Digital Camera Magazine - Master Exposure

Complete photography guide

Master

Exposure TAKE STUNNING PHOTOS USING OUR EXPERT TIPS ■ How to read a histogram ■ Metering for different tones ■ Coping with unusual lighting

VITAL SKILLS GUIDE

Master

Exposure Trying to get the ‘correct’ exposure is one of the greatest challenges for those beginning in photography. But it needn’t be. This book will show you the pitfalls to avoid, when to alter your camera’s settings (and by how much) and how to get creative with metering.

Exposure

3

Master

Exposure TAKE STUNNING PHOTOS USING OUR EXPERT TIPS

Contents ■ Exposure basics

p10

■ Adjusting exposure

p14

■ When things get tricky

p16

■ Master of exposure: Ansel Adams

p20

■ Background problems

p22

■ Unusual lighting

p26

■ Master of exposure: Galen Rowell

p30

■ How to read a histogram

p32

■ Controlling the dynamic range

p36

■ Using a neutral density grad

p38

■ Master of exposure: Pål Hermansen

p42

■ Low light exposures

p44

■ High key/low key

p46

■ Top 10 tips

p49

Exposure

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Use your grey matter T

he biggest advantage digital has over film is the fact that you can check your shot once you’ve taken it. You can bring up a histogram to check the brightness range of a scene – and make sure you’re not underexposing or overexposing it. You can, if your camera allows, switch on a flashing highlight to show you any blown highlights where detail will be lost in your photograph. You can then change your exposure accordingly. And if all that fails to produce the balanced exposure you want, you can go some way to rectifying it while image-editing. It is, however good to get things right first time – to produce a high-quality image in-camera which you only have to do minimal tweaking with later. This book arms you with practical advice for getting the exposures you want, and the confidence to take control when the camera’s being fooled. We’ve got clear examples of when this can happen and what you should do. We also show you the inspiring work of three master photographers to give you an idea of you what can be achieved once you’ve nailed the basics – which start on page 10…

Marcus Hawkins Editor, Digital Camera Magazine

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Exposure basics O

n the face of it, exposure seems a pretty straightforward business. In order to produce a good range of tones in your picture, the camera has to make sure the right amount of light reaches the sensor. And it does this (or you do) by adjusting the length of the exposure (the shutter speed) and the light intensity (the lens aperture). The image is formed by the accumulation of light on the sensor during the exposure. All digital cameras incorporate exposure systems which will do this automatically, so what’s the problem? Even the most sophisticated metering system is unable to understand what the camera’s looking at, or what the photographer’s intentions might be. This is where you need to take control.

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Digital’s dynamic range

Mid-tones

Cameras will struggle to deal with scenes where there’s an extreme brightness range. With film, this is called ‘exposure latitude’, with digital cameras it’s called ‘dynamic’ range. On a very bright sunny day, it may be impossible to find an exposure which records some detail in the shadows without ‘blowing out’ the highlights, or vice versa. It’s generally agreed that digital cameras have a similar exposure latitude to slide film, and you can start off by assuming a dynamic range of about 4 EV values. This means you should still be able to see or recover useful shadow detail 2 EV darker than the mid-tones in your image, and highlights 2 EV brighter than this mid-tone value should record well too. So what do you do if the brightness range in the scene exceeds this 4 EV range? There are ways of dealing with this, and we look at these a little later on.

The idea of ‘mid-tones’ is important in exposure. On one level, it describes areas of the scene which are more or less in the middle of the tonal range. You might say these are the parts you want to expose correctly. But how dark or light are these mid-tones? In order to work out the exposure, your camera has to work to a standardised average ‘grey’ tone – 18% grey, to be precise – and try to adjust the exposure to reproduce your subject with this level of brightness. This is one of the principle drawbacks of all built-in camera meters, no matter how sophisticated. They don’t know what it is they’re looking at, and what intrinsic tone the subject ought to have. All subjects will be reproduced to this 18% grey value, which is a problem we’ll come on to shortly.

