11000K for white light. Seems odd, that blue should be a higher colour temperature than orange but remember, a blue flame is much hotter than an orange one and we describe extreme temperatures as “white hot”. Normal daylight, under a bright sun at midday is about 5500K – quite blue.

White balance in photography

In order for the camera (or a RAW converter) to process colour information, it has to know what colour the light source is (or should be). This is what the white balance control does. If you shoot under daylight white balance conditions the camera will render colours as naturally as possible using a starting point of around 5500K (kelvin) as the light source.

What happens if the light source is not daylight? What if the light source is tungsten bulbs, or florescent tubes or sodium flood lights? If the camera is only calibrated to produce accurate colours at 5500k it will get colours hopelessly wrong under these different coloured lighting conditions.

The white balance control allows you to calibrate the camera for all kinds of different lighting conditions. Typically, a digital SLR camera will offer you a range of adjustments.

The photo above shows how a daylight white balance (5500k), used under typical daylight conditions, renders colors that look quite natural. However, if we use a Tungsten white balance under the same conditions, the image shows a strong blue colour cast.

This is because Tungsten or Incandescent lights, like household light bulbs, produce a strong orange/yellow colour light. Tungsten white balance adds blue to counter-act the orange and render colours in a more natural way. If you use Tungsten white balance on a daylight scene, the camera will still add the blue and the result will be scenes that show a strong blue colour cast as seen below.

Similarly, if we use a high Kelvin value, like 10,000k, we are adding lots of yellow to the scene. This is intended to warm up scenes that have a very strong blue colour cast, like deep shadow areas. Again if we use a high K point under normal daylight conditions (which would normally be around 5500k) the camera adds yellow and the scene looks like the image below.

Examples:

In the following examples, I took a daylight shot of this Scottish castle in winter sunlight which was quite cold, particularly against the blue sky. I then processed the RAW file in Lightroom several times, just changing the white balance to the pre-sets available in the Lightroom panel. Notice the differences?

1. WB: As Shot – the scene looks quite cold and stark.

2. WB: Daylight. The stonework looks much warmer now, although the blue sky has lost a little of it’s rich blue colour.

3. WB: Cloudy. Now the stone is a much warmer tone and the blue has faded a little more.

4. WB: Shade. Again, as the image is “warmed” the blue sky moves towards yellow.

5. WB: Tungsten (incandescent). Tungsten white balance adds blue to the image to get rid of the orange colour that is generated by incandescent (household) bulbs to retain the natural colour balance. But if you add tungsten white balance to an image that is already balanced for daylight it will push the colours towards blue.

6. WB: Fluorescent. Adding fluorescent white balance is intended to re-balance the colour cast caused by fluorescent lights which is normally green or purplish. If you add fluorescent white balance to a daylight picture like this castle, you can see the faint purple/pink hue in the stonework.

7. WB: Flash. Flash white balance is pre-set at 5500K, the normal K point for daylight. The idea is that this will produce natural colours under flash light which is balanced to emulate daylight. So if you use this pre-set on images with no flash present it just sets the same K point as the daylight WB setting.

8. WB: Auto. On the camera, the auto setting is essentially the camera’s best guess at the optimal white balance for the scene and is calculated in the camera using algorithms programmed by the software designers. I cannot find a simple or definitive explanation of exactly how they do it but it has something to with calculating the red green and blue values of the image and adding them together to produce grey, then subtracting the “over-spill”! Because I shoot RAW files I can change or tweak the white balance at any time during image processing so I normally shoot Auto WB and assume that it will get me close. If I shoot Jpeg I tend to set the WB manually. These images where all tweaked in Lightroom so the AWB in-camera setting is actually the 1. As Shot image at the top and it’s a bit too cold for my liking. Lightrooms own Auto-white balance setting, shown below seems to repair this quite well.

If you recognise the kind of lighting you are shooting under you can dial in the appropriate white balance setting, allowing the camera to filter out colour casts and warm up or cool down the photos ambient colour balance.

We don’t always want a neutral white balance. It may be empirically “correct”, but often we prefer our photos to have a certain look, often a little warmer, particularly for landscape and portrait subjects.

