In part two
of this three-part series about the importance of light Robert Keeley explains
how colour temperature can impact on images, and how to use natural light to
the measurement of light and its colour temperature have a huge impact on how
you can create an image, and they can be quite technical to explain, but there
are some basic tenets involved for which it’s worth gaining a basic
understanding. This week we’ll look at how colour temperature affects the
creation of your images, and then outline some useful approaches you can use
when shooting in natural light.
temperature is an involved subject, but having some knowledge of it allows you
to assume greater control over the 'look' of your images. In as much as it’s
possible to be brief, here are a few key points worth noting. In the days of
film, different emulsions were prepared for specific light conditions, but with
digital cameras, especially SLRs, photographers now have the option of changing
their camera's 'white balance’ setting to more closely match the conditions
they are shooting in. This can be handy if you know what the colour temperature
is of the scene you’re trying to photograph - or it can be headache if you
Late afternoon light can be highly effective. Rays of light cut through the atmosphere at an oblique angle, offering a warm tone to the scene.
The same scene taken earlier in the afternoon has less colour in it, as the sun's rays are cutting through the atmosphere at a much more direct angle. Thus the time when you shoot outdoor images becomes critical.
Generally, the safe option when you’re not sure is ‘Auto White Balance', which all modern cameras offer. But changing your white balance setting can be a creative decision. Colour temperature is a method of describing the colour of a black body as it is heated up (sometimes described to as a metal object heated in a furnace). As it heats up the black body assumes different colours and thus different temperatures. 'Kelvin' (formerly known as 'degrees Kelvin') is a scale used for measuring temperature. At lower temperatures the black body will glow red, then yellow, and finally as it heats up, white. As it gets hotter still it will turn blue. The 'warm' (red/yellow) colours measure around 2700–3000K (kelvin), while over 5500K will produce a 'cooler' white to blue light. For example, a match flame will measure around 1700K, an incandescent light bulb 2700-3300K, white fluorescent light around 4000K, overhead daylight approximately 5200K, cloudy conditions around 7000K, with twilight and beyond over 9000K.
An extreme example of midday light, and the impact it can have on your image. With this harsh light, you aim to expose correctly for the highlights in the scene. Afterwards, with post-production software, you can pull out details from the shadow areas of the scene, unless you wish to use the dark areas as part of your composition.
The colour of the sun will vary throughout the day, but this will mainly occur due to the scattering of light as the sun's rays change their angle of trajectory through the atmosphere. While Kelvin is a measurement of controlled lighting, most lighting in the outside world isn’t under controlled conditions, so the colour temperature can vary, but your camera can usually be set in its ‘White Balance’ mode to match the type of light you’re facing (and the menus on SLRs will often describe the various White Balance conditions), or to ‘Auto’.
For creative purposes, however, you can change the white balance of your camera and create different effects, deliberately moving it off the so-called 'correct' setting to give a certain mood to a particular scene. You can deliberately create a bluish 'cooler' feel or an orange/yellow 'warmer' ambience to an image. Basically, if you want a 'neutral' appearance to whatever light you're shooting in, set your white balance to match the conditions. Because the menus in most SLRs will offer some descriptive help as well as a temperature reading in Kelvin it's relatively easy to match or change your white balance setting, but leaving it on 'Auto' or AWB is a relatively safe option. It costs you nothing to experiment with white balance so when you're shooting an image, shoot in the so-called ‘correct’ mode, then try changing it and note it’s impact.
USING THE LIGHT
Light is the basis of all photography – without it you can’t make a photograph. But if you don’t know how to control it, or use it to maximum effect, light can ruin your photos.
incumbent upon every photographer trying to improve their image-making ability
to learn how to manipulate light more effectively. We have looked at how a
camera measures light via its metering system, and the impact of the colour
temperature of light, and how it can be controlled through the use of 'white
balance' mode. These are relatively technical issues and though they're
important to understand, it’s also critical that photographers develop their
own 'feel' for what the light is doing.