At first glance, this scene seems to average out an overall mid-tone. However, the bright wall of the cottage is overexposed. Dialling in some underexposure would take the edge off this, at the expense of detail in the shadows.

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Metering patterns

Aperture and shutter speed

Light meters may not be able to understand that different subjects may have different intrinsic brightness levels, but camera makers have at least been able to allow for difficult and contrasty lighting conditions. By default, digital cameras use ‘multi-pattern’ metering systems that measure the light values at numerous points in the scene. This helps them build up a picture of the type of lighting you’re shooting in, and the camera may adapt automatically to backlighting, for example. Multi-pattern metering systems are hard to second-guess, though, and many photographers prefer simpler ‘centre-weighted’ metering, which averages the whole scene but places extra emphasis on the central area. Spot metering is very specialised. It takes a reading from a very small area of the scene only.

Digital cameras control exposure using both shutter speed and aperture. Why both? Wouldn’t one or the other do the job? There are creative advantages to these two means of exposure control. Smaller lens apertures offer more depth of field (near-to-far sharpness), while fast shutter speeds let you freeze fast-moving objects. Shutter speed and aperture are interchangeable, so that if you want to use a smaller lens aperture, you can compensate with a longer exposure. Or, if you want a shorter exposure, you simply set a wider lens aperture. For example, if your camera indicates an exposure of 1/250sec at f/8 but you want to shoot at 1/1000sec, which is two stops, or EV values, faster, you need to increase the aperture value by two stops as well, to f/4. Some cameras allow you to adjust shutter speed and aperture values in 0.3 EV steps, but the same principle applies – a change in one must be mirrored with a same-sized change in the other.

To blur the crashing waves in this scene, a smaller lens aperture has been selected in order to obtain a slow shutter speed.

When faced by a mid-tone scene such as this, multi-pattern metering systems can be trusted to produce wellexposed photographs.

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Exposure

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Adjusting exposure S

o how precise do you have to be with exposure? Even though digital cameras only have a certain amount of ‘exposure latitude’, in practice there are many different ways of interpreting a scene, and many exposure errors can be rectified or at least improved with a bit of image-editing. To give you an idea of how the subject brightness changes with exposure, here’s the same scene at seven different exposure values, all shot at the same lens aperture, but with shutter speeds 0.5 EV apart. These also demonstrate the idea of exposure latitude and dynamic range. There isn’t one shot where detail’s been recorded both in the foreground and the garden outside – the scene is outside the dynamic range of the camera’s sensor. You might prefer the ‘overexposed’ shot because it shows the subject’s face with a nice high-key effect, or a darker silhouetted version. Or you might open one of the in-between shots in Photoshop and attempt to balance the tones more evenly.

The shot with the biggest increase in exposure works well – it ‘bleaches out’ a potentially distracting background. 14

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+1.5 EV

+1 EV

+0.5 EV

0 EV

-0.5 EV

-1 EV

-1.5 EV Exposure

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When things get tricky W

e explained in the previous section that camera exposure systems could adapt to a degree to ‘difficult’ lighting, but that they had no sense of the intrinsic lightness or darkness of specific subjects. But does this really make much difference? Indeed it does. If any of your digital camera shots come out badly exposed, it’s often the intrinsic brightness of the subject that’s caused the problem, not ‘difficult’ lighting or any error on your part. Just to show you how much difference intrinsic subject brightness does make, we’ve arranged a series of still-life experiments…

Metering for dark tones/black We used a black background for this shot of an ornamental elephant, which itself was a mixture of dark red and black. The camera didn’t know any of this, of course. All it could do was measure the amount of light it ‘saw’. Not surprisingly, this wasn’t very much! As a result, the camera increased the exposure. Remember, all it can do is attempt to render the subject as an overall 18% grey tone, because while you and I might realise the elephant and the background is black, the camera doesn’t have the cognitive powers of the human brain. It’s dark, increase the exposure. That’s the limit of its thinking. The result isn’t too hard to predict; an 18% grey elephant against an 18% grey background.