Here’s a landscape subject. The white balance for this subject is “correct”. The grey tones are neutral and the image looks cold because it’s a cold, grey day.

Here’s the same shot with the white balance adjusted to warm up the look of the photo. I set the white balance to cloudy to get a warmer look.

Which one do you prefer? I think most people would choose the second, warmer version. It’s not “correct” but it looks better.

White balance with jpeg and RAW.

One important consideration with respect to white balance is whether you are shooting in jpeg or RAW file format. RAW shooters have a big advantage because RAW files are not processed by the camera but on the computer after downloading, using RAW converter software like Adobe Lightroom, Adobe Camera RAW (ACR) or Apple Aperture or even the RAW software that came with your camera. Because the RAW files are unprocessed, no colour attributes have yet been fixed to the files. You can set the white balance – which is after all just a baseline calibration – at any point you like and change it at will using the RAW processing software. But a jpeg file has to be processed in the camera before it can be compressed and saved to the camera’s memory card.

So with a jpeg, ideally the white balance should be fixed at the point when you shoot the picture. You should try to assess the white balance result when you are shooting and make appropriate changes if the Auto white balance isn’t getting it right. It is perfectly possible to change the white balance of a jpeg file after it has been downloaded but it can be problematic. Generally speaking it’s difficult to re-process jpegs as accurately as you can with RAW files and trying to do so can lead to image artifacts and a degraded file. You have to remember that with a jpeg, you are working with a pre-processed file that only contains 256 levels of tone (an 8 bit file) and any additional tonal information that might have been contained in the original RAW data has been deleted when the camera compressed and saved the jpeg.

In short, a jpeg file is designed to be used right out of the camera and is not meant to be messed with or re-processed on the computer. You can do it, many people do, but it often leads to worse quality image file rather than better.

WB in the studio with Raw

Finally, there is the problem of setting a white balance in the studio for use with studio flash lighting. The lighting from flash will be a constant white balance so it makes sense to fix the white balance in the camera even when shooting Raw so that in post production you have pretty accurate base line WB to start from. Using the Flash white balance pre-set or a specific k value would be the solution.

https://youtu.be/LiPL73mLeJ8

White balance video

Autofocus explained!

Single Servo Vs Continuous Servo:

The single servo options means that the camera will lock onto a subject, using whichever focus point options you have selected, but won’t allow you to shoot a frame until it has confirmed focus. This is safe but can be slow and you may loose a shot whilst the camera is hunting for focus.

The continuous servo option allows you to shoot a frame or multiple frames (continuous shooting) even if the AF hasn’t actually confirmed focus. This is fast but you may loose frames because they are not focused.

Auto Servo/AI Servo and Manual focus options:

Nikon has an option called Auto-servo and Canon has AI Focus AF, which are both intelligent options which switch automatically between single and continuous servo modes when they detect movement  in the subject.

Manual focusing is best switched on/off on the lens rather than in the camera menu and is helpful when AF modes are either unreliable or not required.

Single point Vs Multi Point focusing

Single point focusing uses just a single, selectable focus point, using the four way button the back of the camera. You can place the focus sensor where you want it.

Photo: http://photographylife.com/dslr-autofocus-modes-explained

Multi point, 3D tracking and Dynamic Area are all focus modes that use several focus points around the frame to determine subject and try to track movement. Some new DSLR’s even have a face detection focus mode and a closest subject mode. A good overview of all these options are at the link http://photographylife.com/dslr-autofocus-modes-explained

Photo: http://photographylife.com/dslr-autofocus-modes-explained

Focus assist lights:

Some DSLR’s incorporate a focus assist lamp on the front of the camera body to help you to focus in low light or at night. It’s worth having this option enabled most of the time (unless you want to be unobtrusive).

Focus stacking:

This is a technique used in macro photography and other applications where focusing can be critical but difficult. It involves making several exposures with different focus points from a tripod mounted camera and combining all the images together in software in post production. There is free software available to help do this and lots of articles and videos on-line to show you how.

Hyperfocal or Zone focusing

Hyperfocal distance, sometimes called Zone focusing, as you will remember from our Depth of Field and Aperture discussions, involves pre-focusing to a given distance and using a given small aperture (often f8 to f22) to achieve a zone of sharp focus from a known distance in front of you to a far distance, often infinity.

