Ex-po-sure /ɪkˈspoʊʒər/ [ik-spoh-zher] -noun

1. the act of presenting a photosensitive surface to rays of light.
2. the total amount of light received by a photosensitive surface or an area of such a surface, expressed as the product of the degree of illumination and the period of illumination.
3. the image resulting from the effects of light rays on a photosensitive surface.

While the definition of exposure tells us what it is, it tells us nothing about what a correct exposure is or how to go about achieving it. For better or for worse, only you can decide what the correct exposure is in each situation. A photograph that is all white (over exposed) or all black (under exposed) is certainly a “wrong” exposure, but just about anything in between can be a correct depending on your personal, artistic choice. Examine the following 3 pictures of the same object:

Image credit: Imroy.

Most people would choose the middle frame as the correct exposure, but all three are equally “correct”. The left-hand frame could be a low-key picture, while the right-hand frame could be high-key; it all depends on what you’re after.

It is impossible to capture a scene on film or CCD that exactly reflects what our eyes are seeing (this will be the subject of a future post, but in the meantime you might want to read this or this). The reason is that the human eye can perceive a larger tonal range than film or CCDs can. To put it simply for now, a light of any colour, say red, that is bright enough to appear pure white on a CCD (because it is saturating it) can still appear red to the human eye; it will need to get much brighter before we start to see it white. At the opposite end of the scale, the opposite is also true; in shadow areas that appear black to a CCD, the human eye might still be able to see details and will require that area to be a lot darker before we start to see it black and featureless.

Given this impossibility then, we need to decide what tonal range of the scene we want to capture. That is, we have to decide whether we want to see stuff in the shadows and let the bright parts be washed out, or see detail in the bright parts and have the shadows be dark and mostly featureless. Most cameras nowadays will decide this for you and try to take the middle road. Sometimes this is a good thing, but I feel that whenever you let your camera do the thinking for you, you are giving up your artistic freedom.

Choosing the exposure will be your first step toward taking control of your photography, and you will find that it plays an important role in making a photograph. Control is the key here: You have to decide what the photograph will look like, and do it before you take it. Don’t worry, it’s a lot easier than you think, and in part 2 of this article I’ll be explaining to you how you can do it.

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Related posts:

1. Achieve the Exposure You Want, Part 2
2. The Basics of Camera Exposure Controls
3. Beautiful Photographs Made with a Long Exposure Lens
4. Inspiration. I Have a Camera, What Next? Part 2
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