Fortunately, there’s a simple way to correct this by switching your metering to centre-weighted. This will mean that greater emphasis is put on exposing the centre of the image correctly. With many DSLRs there’s also the option to link your active AF point to the spot metering area. This means that you can still correctly expose your subject, even if they’re not in the centre. However, you do need to remember that spot metering only meters for the centre 5% of the image.
3. Greying whites
Modern DSLRs come with incredibly sophisticated metering systems, which can, most of the time, produce perfectly exposed shots. However, a large area of a light colour, such as white, can cause the camera great confusion. This is due to several factors. Firstly, the camera has some trouble actually seeing white in the first place. And secondly, but more importantly, camera-metering systems look for averages in a photo.
So, whilst a camera will expect there to be areas of bright and dark in the photo, they’ll expect that these will average out as a midtone. The problem is that if you fill the frame with a light subject, the camera will then reduce the exposure in order to create that midtone – thus turning the white grey.
Fortunately, this is very simple to correct by just dialling in some exposure compensation. This will set your exposure above the value suggested by the camera. The amount of +EV needed will depend on how much white there is in the photo, so be prepared to experiment a little.