There is a good article that covers this technique at http://digital-photography-school.com/ultimate-guide-to-zone-focusing-for-candid-street-photography

A good resource for a detailed analysis of all of the above:

http://photographylife.com/dslr-autofocus-modes-explained

Focusing modes and options on-line feature:

http://www.digitalcameraworld.com/2012/10/01/best-camera-focus-techniques-10-surefire-ways-to-get-sharp-photos/1/

 

week 6white balancecontrolexposurecolour

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Week 5 Exposure & Histograms

• All about exposure and histograms…

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It’s possible that you have used a camera for a long time, exploiting the auto programs and modes without really grasping any of the principles of exposure, metering or interpreting histograms.

Metering Modes

http://youtu.be/B1H3WYkODWA

Metering modes

Your camera is equipped with several ways of metering for exposure. It has, generally speaking, three metering methods or patterns, that can be chosen by the photographer; The first is called Evaluative or Matrix metering, then we have Centre-Weighted orPartial and finally we have Spot metering.

Most of time, Evaluative metering takes care of all our needs. It’s sophisticated, accurate and very flexible. Many photographers rarely, if ever use anything else. It takes exposure information from every part of the frame area and considers which focus points are active to work out where the subject is. The system can allocate importance to various areas of the frame based on this information and some even compare known parameters and lighting situations built into the cameras on-board data-base before coming up with a best-guess at the optimum exposure for your situation.

However, there are occasions when evaluative metering gets it wrong – then it’s time to switch to another method. Centre weighted and partial metering systems give emphasis to the centre of the frame with decreasing sensitivity to the outer edges. This assumes that the subject will occupy the centre of the frame and that it can safely ignore the outside, background areas. Perfect for portraiture in fact.

And finally we have spot metering where the camera only takes exposure information from a small, narrow (typically 3 or 4 degrees) angle of view in the very centre of the frame. To use this, the photographer must think of the spot area as a “target” and aim it at the important part or parts of the frame that need to be metered accurately, then use this information to figure out correct exposure.

Manual Exposure Mode

In MANUAL mode, (the “M” symbol) we can use the camera’s built in TTL (through the lens) light meter to gauge our exposures, by aligning the cursor with the “correct exposure” marker on the light meter.

image

Because we are using the camera in Manual mode we can set the exposure just as we like. We can over or under expose for the subject by as little or as much as we feel is necessary (a third of a stop at a time) and we can review the result on the camera monitor to see if we like the result. Clearly there is no need to use exposure compensation in Manual mode, (you are not having to “compensate” for the camera making any auto exposures) so this control is not normally available to you in this mode.

If you have never used Manual mode before, you might appreciate a bit of guidance; First of all try to decide what your “priority” is. If you are shooting sports, often the priority is using a fast shutter speed to stop the action – so you would set your chosen shutter speed and then use the meter to find the appropriate aperture to give you a good exposure. If your priority is depth of field, either short (portrait) or long (landscape), you would set the aperture of your choice and use the meter to find an appropriate shutter speed. If you are hand-holding the camera, one of your priorities will always be to eliminate “camera shake” by ensuring you are setting a fast enough shutter speed, but as always, the exact combination of shutter speed and aperture that you decide to use in the end will be your decision based on your particular creative intentions and priorities. In simple terms, using the manual mode is a case of setting one of the parameters and using the meter to determine the other.

Exposure Compensation

http://youtu.be/-SjTTQ0UTyI Exposure compensation

First of all, we should remind ourselves about the use and function of the exposure compensation controls. Normally indicated with a plus/minus symbol, the exposure compensation button or dial allows the photographer to shoot in a priority or program mode, whereby the camera does at least some of the exposure control. It doesn’t take long before the photographer realises that the camera’s built in exposure metering system is pretty good most of the time but not infallible. In fact there are plenty of situations where the camera is easily “fooled” by tricky or extreme lighting situations. Try shooting a portrait with the sun right behind the models head and you’ll find out quick enough.

Here’s a shot of a walker, in bad weather (rain), in bad light (under trees) and with bright sky behind – enough to confuse any camera meter. The camera tries to find an exposure that will balance the extreme tonal range from highlight to shadow but it doesn’t know that the “walker” is the subject so it can’t prioritize it.  The result is that overall, although the exposure is a good balance that includes most of the tonal range, the subject (walker) is too dark.

