The light meters in digital cameras grow more sophisticated and ‘intelligent’ every year… but our cameras still give us exposure errors and inconsistencies. So why is this, and can the meters built into digital cameras every be truly foolproof? Maybe not. Here are nine things you may not have realised about your camera’s metering system, its limitations and how to get the best from it.
01. Your camera can’t tell black from white
It’s true. The camera can’t tell a black cat from a white wedding dress.
It can’t recognise objects with different intrinsic tones in the way we can, and all it can do is measure the amount of light reflected by the subject and adjust the exposure so that it comes out an average grey tone.
To make sure a black cat really does come out black, you have to add a manual exposure reduction with the EV compensation control.
And to make sure a white object comes out a true white, and not a muddy mid-grey colour, you have to manually increase the exposure over what the camera recommends.
02. Matrix and evaluative metering are educated guesswork
Multi-segment ‘matrix’ or ‘evaluative’ metering systems break the scene down into many different areas and analyses the distribution of light to try to work out what kind of subject you’re photographing by checking this against a database of ‘typical’ subjects in their memory banks.
It’s clever and sophisticated, and the camera is trying to guess how you want the picture to come out, but it is only a guess.
For example, if you take a picture of someone with the light coming from behind them, the camera may think you’re shooting a backlit portrait where you want their faces correctly exposed, but you may actually have wanted a silhouette.
That’s why you sometimes have to take control of the exposure yourself.