In order to perfect your metering you need to see through the eyes of the meter. Perfect exposure is easy: it’s a combination of the right shutter speed and lens aperture for any given scene. But as we all know and have pictures to testify, arriving at that combination is not quite as simple. Your camera is equipped with sophisticated technology to help you figure out each lighting condition. But you must understand how the meter views the world. When you look through the camera, your eye and the film both record approximately the same scene. Not so for the half-blind meter.
As a kid, did you ever wonder what it looked like through the eyes of your cat or dog, or even a fly? Well, if you’re curious about what your light meter sees, take the lens off your camera and look through it. That’s about all the light meter can see. So when you look through the camera and see delicate plays of light bouncing off your subject’s profile, remember all the meter sees is a slab of gray. You have to program the fine-tuned data yourself.
The next chip of information we need to feed into your gray matter is the notion surrounding the 18 percent gray card. All light meters and films are calibrated according to this standard gray. Light meters are brainwashed into believing that the entire world is nothing but a big, gray mass. They are taught that all things look average gray and if they spot anything lighter or darker something is dreadfully wrong and their controls must be adjusted until the scene looks gray again. If there is extra white in the frame, the meter will call for less exposure to return the white values back to gray. If darkness overrides the scene, the meter quickly determines that extra exposure will lighten the scene enough to gray it up again.
Therefore if you focused your camera on a piece of gray paper and followed your light meter reading you would always get a perfect exposure. Or if you filled half your frame with a white card and the other half with a black card, again you would have perfect balance and your meter would have no complaints. The problem is that few scenes are in such balance.
What would happen if you took a picture of a pure white card? Your meter would look at it and say, “Let’s make this thing gray,” and underexpose enough until the white actually looked gray. If you did the same thing with a piece of black paper, your meter would compensate again, and you’d still get a gray picture. If you want solid white or black to show as white and black in your picture, you have to manipulate your meter. Since most scenes are not balanced perfectly, understanding this principle will help you fine-tune your exposures to achieve better results.