What can we do about this? We can use the exposure compensation button, adding some “plus” compensation to slightly over-expose the cameras settings and render the walker with more detail.

Of course, as we give the shot more exposure and “lighten” it up we force the brighter areas of the shot to over-expose by quite a bit. There’s no way around this, at least not without using a flash. Introducing flash into the exposure is a good way to compensate for extreme differences in exposure values in a composition because then we can expose for the highlights and just light up the dark areas with our flash…

So the exposure compensation tools that we have on our cameras will allow us to overcome situations where the camera meter is “fooled’ and allow us to “tweak’ the exposure either brighter or darker to get what we feel is an optimum exposure for our subject – usually at the expense of some other, background or foreground area of the frame.

Histograms

https://youtu.be/hNj-KRUztLY

Histogram Video

Understanding histograms is a key part of judging exposure in digital photography. It could be argued that histograms are not necessary when you can just look at the photo on the back of the camera but this ignores problems with viewing the camera monitor under bright lighting, accurately assessing highlight and shadow clipping and understanding tonal range.

First we should describe what the histogram function is and how to interpret it. The histogram is a simple bar chart – nothing more. It consists of 256 bars. The bars start at the left end of the baseline. The first bar is bar number ‘0″ and represents how muchBlack you have in the photo. Not “nearly black”, or “almost black” but proper, absolute “black”. It’s called the Black Point. If there’s a lot of black in the photo this bar will reach a long way up the chart. If there is hardly any black at all it will barely get off the baseline. In the illustration above, there is no black at all indicated at bar “0” – the extreme left side of the baseline. So the height of each bar along the baseline indicates “quantity”.

At the extreme right end of the baseline is the “White Point”. This is tone value 256. The white point is not “nearly white” or “off-white” – it’s completely, absolutely white! In the histogram above, you can see there is a bit of “white” at the white point.

Between the Black Point and the White Point are all the other tones in the photo, ranging from nearly black, through to dark grey, mid grey, light grey, nearly white and finally white itself at the white point – 256 tones in the grey scale. Remember that how much of each tone you have is indicated by the height of each point along the scale. The middle tone – tone value 128 – is called the “Grey Point”. The histogram above indicates that the most amount of tone in the photo is mid grey or to put it another way – the mid tones.

What do we mean by tones?

The histogram above is not measuring colour – it’s only interested in “tone”, in other words, how light or dark parts of the photo are. If you shoot a colour photo and then turn it into a black and white photo, you get rid of the colour and are left with with a range of tones that we refer to as “greyscale” – ranging from black to white. This is what the histogram is looking at. The histogram shows us, very accurately, how much shadow, mid-tone and highlight our photo contains and how it’s spread out between black and white.

When we talk about a photo having a “full dynamic range” what we mean is that the photo contains a good range of tones from black, through the mid-tones to white and will therefore have good contrast. Like this photo above.

If however, the dynamic range is compressed – for example it might start at the black point but stop at or around the mid-tone area (value 128) – then there would be no highlights in the photo – no light areas. The reason for this might be that you filled the entire frame with a photo of a black wall! Or, more likely you have under-exposed the photo! Like the photo below. A correctly exposed photo will nearly always contain some highlights.

What about if the photo’s histogram starts over at the white point and only gets as far as the mid tones – but has no shadows? Chances are, you have over-exposed. Like this…

How to use Histograms pro-actively (highlight and shadow warnings).

Histograms are about more than just judging over or under exposure. When we over-expose an image and the white point is crowded, we call that “clipping” the whites. Same thing with the under-exposure – then the blacks get “clipped”. Clipped blacks can lead to noise and banding in the shadow areas when you try to rescue the photo with your editing software but clipping the whites is much worse.

In an over-exposed image, the white areas contain no information at all – the camera is unable to process the pixel data because it’s overloaded with light and so you get areas of the photo that are effectively empty! Because there is no data there, you can’t rescue the photo. Trying to adjust the image on the computer just results in large patches of grey tone because the computer has no idea what should be in these “empty” areas.

