Exposure Exposed

August-September 2002

This is an article from WaveLength Magazine, available in print in North America and globally on the web.
To download a pdf copy of the magazine click here: > DOWNLOAD

by Jacqueline Windh

Underexposing this photo by one stop relative to the metered reading made the bear come out a pure, rich black rather than washed-out grey, and also kept the rocks in the background from being too bright and distracting.

Do you find yourself returning from kayak trips with vivid and colourful memories, only to be disappointed when your films come back drab and washed out? Well don't despair, and definitely don't give up.

The word 'photography' means, literally, 'painting with light'. On the water, there is a lot of light and it is often coming from many directions. Painting with light is tricky here.

In my learning journey as a photographer, I have found exposure to be the hardest element of photography to learn to handle well. Composition is somewhat instinctive, and most cameras do a good job at focussing for you if you wish. But getting the right exposure is something that even the most advanced cameras cannot do for us in a fail-safe way. Handling exposure requires some sort of knowledge of how the camera tries to think for us, and how sometimes we must outsmart it.

First of all, what is exposure? Many people think it is the same as shutter speed. However, on most cameras (except for those set on a fully manual setting), when you change your shutter speed, the camera automatically adjusts the aperture so that the exposure actually remains the same. You open the shutter for twice as long, and it compensates by making the hole (aperture) half as big, so the same amount of light gets in. By fiddling with the shutter speed, you have not actually changed your exposure!

As I took this photo, I was aware that the bow of my kayak made a large area of white, and that I was shooting into the sun, as can be seen by the light reflecting off the water near the centre of the photo. Shooting on automatic would have resulted in a grey kayak bow and very dark shoreline. To compensate for all of the brightness, I overexposed the photo by one stop relative to the metered reading. (Sydney Harbour, Australia).

Why would you want to change the exposure? Most modern cameras have a built-in light meter. They assume that you don't want your picture to be all black or all white - you want it somewhere around grey. And for most pictures, that is fine. But if you suddenly find yourself face-to-face with a black bear, you don't want your picture to be grey, you want it to be black! You need to find a way to fool your camera into letting you take the picture darker than what its meter is suggesting.

Likewise, if you are paddling on an overcast day, and the sky and the reflecting water are both bright white, and you want to take a picture of your buddy, your camera will try to make the picture pretty much grey - the white sky and water turn grey, and your buddy turns into a silhouette. How many of us have pictures like that in our albums? We need to be able to look at a scene, and decide whether, in black and white, it would be mostly grey (in which case the metered reading is probably fine), or whether it has large areas that are either very dark or very bright, and requires an adjustment in the exposure.

Now, how to make that adjustment? If you have a very basic point and shoot, you might not be able to. The only thing you can do is adjust the framing to even out the exposure - back off from the bear (which might be a good idea anyway) so that she doesn't fill the frame. The rocks around her will be the 'grey' and your bear will come out black. Zoom in on your buddy so you cut out all of that white sky and water, and his colours should come out bright and true.

Sunsets are tricky - choosing the exposure depends upon how much black areas there are in the photo, or if it is purely sky and water. If there are significant black areas, like the water in the lower third of this photo, I usually underexpose by about one stop relative to the metered reading.

If you do have the ability to control the settings on your camera, you can adjust the exposure in one of two ways. Some cameras have an exposure over-ride button where you can keep the camera essentially on automatic, but you can adjust the exposure by a number of 'stops'. One stop is equivalent to doubling or halving the amount of light that gets in.

On other cameras you must read what the recommended reading is, then dial in your new reading manually - either changing the shutter speed or the f-stop (but not both!). For example if you are shooting at 1/125 of a second on aperture f8, you can go up or down one exposure stop by keeping the f-stop the same, and going up to 1/60 second (overexposing) or down to 1/250 second (underexposing). Alternatively, you could keep the shutter speed constant, and increase or decrease the f-stop.

A final way to trick some cameras is to adjust the ISO (film speed) setting. For example, if you have 200 film in a camera that does not allow you to adjust for exposure, if you can set it as if it were 100 film, it will lighten the photograph by one stop. If you set it to 400, it will darken it by one stop. (Don't forget to set it back to 200 after that photo). Unfortunately, many new cameras automatically read the ISO of the film and do not allow you to 'fool' them.

For reference, the progression of 'stops' are:

• by shutter speed: 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/ 1000 (faster shutter speeds give darker pictures)

• by f-stop: 2, 2.8, 4, 5.6, 8, 11, 16, 22 (higher numbers give darker pictures)

• by film speed: 25, 50, 100, 200, 400, 800 (dialing in higher numbers than the film you are using gives darker pictures).

Remember, adjusting one of these (e.g. shutter speed) will only change your exposure if you keep the other two constant. In general, if I am shooting in snow or into bright sunlight I overexpose by 1 to 2 stops. If I am shooting dark green forest scenes I underexpose by a half to one stop, and if I am shooting black bears up close I underexpose by 1 to 2 stops.

Exposure is probably the hardest aspect of photography to learn, and it is something your camera cannot do for you. If you are really committed to learning it and getting it right, try 'bracketing' some special photos - when you are dealing with a tricky lighting situation, click off a few frames at different exposures, and write down what you did! You will find after time that the process becomes more instinctive and that your success rate improves. Have fun, and happy shooting!

© Text and photos by Jacqueline Windh, PhD. Jackie is a professional photographer living in Tofino, BC. See: www.portfolios.com/photog/18084.windh/index.html Also check out her new wolf website: wildwolvesbc.tripod.com