No Adjustment

The black background and dark subject fooled our camera’s meter. Left to its own devices, it overexposed by 2 EV.

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-2 EV

Watch out for highlights Our elephant shot reveals something else that’s interesting, too. In the overexposed version, look at the dried flowers in the foreground. They’re actually close to an average 18% grey tone in real life, but because the camera’s increased the exposure, they’ve been almost completely burned out. However, by manually overriding the exposure and reducing it by 2 EV, we’ve not only restored the elephant and the background to a ‘proper’ black, we’ve restored the correct tones to the dried flowers. The same will apply if you’re photographing black birds with bright beaks, for example. When you’re photographing dark-toned subjects, the camera will often increase the exposure and lose highlight detail in other parts of the scene. The subject’s darkness doesn’t have to be as extreme as that in our example. If you’re shooting dark-toned vegetation, for example, reducing the exposure by 0.7 EV to 1 EV is often a good idea to preserve the depth of colour and highlight detail.

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Metering for light tones Unusually dark-toned subjects are not an everyday problem. Light-toned subjects are far more common, and they typically distort the camera’s meter reading to a greater degree. Our still life shot demonstrates this well. The ginger, onions and squash are all

fairly light-toned, along with the cloth beneath them, but even so you might expect the camera to expose them correctly without any help. The result, though, is distinctly dull and gloomy. Only by reshooting with +0.3 EV compensation were we able to restore a realistic-looking brightness to the

No Adjustment

These vegetables are lighter-toned than the average 18% grey looked for by the camera’s meter, so we needed to apply EV compensation to make sure this is how they were reproduced.

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+0.3 EV

shot. At first you might need to experiment a great deal to find appropriate EV compensation values for light or dark-toned subjects. But with practice, and a growing understanding of your camera’s behaviour, it gets a lot easier to work out when to override the camera and how much by.

No Adjustment

+2 EV

If you’re photographing anything white, beware! Your camera’s meter will attempt to reproduce it as a muddy grey, so you need to intervene. This shot required +2 EV exposure compensation to look ‘right’.

Metering for white White subjects are a special case, and the cause of the most severe underexposure problems. They’re a special case because the world is full of white objects and backgrounds, and because you might be surprised at just how bright they are. This still

life demonstrates this very well. Remember, we want objects to appear in photos as they do in real life, and not reduced to the 18% grey assumed by camera meters. Our first attempt, shot using the camera’s default exposure reading, was a disaster. Indeed, the overall tones are very similar to those of the

default black elephant shot, demonstrating how the camera attempts to reduce all tones to the same value. In order to reproduce the whiteness of our subject, we had to increase the exposure value by 2 EV. You’ll have to do the same with snow scenes, for example, or close-ups of wedding dresses.

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Master of exposure Ansel Adams

T

here can’t be many people who’ve never seen an Ansel Adams photograph. He is the acknowledged master of landscape photography. He achieved so much before his death in 1984 of heart failure at the age of 82. Adams was both a photographer and conservationist and started the f/64 group (an association of Californian photographers who promoted ‘pure’ photography) with Edward Weston in 1932. He’s perhaps better known for developing the ‘zone’ system for exposure, a technique which enabled him to visualise how he would print the various parts of the image, and expose the negative accordingly. The tonal range he managed to extract from his black and white film was simply incredible.

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© Corbis

This is unmistakably an Ansel Adams landscape. The richness, depth and detail is astounding, the exposure capturing every nuance of light. It pictures the Tetons and Snake River in Grand Teton National Park, Wyoming, and was shot in 1942.