When the sky is overcast the effect is to soften the light. You can use this to capture details which may disappear in a wider range of contrast when the light is stronger.
The same scene shot in much stronger light creates an image where shadows become much more important to the composition. You need to educate your eye to 'see' this difference, which can be difficult to pick up as your eyes cope with a much wider range of contrast than most digital sensors.
You need to educate your eye to see in photographic terms. Because our eyes cope with a much wider range of shadows and highlights than most digital camera sensors, the image we want to photograph may not come out as we have seen it. You need to really study the impact of light on outdoor (or even indoor) scenes. Note when the light is creating a 'warm' ambience (say just after sunrise or late in the afternoon) or a 'cool' feeling (just before sunrise or just after sunset, or on cloudy, gloomy days). In the middle hours of a sunny day, study where and when harsh, dark shadows occur. Because the dynamic range of most current digital camera sensors is more limited than our eyes, they simply won’t record all the details we can see in such a scene. Either the shadows will remain dark blobs, or the bright spots will become blown-out highlights.
With digital cameras in these circumstances it's better to shoot to record the detail in the highlights and leave the shadows dark. Then with software or using High Dynamic Range technique you can recover the detail in the shadows later, or leave it alone if it's part of your creative style. But detail lost in blown-out highlights can never be recovered. (It should be noted that your chances of recovering details in shadow and highlight areas improve if you shoot in RAW mode rather than JPEG, and many DSLRs offer the option of shooting in both modes simultaneously.)
understanding the impact of light on your images is so important, it's worth
setting up an exercise to educate yourself. Find a particular outdoor location
that's convenient to you. It may be in your backyard, on your local street, in
a park, or near where you work. Then make a point of studying that spot
throughout a day. Note what the light is doing early in the morning, then
through to the midday hours, then late in the afternoon, and finally in the
twilight hour after the sun has set. If street lights or neon signs light up
after dark, see what impact they have on your scene as well.
Repeat this exercise for a week, then periodically over a few months. Note how your scene is affected on dull, cloudy days, and on bright days. See what impact any rain may have, and note the effect of changing seasons. Pay particular attention as to how the angle of the sun throughout the day impacts on the scene. Don’t take photos, don’t think about your camera. This is simply an exercise to educate your eyes.
a few weeks, try photographing the scene with a view simply to recording the
impact of light, bearing in mind all we've discussed. You will most likely note
how the angle of the sun through the day can dramatically change how your scene
looks at certain points during the day. When the sun’s rays cut a low angle
through the atmosphere at the beginning and towards the end of each day, your
scene will have a warm ambience. When a bright sun is shining through the
middle hours of the day the shadows will be harsh.
Take a photo several times during one day – once early in the morning, once around mid-morning, then at midday, mid-afternoon, around late afternoon, at sunset, and once in twilight. Then undertake the same shooting regime on a day with different weather conditions. You'll probably find that if it's just rained your images will be crisper – because the atmosphere has been cleared of grit and dust, which in turn affects how you will see the effects of light. If you've undertaken the exercise properly, these seven images should give you a much better understanding of the impact of light on the scene, the effect of shadows, and how the hour of the day can change the overall ambience dramatically. You can compare the same scene simply on the basis of the impact of light.
You'll find that morning light will create a warm ambience, midday light (if it’s not cloudy) will create harsh shadows, later afternoon light may well be warmer, and post-sunset conditions will probably be 'cooler'.
Early morning and late afternoon light are often excellent times to shoot landscape images because of the warm ambience of the light. If your scene has other atmospheric effects, like fog (seen here) or stormy conditions, you can create a scene with tremendous impact.
Remember, if you’re serious about outdoor photography you should carry your camera with you as often as possible, especially when the weather is about to change. You never know when such a change will produce dramatic lighting conditions worth photographing.
For the final part of this series, where we look at special
lighting situations, including how to use 'window light' and night shooting, click here.
To look back at part one of this series click here.