Fortunately the camera is equipped with highlight warning and sometimes also withshadow warning. You turn these options on in the menu system on your camera and the result is a flashing patch over areas of the photo that have been “clipped” showing you exactly where the over exposure (and under exposure if you have that option) are occurring. Now you can adjust your exposure and re-shoot to try and minimize the problem. And the great thing is, the histogram will allow you to see exactly how far you can go with either more or less exposure before you run into problems.

In the photo below, I have purposely pushed the highlights and shadows in order to show the highlight and shadow warning – highlight is red and shadow is blue – your camera will more likely use black and blue. Notice the histogram is “clipped’ at both ends.

Using the histogram pro-actively allows you to maximize the best possible tonal range for your photo, allowing you to set an exposure that gathers the largest range of tones between the black and white points, before you start to clip either of them. You can’t do that by glaring at the photo on the back of the monitor!

Week 4 ISO

This week we will be learning about:

• The exposure triangle and ISO
• Reviewing your photography for assignment 1
• Launching assignment 2

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http://youtu.be/KQw28-3LEU4

The final piece in the “exposure” jigsaw is ISO. What is it and what does it do?

ISO is measure of the cameras sensitivity to light. You may remember it from shooting film, where we sometimes called it “film speed’.

ISO, then:

“The ASA and DIN film speed standards have been combined into the ISO standards since 1974. The current International Standard for measuring the speed of color negative film is ISO 5800:2001^[16] (first published in 1979, revised in November 1987) from the International Organization for Standardization (ISO). The determination of ISO speeds with digital still-cameras is described in ISO 12232:2006 (first published in August 1998, revised in April 2006, and corrected in October 2006)”.

Source: Wikipedia, http://en.wikipedia.org/wiki/Film_speed

So now you know!

Seriously though, ISO as it relates to photography, and in this case DSLR’s is a vitally important factor in determining correct exposure and manipulating shutter speeds and aperture values in order to achieve our creative goals.

ISO is a measure of how sensitive or insensitive the camera’s ccd or digital sensor is to light. A high ISO number indicates a high sensitivity and thus the camera needs less light to “see” the photo, whereas a low ISO number indicates low sensitivity, now the camera needs a lot more light to “see” the photo.

High ISO

When shooting film, the ISO is sometimes referred to as “film speed” and a high speed film or fast film is useful for shooting dark subjects, in dark locations or in very low levels of light – indoors or in poor light. Also because the film is “fast” – it reacts to light very quickly – it doesn’t actually need as much exposure in normal levels of light so you can get away with using a much faster shutter speed (to stop action) and/or a smaller aperture (for better depth of field). A lot of sports photographers exploit this by using faster films to shoot action in order to use faster shutter speeds.

The switch to digital cameras carries with it the idea of ISO and fast or slow films, but now the ISO value is a measure of how fast the digital sensor reacts to light. And being an electronic device, we are able to turn the sensor’s sensitivity up or down, higher or lower, and we can do it any time we like. We can shoot frame 1 at 100 ISO, frame 2 at 200 ISO and frame 3 at 400 ISO if we want to. A normal ISO speed for most general photography would be 200 ISO or 400 ISO for a little extra shutter speed.

Film grain & digital noise

So if a high ISO setting is great for getting faster shutter speeds and better depth of field, why don’t we just use a high ISO all the time? Well, like so many things in life, there’s no such thing as a free lunch.

Fast films have the problem of film “grain” in that the higher the ISO, the faster the reaction time of the film emulsion and “grainier” the final image looks. In DSLR’s, the problem isn’t “grain”, it’s electronic noise – leakage currents – that produce noise in the form of speckles, a mozaic-like pattern across the image area and possibly some banding. In simple terms, as you push the sensor to a higher level of sensitivity, the pixels or light gathering areas on the sensor work harder, create more electric current and get hotter – which generates noise. Large sensors (like full frame or FX cameras) handle noise much better than small sensors because of their increased surface area.

Small sensors, like compact cameras struggle with noise issues because their sensors are so much smaller in surface area but full frame DSLR’s are good at using high ISO values these days – they optimize the large surface area of the sensor.

