(Another post from the old (defunct) photos.stormi.ca site.)

In 1939/40 Ansel Adams along with Fred Archer, developed something called the Zone System. Your camera’s meter is based on it.

Why is this important to me, you ask? The reason you want to learn about this, only a little, is so that you can understand how your camera’s meter works.

What you see at the top and the bottom of this post, is a a representation of the Zone System.What you need to remember, is when your camera meters, it tries to make everything in the area that it’s metering represent as Zone V on the scale. This represents 18% gray.

What this means to you is when you take a picture of a snowy landscape, if you don’t correct for your camera’s meter, you will end up with grey ( or if you’re shooting in color, light blue ) snow. Or,… if you try to take a picture of a very dark subject, a black car for example, your picture will be of a gray car. This is because of the way that your meter works. It is trying to “normalize” everything to Zone V.

The reason that this happens is when your camera’s meter “sees” the snowy scene, it goes “Holy COW That’s a LOT of light!” So it closes the shutter more. It’s sort of like when you go outside into the bright sunlight, and your pupils contract to compensate for the light. Your camera will do something similar.

So, how do you compensate for this?

If you’re taking a picture of a very bright subject, (let’s use our snow example again) you would do the following:

If you have an adjustable ( or manual ) camera, you can compensate for this in 2 ways.

1. Open up your shutter 2 stops ( For example: Up to F2.8 from F11), or slow your shutter speed down by two stops (For example: 1/250th to 1/60th of a sec. The effect will be the same. You’re trying to let more light into the lens than your meter thinks that it should.

2. Meter on something that represents 18% gray. This could be grass, or asphalt, etc. Once you’ve metered on this, recompose your picture of the bright subject with the settings you gathered from the grass, etc. In the absence of something that’s 18% gray, you can meter on your hand, and open up one stop.

If your camera is fully automatic ( like a point and shoot camera. ) Your only option is to meter on something that represents 18% gray.

If you are taking a picture of a dark subject, the black car for example, you would close the shutter more, or speed up your shutter speed to compensate.