To learn more about Ansel Adams, pay a visit to anseladams.com. Exposure

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Background problems I

t’s not necessarily the subject of your photograph that can give you exposure headaches. The tone of the background is just as important, and can have a big influence on the exposure reading. Even if your subject consists of fairly even mid-tones, an unusually light or dark-toned background can produce exposure errors. The size of this error will depend on how much of the frame is taken up by the background. It can also be hard to

judge exactly how much emphasis the camera is giving to the subject itself, since multipattern metering systems may concentrate on the object in the middle of the frame, which may or may not be where your subject is.

Size matters This shot uses a mid-tone subject set against a dark background, but shot at two different zoom settings, so that in one the onions and

ginger take up nearly all of the frame, while in the other they’re quite small relative to the background. In both cases the camera’s default auto-exposure readings were used. The close-up shot is correctly exposed, but in the zoomed-out version, the larger proportion of dark background has fooled the camera into overexposing by 1.3 EV. We tried the same experiment using a light background. By zooming right in on the

You may not encounter completely black backgrounds like this when you’re out shooting, but dark tones will have the same effect.

Light backgrounds cause mid-toned subjects to underexpose if they’re not big in the frame. Bear this in mind when framing people against pale skies. 22

Exposure

artificial fruit, we’ve excluded nearly all of the background, and the resulting exposure is pretty well spot-on. When we zoomed out, though, the proportion of the frame taken up by the background was far higher, leading the camera to reduce the exposure by 1.3 EV, which has left the shot underexposed. The degree to which the background influences exposure will depend on the amount of the frame it takes up and its brightness, but it can make a big difference.

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Complimentary tones Here’s another experiment showing how the exposure changes when you place a dark subject against a light background. In this case the best exposure is the middle one, because the light background has reduced the exposure. This helps render the dark tones of the lenses more accurately. You can also see what happens when you place a light subject against a dark background. The results are similar. Close-up, the while flowers and vase in our set-up cause the camera to underexpose. In the wideangle shot, the dark background has caused overexposure. The middle shot is the best because the tones average out well.

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Exposure

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Unusual lighting J

ust to make life that little bit more awkward, it’s often the most dramatic and ‘difficult’ lighting that makes the most exciting photographs. You face two challenges here. The first is that the brightness range of the lighting will often exceed the dynamic range of your camera’s sensor, so you have to decide which is the most important part of the scene and base the exposure on that, leaving extreme highlight or shadow detail to disappear. Once you’ve done that, you need to work out how to take an exposure reading that will render the important part of the scene properly.

Backlit images can be some of the most exciting, but they also provide plenty of exposure headaches. Most compact digital cameras will favour shadowed foreground subjects, like our pedestrians, and this compromise has worked out well here.

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Backlit subjects With backlit subjects, the light’s coming from behind your subject and towards the camera. This means that the side of the subject facing you is in shadow against a bright background. It’s unlikely that your camera will be able to record detail in the subject and a full range of tones in the bright background too, so you’ve got a decision to make. You can expose the shot to get detail in your subject, and render the background as a brilliant, ethereal white, or go for a silhouette effect, as you might with a dramatic sunset, for example. In both cases, spot metering can be the most reliable solution because multi-pattern metering systems can behave a little unpredictably. Some are designed to give priority to subjects in the centre of the frame, especially with the tonal distribution characteristic of backlighting (the camera can detect this). You may get a properly exposed subject when you wanted a silhouette, and vice versa.

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Sidelit subjects Sidelighting is less difficult to deal with. The overall contrast tends to be lower because you’re not shooting into the light. However, the long shadows cast by the light can influence the meter in ways you don’t want. Digital cameras, especially non-SLR models, seem to favour shadows over highlights in a scene, so you can often end up with an overexposed image with ‘blown’ highlights and shadow detail that’s too light. The strong, textural quality of sidelighting, however, relies heavily on deep shadows and richly-coloured highlights. It’s a good idea with sidelit subjects to at least bracket your exposures, or take one at the default meter reading and then another with -0.3 EV or -0.6 EV compensation. With digital cameras, a little underexposure is a lot easier to correct later than overexposure. Blown highlights are lost for good, but you can often extract an amazing amount of colour and detail from gloomy shadows.