 

(Above). The photo above is a full frame shot on a Nikon D700 at 6400 ISO. The photo below it is tight crop of just the head and shoulders. Can you see the noise? You can a bit but for 6400 ISO it’s pretty impressive. The D700 is an FX or full frame camera with a big sensor and it’s one of the best cameras available for handling high ISO’s.

 

 

(Above). The photos above show the full frame and then a tight crop of a night scene shot with a Nikon D200 at 800 ISO. Notice how much more noise there is with the old D200 with it’s smaller  Dx sensor.

Low ISO

We can also dial in a low ISO value – 100 or 200 ISO for example, some cameras can go lower still. Low ISO values are great for keeping the optimum quality of an image by virtually eliminating noise and creating smooth transitions of colour, tone and contrast in the photo. This is exactly what a good landscape or portrait photographer will look for most of the time. Of course, a low ISO setting could mean that in low light levels you might be forced to use a tripod as the shutter speed slows right down, even when the aperture is wide open. Landscape photographers don’t mind this – they nearly always work off a tripod anyway and achieving a slow shutter speed is often an advantage, it enables motion blur in things like waterfalls, rivers, the sea rushing in and out on the beach, trees in the wind and so on and adds to the creativity of the photograph.

ISO Progression

The standard progression of ISO settings looks like this:

100, 200, 400, 800, 1600, 3200, 6400

It’s neat isn’t it? Do you see how the numbers just double each time?

In fact, as each ISO value doubles we are actually increasing the exposure value by exactly double. 200 ISO will give us twice as much exposure as 100 ISO. 800 ISO is twice as much exposure as 400 ISO but half as much exposure as 1600 ISO.

We’ve come across this idea of “halving” and “doubling” exposure already of course. If you remember, the difference between each full stop of shutter speed is exactly half or double; and the difference between each full stop of aperture value is also half or double.

How do ISO, shutter speeds and apertures work together to achieve correct exposure?

So all three systems, shutter speeds, apertures and ISO all share this common attribute – they all three half or double exposure as you increase or decrease from one full stop to the next.

Let’s see how that might work:

image that you are out on a bright sunny day, taking some photos of a pretty view – average light, average subject. The camera might well tell you that a correct exposure is f8 at 1/250 second if you have your camera set to 200 ISO.

We’ll put that in bold on our chart below:

f2.8 – 1/2000

f4    – 1/1000

f5.6 – 1/500

f8    – 1/250

f11  – 1/125

f16  – 1/60

f22  – 1/30

You’ll see from the table that I’ve drawn, that although you can shoot your picture at f8 at 1/250, by opening up the aperture by one stop (f5.6) and at the same time increasing the shutter speed by one stop (1/500) you can also get a perfect exposure.

Because both aperture and shutter speed half or double exposure, if you double one you can halve the other and retain exactly the same exposure value! Except that now you have changed the speed and the depth of field – you have a faster shutter speed (good for stopping action) but a shorter depth of field (good for isolating a subject).

You can carry on through the table and see all the possible combinations of aperture and shutter speed that might be available to you if you were starting with an base exposure of f8 at 1/250. In fact, if you go to the extreme ends of the table you will see that you could opt for f22 – 1/30, great for landscapes using a tripod, you get maximum depth of field and a bit of motion blur to create lovely effects with movement as in waterfalls etc. Or, you could use f2.8 at 1/2000 second, great for portraits using minimum depth of field to blur the background, or for sports action where the fast shutter speed would freeze the action and the short depth of field would isolate the subject.

For any given lighting situation there will be a table of possible combinations that you could build, just like this one, that will show all the possible combinations of shutter speed and aperture that you could use – you just have to select which one suits your purpose the best.

But this is just the table we could build at 200 ISO.

What if we alter the ISO by 1 stop to 400 ISO? Or 2 stops to 800 ISO?

OK, in which case instead of f8 at 1/250 the correct exposure would be f8 at 1/500 because increasing the ISO by 1 stop doubles the exposure, in other words over-exposes by 1 stop and in order to get it back to where it should be we have to increase the shutter speed to halve the exposure by the same amount, 1 stop.

