Exposure Compensation

skai

What is exposure compensation and how is it used?

ohyeahar

The 3 things that affect exposure in photography are aperture, shutter speed, and ISO. Each of these have a direct effect on how much light the sensor picks up. By balancing out these 3 things, you get an optimal exposure where it’s bright enough to see but dark enough to maintain contrast and details. If a photo is over-exposed, that means it’s too bright; details are washed out in the light. If a photo is under-exposed, that means it’s too dark.

If you utilize your camera’s light-meter to automatically set the aperture, shutter speed, or ISO, the camera will always try to maintain what it thinks is the optimal exposure. But there are instances where you may want to over or under expose, so you do that via exposure compensation.

A couple of examples of when it may be a good idea to use exposure compensation:

1) You’re photographing a bride and groom. Because the bride’s dress is white, it’s likely that your camera has over-exposed it so it'll lose all the details. You won’t be able to see the stitches and beads, etc. It’s all washed out in white because it’s too bright. What you need to do here is under-expose a bit to bring out the contrast of the dress.

2) You’re photographing an indoors concert. You’re already shooting at your lens’ maximum aperture and ISO is already at 1600 which you’ve decided is your limit. The lighting is poor so the camera is selecting a slow shutter speed which is not fast enough to freeze the action. What you can do here is to under-expose a bit to boost the shutter speed. You’ll end up with very dark shots but at least you’ve frozen the action. Assuming you’ve shot in RAW, you can easily boost the exposure back up in post.

3) You’re photographing someone who’s backlit by the sun. Because of the overwhelming light source, the subject is too dark and appears as just a silhouette. If you want to see the details of your subject (i.e., face, clothing, etc), you’ll need to over-expose a bit.

4) You’re photographing something where there’s snow in the background. Since snow is white, the camera thinks it’s a huge light source. It’s likely that your subject will be under-exposed against the snow, similar to the backlit case in #3, so you’ll need to over-expose a bit.

PBked

Hi,
Very clear descriptions from @ohyeahar as usual. Here is my tuppence worth. Let's say you have taken an exposure reading from the camera and it suggests f/3.5 which is as wide as the lens you are using will open, but your picture is a little dark. By dialing in 1 full stop of exposure compensation you are fooling your camera into thinking it actually has a lens that will go to f/2.5 wide open. However, beware because the -3 - 0 - +3 numbers on the exposure compensation indicator are usually defaulted to 1/3 of a stop increments. So to achieve 1 full stop you would have to dial in +3. I believe on the 60D you can change the increments to 1/2 stop using the custom function menu number 1. Just checked and you will find it explained on page 252 of your manual.
Happy shooting,
PBked