If you want to capture the full richness of colour and textural quality of sidelit subjects, you may have to manually reduce the exposure to retain those dark shadows. 28

Exposure

Spotlit subjects Spotlit subjects are particularly difficult to deal with. The situation here is comparable to that we set up when photographing subjects against a dark background, but the contrast in tones is going to be even higher. Left to its own devices, the camera will attempt to compensate for the darkness of the background, leaving your main subject hopelessly overexposed. The solution here is to take a spot reading from the area being spotlit. In addition, you’ll have to make allowances for the intrinsic brightness of your subject, which is one of the reasons why spot metering is quite a skill. For example, if you’re photographing a performer on stage in a white costume, you might need to take a spot reading from the costume, then dial in +2 EV exposure compensation to make sure it reproduces as white. Landscapes spotlit by the sun breaking through clouds are generally easier to meter for, thanks to their more mid-toned nature.

Spotlit subjects are one of the trickiest to expose for, but spot metering can help you out. Be careful of metering from intrinsically light or darktoned objects, though. Exposure

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Master of exposure Galen Rowell

T

he world lost of one its greatest wilderness photographers on August 11th 2002, when Galen Rowell – and his wife Barbara – died in a plane crash in California while returning from a photo workshop in the Arctic. He was 61. Rowell was a perfectionist when it came to his photographs. His search for the ‘dynamic landscape’ meant seeking out the best light and having the confidence to control it. Such was his mastery of exposure, he had his own branded range of graduated neutral density filters, developed by Singh-Ray. Rowell started out as a car mechanic, but gradually began to fuse his passions of mountain climbing and photography into a successful career. In 1972 he received his first commission from National Geographic – to capture an ascent up Yosemite’s Half Dome monolith. The photographs he brought back proved so powerful that one was selected as the cover shot. He went on to shoot numerous stories for the magazine and publish an impressive series of books, including the legendary ‘Mountain Light’ – the name he went on to use for his photography business – and ‘My Tibet’, co-written with the Dalai Lama. He received the Ansel Adams Award in 1984, for his contributions to the art of wilderness photography.

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While Galen Rowell rose to prominence with his staggering images of mountains, he was a master craftsman of landscape and wildlife photography as well. This shot of sunflowers taken in the eastern Sierra, California, in 2000 shows how skilled he was at reading light. The strong backlight and delicate form of the flowers have been captured with perfection. The use of a graduated filter has tamed the harshness of the top part of the frame, making the dynamic range of the scene more manageable. The resulting image takes your breath away.

See more of Galen Rowell’s awe-inspiring work at www.mountainlight.com. Exposure

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How to read a histogram S

o far we’ve been basing our assessments of exposure levels on the appearance of images on a screen or in print. There’s a more technical way of assessing the tonal balance of digital images, though, and that’s using a histogram. Many cameras can display ‘live’ histograms as you compose a shot and/or histograms for saved images. You can display a histogram in Photoshop and other image-editors, too. The histogram will tell you whether you have ‘blown’ highlights, blocked-in shadow detail, whether there’s a full range of tones, and how light or dark the image is overall. It’s basically a bar chart (though with so many bars they blend into a continuous curve) showing how many pixels there are for each brightness value across the tonal scale, from dense black to brilliant white.

The perfect spread of tones You may hear people talk about the ‘ideal’ histogram, but in practice histograms can come in many different shapes, depending on the tonal balance in the image. What you would want to see in a histogram, though, is the histogram curve tailing off to zero more or less exactly at the far left-hand (shadow) end of the scale and again at the far right (highlight) end. That’s exactly what we’ve got with our sample shot here. However, if the histogram is chopped off at the left, that means there are areas of solid black,

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or blocked-in, detail-free shadows in the image. If the histogram is chopped off at the right, you’ve got ‘blown’ highlights, which are areas of featureless white. If the histogram’s been chopped off, or ‘clipped’ at either end, there’s nothing you can do to bring that image detail back.