200 ISO                               400 ISO                  800 ISO

f2.8 – 1/2000                      f2.8  – 1/4000       f2.8 – 1/8000

f4    – 1/1000                      f4     – 1/2000       f4    – 1/4000

f5.6 – 1/500                       f5.6   – 1/1000       f5.6 – 1/2000

f8    – 1/250                      f8     – 1/500       f8   – 1/1000

f11  – 1/125                        f11    – 1/250        f11  – 1/500

f16  – 1/60                          f16    – 1/125        f16  – 1/250

f22  – 1/30                          f22   –  1/60          f22  – 1/125

Or we could compensate by altering the aperture rather than the shutter speeds, in which case;

f8 – 1/250 at 200 ISO becomes f11 at 1/250 at 400 ISO or f16 at 1/250 at 800 ISO.

So exposure is triangle of settings using shutter speeds, apertures and ISO all together to achieve the effect that you want. But remember, high ISO = noise so we tend to keep the ISO values down unless we really need to increase them.

Auto ISO

A great way of managing ISO is to use the cameras Auto ISO setting in the camera’s custom menu or ISO menu. Turning the Auto ISO ON allows the camera to automatically increase the ISO setting whenever the shutter speed looks like dropping below the threshold for camera shake, or a level that you specify in the custom menu. This way, you reduce the risk of camera shake, retain the lowest ISO settings for quality until you really need to change up and the camera does it for you in the background leaving you free to concentrate on your photos. There are times when you will want to take back control of the ISO settings of course, using flash would be one, or when you see the auto ISO setting a very high ISO value that you don’t want to use, so you need to keep an eye on what ISO value is actually being used by the camera all the time – after a while this becomes second nature.

Week 3 Apertures

This week we will be learning about:

• Apertures for depth of field
• Reviewing student tumblr blogs
• Giving feedback on your research and planning for assignment 1

Apertures. What are they, what do they do for us and how do we use them?

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A  YouTube video about depth of field is here:

http://youtu.be/OUYuUs1aaCU

plus:

http://youtu.be/73Yx4NnXPRg

APERTURES

Lets start with apertures.

Aperture Progression

Here’s an illustration of the lens’s apertures or f-stops, from f1.4 (very wide or big) to f22 (very narrow or small).

A typical progression of full aperture stops would look like this:

f2.8, f4, f5.6, f8, f11, f16, f22.

You should try to learn this progression – it is part of the language of photography. You will also come across other f-stop numbers on your camera; f10 and f13 for example – these are third stop or half stop intervals between the full stop values. f13 is just f11 and an extra third. You can sometimes program your camera in the custom functions to increase your apertures in full stops only, in half stop increments or in third stop increments which is usually the default value as it increases your fine control over exposure.

Each full stop or Aperture halves or doubles the amount of exposure – this is important – you must remember this!

So, f8 is twice as much light as f11 but half as much light as f5.6

The aperture is housed in the lens body itself and is controlled via a thumb wheel on modern DSLR cameras, sometimes in conjunction with a small button on the top plate, normally the exposure compensation(+/-) button with an aperture symbol next to it like this:

Setting Apertures on the Camera

To change aperture in Aperture Priority and Manual mode you just press the button whilst turning the thumbwheel and watch the apertures display in the viewfinder. You will notice in the illustration that wide apertures have small numbers (f1.4) and narrow apertures have big numbers (f22). A lot of people get confused by this. Where do these numbers come from – what do they mean? The answer is that they are a mathamatical formula – a pretty simple one actually;

f-stop = the diameter of the aperture divided into the focal length of the lens.

e.g if the diameter of the aperture is 5mm and the lens you are using is a 55mm lens, divide 5mm into 55mm and you get?…f11.

So an f-stop is not a fixed size, it varies from lens to lens, but the key fact is that all lenses when set to f11, or f8 or any other f-number will all be transmitting the same amount of light and hence will all give the same exposure.

What are Apertures really for?

OK, now we know what they are and where they come from but what do they actually do? Clearly they control how much light enters the camera – a big aperture lets in a lot of light, a smaller one reduces the amount of light and so alters exposure. Apertures are obviously a fundamental tool for controlling exposure but then, so too is shutter speed. Why do we need two systems for controlling exposure? Why not just have a single aperture and lots of different, variable shutter speeds – wouldn’t that be enough to control exposure? Actually it would, and that’s exactly how a pin-hole camera works – one aperture, the pin-hole and variable shutter speed (how long you leave the pin-hole uncovered). And it works just fine.

