Properly exposed background, dark subject

Do your photos sometimes look like this?

There must be something wrong with your camera right? You were trying to take a nice photo in front of a sunlit scene and for some reason the background looked great, but the people are just way too dark. What happened? They didn’t look this way in real life. Perhaps they’re unlucky. Perhaps they walk around with a preverbal “dark cloud” above their head which always puts them in a shadow.

NO that’s not it, but how cool would that be to have your own cloud follow you around? The reason the people in your photo are dark silhouettes is because your camera did not pick the right exposure for that scene. First a little background(no pun intended)…

Just before snapping a photo your camera employs many many sensors to create the finished photo, including an exposure sensor. This sensor measures all of the light in the scene and computes an average amount of light in the scene you are about the photograph. Oh there’s one more thing you should know about most exposure sensors it has a bit of a handicap, it can only see in black and white.

Aww the poor thing…I know it’s a sad story, but that’s ok because the exposure sensor has learned to deal with it’s disability and it excels at picking the proper exposure for your scene, most of the time. You see the exposure sensor is programmed so that everything it sees in the photo will look like a middle gray.

Now what’s a middle gray, well it’s a gray that isn’t too white, or too black, it’s sort of in the middle Actually in terms of numbers middle gray for digital cameras is about 18% gray. It’s different for film. So when your camera’s exposure sensor averages all of the light coming into your scene it compares it to middle gray. Middle gray is your camera’s “happy place”. Your camera would love all photos to average out to middle gray.

In fact, that’s what it tries to do. When the average light in your scene is compared to middle gray the camera will choose an exposure that comes as close as possible to making the average light in your photo register as middle gray. This works very well in most situations. Plus several newer digital cameras have pre-defined exposure templates built-in which help your camera to nail the exposure correctly more times than not.

So then how did your people in front of the sun turn out to be dark silhouettes? Well when your camera “metered” the light in your scene it detected many bright areas, this is because you were shooting towards the sun. So imagine the photo as your exposure sensor sees it, in black and white. From the cameras point-of-view it is on average a very brightly lit scene. So the camera does what it’s programmed to do and compares this very bright scene to middle gray.

As you can see from the photo above, the few people in your scene are very dark compared to the rest of the brightly lit scene. So when the average light in the scene is compared to middle gray the camera says “the average light in this scene is much much brighter than middle gray, so I need to choose an exposure value which will darken the scene.” Hence, you get a lovely exposed sky and background, but dark silhouetted people.

A great choice if you were taking a photo of the bright background. However, you wanted the camera to set it’s exposure for those people in the scene, not the big bright background. So what can we do about it? Well your camera realizing that it’s only right about 80% has a feature that will allow you to fix this problem when taking your photo. Allow me to introduce….Exposure Compensation!

Almost all digital cameras and film cameras have an exposure compensation feature, sometimes known as “backlight compensation”. Just look for the universal symbol for exposure compensation . Exposure compensation allows you to adjust the camera’s exposure to suit your scene. In our case where our people are silhouetted we would increase the exposure by +1 or so which would properly expose for the people in the scene, but the background would tend to be a bit overexposed. This is acceptable since our main subjects are the people and not the background.

I know you guys though…you’re saying “Scott, why can’t I just move my subjects so that the sun is in front of them and not behind them, wouldn’t that work too?” Of course it would, but there are many times when exposure compensation needs to be employed, not just when the sun is behind your subject. How about taking photos of your kids in the snow? All of that white snow everywhere reflecting into your camera’s lens will cause the exposure sensor to underexpose your subjects just as if it was in bright sunlight. So we can employ exposure compensation to expose those kids properly.

Exposure compensation isn’t only for bright scenes, it works the other way as well.

What if you have a friend who enjoys boating on a lake, it can get pretty dark on there, especially towards the end of the day. Say you take a picture of him or her.

Here we have your friend against a dark blue lake background. When your cameras exposure sensor meters the light it’s going to average out as a very dark scene, much darker than middle gray. So what’s going to happen?

Your camera is going to choose an exposure that makes the whole scene brighter. This is fine if you’re goal is to shoot the lake, but you’re trying to shoot your friend, who is now very overexposed and washed out.

So what do we do to fix this? Drain the water and shoot them on sand!!! No, not quite, we can employ exposure compensation to fix our exposure but this time in the negative direction. Maybe -1. Now our friend is properly exposed. However, the lake is a bit dark now, this is acceptable though because your friend is the main subject of the scene.

So the next time you find your cameras exposure sensor is not seeing things as you see them, employ some exposure compensation and make your camera expose the scene as you want it to!

Feel free to leave comments and post some of your results.