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Unusual histogram shapes The ‘typical’ histogram tails off at the left and right-hand ends, but swells to a maximum somewhere round the middle. Some subjects, though, produce very different results. If you shoot a shadowed subject against a bright sky, you might get two ‘peaks’, one in the shadows, one in the highlights, and practically nothing in the middle. There’s nothing wrong with your exposure technique, it’s just characteristic of this type of subject.

‘Flat’ histograms On overcast days, or in other situations where there’s not a lot of contrast, you might end up with a histogram that tails off to zero long before the left and right-hand ends of the scale. This is a characteristic of flat-looking images. As the histogram shows, there are no really dark or really light areas, which is a problem because photographs usually rely on a full range of tones for depth and richness.

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Exposure

Clipped shadows Histograms can reveal obvious flaws in your images. This shot has been underexposed, and this has moved the whole histogram to the left, with the result that the shadows have been badly clipped, while there are no real bright highlights (the histogram doesn’t reach the right-hand end of the scale). You can adjust the image in Photoshop to restore brilliant white highlights, but you can’t do anything about those lost shadows.

Clipped highlights This image has the opposite problem. It’s been overexposed, with the result that the whole image histogram has effectively been moved to the right. Even though we’ve recorded the shadow detail nicely, the highlight end of the histogram has been clipped, just as the histogram curve is rising, indicating the presence of lots of bright tones in the sky. These tones can’t be recovered.

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Controlling the dynamic range E

arlier, we mentioned the idea of dynamic range – the range of tones your digital camera’s sensor can record. This ties in with our look at histograms in the previous section. You can think of your camera’s dynamic range as an ‘exposure window’. Your job is to try to get the full range of tones in your subject into this window. As we’ve seen, if the brightness range is too high, you have to decide whether to sacrifice extreme highlight or shadow detail, depending on what you consider to be the main subject. This isn’t the only alternative, though. There are things you can do to reduce the contrast range in the scene at the time of shooting.

Fill flash is a useful way of ‘balancing’ extremely high contrast scenes, but it only works on subjects within the range of the flash, typically 24 metres for a built-in flash. 36

Exposure

Before

After

Using balanced fill flash Outdoor portraits are often difficult to pull off successfully, especially in bright sunlight. If you face your subject towards the sun you reduce the contrast range but you make them squint. If you position them side-one, you get ugly shadows across their face. And if you shoot them with their back to the light, you have the problem that their face is in shadow against a bright background. However, if you set your camera’s flash to forced flash mode, and as long as your subject’s just a metre or so away, it can provide enough ‘fill light’ to even up the tones. You can use fill flash indoors, too, as we have here, to balance up dim indoor lighting against bright daylight outside. If your camera has a ‘slow sync’ mode, you can create interesting flash effects at dusk, too, illuminating nearby objects against a colourful sunset or twilit sky.

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Using a neutral density grad Landscape photographers often struggle with bright skies, particularly on overcast days, where the sky acts, in a sense, as a vast, diffused light source – and one which is 2 EV to 3 EV brighter than the foreground. You have a dilemma. Either you expose for the foreground and risk the sky bleaching out to a featureless white, or you expose for the sky and hope you can drag up enough detail from the dark foreground in your image-editor. If the brightness range is too great (it often is), you need another solution. For this shot, we’ve used a ‘neutral density grad’, a filter which is darker at the top than the bottom. By positioning this carefully in the filter holder, we’ve darkened the sky enough to even up the exposure, but without affecting the foreground. Graduated neutral density filters come in various strengths, which you can match to the brightness range of the scene. It’s largely a matter of personal taste though – do you like the heavily filtered ‘moody’ look, or something more natural? They also come in both soft-edged and hard-edged forms. The softedged sort can intrude intro areas of the frame you don’t want to reduce in brightness (the top of a hill that’s protruding into the sky, say), but the hardedged ones demand even more careful positioning. To get the most from a neutral density grad, you really need a digital SLR, though filter maker Cokin does supply an adaptor kit for digital compacts.