Apertures give us something else – something more important and more useful than merely controlling exposure – they allow us to control depth of field.

DEPTH OF FIELD

What is depth of field?

I’ll give you my own definition:

Depth of Field (DOF) is a ZONE of SHARPNESS, that extends IN FRONT OF and BEYOND the point that you actually FOCUSED on.

Like all ZONES it has a beginning and an end. It has boundaries. There is an area leading into sharpness and an area leading out of sharpness. Then there is an area around the subject that you focused on, where everything seems to be perfectly sharp.

And this zone of sharpness is relative to how close you are to the subject. If you are very close to the subject, the zone is very, very small. If you are a medium distance from the subject the zone is much bigger and if you are a long way from the subject the zone of sharpness may in fact reach as far as the eye can see – to infinity actually. So DOF is a relative value.

Examples of the use of Depth of Field

1. In this shot of a restaurant interior, the depth of field needs to cover the foreground and extend to include everything up to the back wall and fireplace. Wide angle lens, focused on the foreground napkins, at f16.

 

2. In this landscape, everything must be included in the depth of field from front to back. Wide angle lens, focused about third into the frame, f22. (The blurred water is due to long shutter speed – use a tripod!)

3. In this shot of motorway light trails, there is no foreground detail to worry about and the subject is a long way away so depth of field is not critical. Wide angle lens, focused on the background, f8, tripod.

4. in this shot, the short depth of field helps to isolate the subject (the wine glass) and create a mood. Telephoto lens, fairly close to the subject at f2.8.

How does it work?

Before we go any further, consider focus for a moment. When you focus on an object, you also see a zone of sharpness around the object you focus on – this is the Depth of FOCUS. It’s a three dimensional thing – focus has a beginning a middle and an end. It’s also a relative value.

Try holding your finger up in front of your face. Focus on the knuckle. Notice how the background is thrown way out of focus when you look at your finger? Now look out of the window across the garden at an object – the garden gate would be a good choice. Notice how much more of the area around the gate is focus compared with your finger experiment? Look at a farm across the valley and you’ll notice that nearly everything in your filed of view is in focus. So Depth of FOCUS is relative to how close you are to the object you are focused on. Close up you get almost no Depth of Focus, more distant and get a lot more.

Now, Depth of FIELD (DOF) is the ability of the lens to GROW that ZONE OF SHARPNESS by using a smaller and smaller aperture. We can control how big this zone is by altering the aperture size – it’s a characteristic of apertures that the smaller they are the larger the DOF they create. A wide aperture ((f1.4) will not grow the existing depth of focus by anything at all, but a small aperture (f22) will increase the zone of sharpness, the depth of focus, by a massive amount – and this is what we call depth of field. And it’s still relative to how close you are to the subject.

If you photograph a subject that is very close to the camera lens you will get a tiny depth of focus, and even when you use a small aperture, f16 or f22 the resulting increase in depth of field will still be relatively small. But if you photograph a subject that is further away, you will get a bigger depth of focus and then by using a small aperture you will achieve a much, much bigger depth of field.

It’s all relative to SUBJECT-TO-CAMERA DISTANCE.

Let’s re-cap then.

• The widest aperture (f1.4) = minimum DOF
• The smallest aperture (f22) = maximum DOF
• Get close to a subject to reduce DOF
• Get further away to increase DOF
• Wide angle lenses exhibit a lot of DOF
• Telephoto lenses exhibit reduced DOF

1. A Wide Angle Lens,medium distance  and small aperture (f16)= A large depth of field

2. A telephoto lens, short distance and wide aperture (f2.8) = a short depth of field.

Incidentally, that last one, about lenses, why is it that wide lenses have better DOF than telephoto lenses? Well one reason is that a telephoto magnifies a distant image, in effect bringing it much closer to you – as though the camera-to-subject distance was reduced, whereas the wide angle lens pushes the subject away from you, as though the camera-to-subject distance was increased.

So if you absolutely wanted to guarantee a small depth of field, use a telephoto lens, get close to the subject and use  the widest aperture!