Without Filter

A graduated neutral density filter solves the problem we had with clipped highlights in our landscape shot. It reduces the exposure in the sky area by a factor of 4 (2 EV) to bring it within the sensor’s dynamic range. 38

Exposure

With Filter

Exposure

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Using Photoshop Photoshop CS and Elements 3 have a Shadow/Highlight tool for balancing the tonal values in high-contrast scenes. It works by selecting the darker areas only and then lightening them. The results can look a little artificial if you’re not careful (you need a large Radius setting, which blends the effect more subtly), but they can also improve shots considerably. This will only work, though, if the image contains a full range of tones in the first place. If the shadow or highlight detail has been clipped, there’s no getting it back. For scenes with too high a contrast range for this approach, there is an alternative. You can take two shots at two very different exposure values – one aimed at capturing shadow detail, and one aimed at capturing highlight detail – then blend them in Photoshop. Our walkthrough shows you one way of doing this. (You’ll need to use a tripod to ensure the images align exactly.)

Before

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Exposure

After We needed to reduce the exposure by a massive 6 EV in our second shot, the one being used to record the dusk sky in this beach scene. The blended image records a dynamic range impossible to capture in any other way.

1Combine the shots

The first thing to do is add the lighter exposure to the darker one as a new layer. You can do this by using the Move tool to drag it on to the other image’s window. If you hold down the Shift key as you do it, the image will align automatically.

2Blend the exposures

Now use the Colour Range command and select Highlights from the pop-up menu. You’ll need to make sure the Invert box is checked. Close the dialog box, and click the Add Layer Mask button in the Layers palette. This will mask the bleached-out areas in the top layer.

3Blur the transition

The transition between the two image layers is too abrupt at the moment, but the way to fix that is to blur the layer mask. Making sure the mask is selected in the Layers palette, try a Gaussian Blur of 250 pixels (less for lowerresolution images).

Composition

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Master of exposure Pål Hermansen

L

ike many great photographers of the natural world, Pål Hermansen started his working life doing something else. Born in 1955 in Oslo, Norway, he trained as a dentist and homeopath, but was an enthusiastic photographer from an early age. He decided to turn his hobby into a career in 1971, when he became a freelance photographer and writer. As well producing numerous books, his striking work has earned him international acclaim and many awards. His images stand out from the norm because of their exquisite portrayal of light and creative compositions. He attempts to go beyond documentary -style photographs to create something more artistic, admitting that he perhaps ‘leans more toward the photographic equivalent of poetry’.

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This shot of black-legged kittiwakes, taken on Norway’s Lofoten Islands, proves that sometimes, searching for the ‘perfect’ exposure isn’t always desirable. Would this picture have as much impact if it had a more neutral composition and exposure? Notice how the soft edges of the bird that’s out of focus work in combination with its overexposed white feathers to make it almost glow. It’s an image that provokes extreme reactions – you’ll either love it or hate it.

Intrigued by Pål’s work? See more in the galleries at palhermansen.com. Exposure

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Low light exposures S

hooting at night is easy, it just needs much longer exposures than you’re used to in the daytime. You could increase your camera’s ISO to its maximum and try shooting handheld, but the image quality will drop through the floor, and shutter speeds will still be so long that camera shake is nigh-on inevitable. The best approach is to use a tripod, reduce the ISO to its minimum (to maximise image quality) and experiment. Yes, experiment. While your camera is perfectly happy with the long exposures needed at night, its metering system is likely to be all at sea when faced with the naked light sources and much higher contrast levels after dark.

Exposing in the dark There are two approaches to working out exposures at night. There’s the ‘it ought to be possible to work this out’ approach, and the ‘I give up, let’s just suck it and see approach’. The technical approach would be to take a spot reading from a representative area of the scene like a floodlit building, but excluding any naked light sources. This is time-consuming and error-prone. The simplest route is to start with an exposure of 4 seconds at f/5.6 for a typical city scene, see how it comes out, then reshoot with different settings. There is one thing to beware of, though. Your camera’s LCD will appear much brighter at night, so that while an image may look good when played back at the time, it can prove to be hopelessly underexposed when you get it on to your computer. Instead, use your camera’s histogram display to check the tonal distribution – this is a much better guide.

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Night photography presents special exposure challenges. Often a purely experimental approach is the quickest and best solution.

How to control noise Noise can be more of a problem with night shots, and there are reasons for this. First, if you don’t manually set your camera to a low ISO, it will automatically increase the sensitivity in response to the lower light levels. Auto ISO is a default option with compact cameras especially. Second, long exposures tend to encourage more sensor noise. However, makers now incorporate effective noise-reduction systems that kick in automatically with longer exposures. Check whether your camera does this, or whether you have to enable noise reduction manually. Third, noise tends to be more apparent in darker areas, and night shots can contain large expanses of black or dark tones. You can reduce noise in Photoshop and other image-editors, but only at the cost of some fine image detail. The Dust & Scratches filter is probably the most usable and controllable tool for this.

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High key/low key T

he concept of the ‘ideal’ histogram can be useful when choosing exposure settings and evaluating images, but it’s a mistake to imagine that all images must conform to this even distribution of tones. Intrinsically light subjects, for example, can be expected to produce histograms where the tones are clustered up around the right-hand (highlight) end of the scale, whereas dark subjects should produce histograms shifted towards the darker, left end. This is exactly how these subjects should look. Deliberately light images are called ‘high key’ photos, while dark shots are ‘low key’.

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Exposure

High key

Low key

You can do effective high key and low key portraits using either natural or artificial light.

Going to extremes You can take high key and low key exposures to extremes, and produce striking and creative results. For example, if you place a fair-skinned model against a bright background, and use an exposure which just captures the details of the face at the highlight end of your camera’s dynamic range, the result will have a brilliant, ethereal quality. Or, to produce a far more sombre, dramatic portrait, you need to choose a dark background, contrasty lighting, and set an exposure that records the highlights on the subject’s face but the shadowed side and the background as very dark, near-black tones. The histograms for these images will be very far from the ‘ideal’ shape, and may also have clipped highlight or shadow detail. Nevertheless, they can work very well as photographs. The point about histograms is that they simply tell you what the image is like – they’re a diagnostic tool. They’re not there to tell you what the image ought to be like. That’s your job as the photographer.

Exposure

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Master

Exposure

Top 10 tips...

TAKE A MID-TONE WITH YOU Pack a grey card in your camera bag – or buy a mid-toned camera bag which you can meter off.

1 2 3 4 5

RESTORE THE WHITENESS If your subject’s large in the frame and bright white, spot meter off them and add 2 EV to 2.5 EV.

6 7 8 9 10

LOOK AT THE HISTOGRAM Don’t rely on a simple playback image to judge exposure – let the camera show you precisely…

METER FOR HIGHLIGHTS As a general rule, it’s best to meter for the highlights and let the shadows fall where they will.

WATCH THE BACKGROUND Be aware of how the tone of a background can influence your camera’s meter.

CARRY A SET OF FILTERS Always pack a graduated neutral density filter and polariser – they’re not just useful for ‘pure’ landscapes…

BE AWARE OF HIGHLIGHTS When exposing for dark subjects, look for any bright areas that might be blown out as a result.

DIAL DOWN YOUR FILL FLASH With digital cameras so good at picking up shadow detail, you’ll be surprised how little fill flash you need.

SWITCH TO SPOT METERING For tricky lighting and small areas, there’s no substitute for spot metering if you’re not in a rush.

GET CREATIVE Don’t always chase the ‘perfect’ exposure. Experiment with going to extremes.

Exposure

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