Of all the thousands of pounds that can be spent on hi-tech photographic gadgetry, who would think that a simple piece of grey card could be such a useful, if not essential, item for a professional photographer to possess.
As complex as Digital SLRs are today they do not have eyes and a brain like us humans, they are still unable to instantly recognise what they are looking at. They need to be programmed to provide a correct exposure for any lighting conditions and subject matter that reflects this light in different ways. So, a “standard reference” is required and that is an 18% shade of grey. What this means is that the camera assumes that the average amount of light reflected from the scene you observe in the viewfinder is the same as if the scene was filled with 18% grey. This then gives us the ISO, shutter speed and aperture setting for a correct exposure.
Thus, one of the best tools a photographer can have in his kit bag is a Grey Card. It is, literally, just a plain grey card that can be used for the camera to obtain a consistent exposure reading in, what could be, difficult lighting conditions. Easy to use, just place the card in the scene at the focal point and angled toward the main light source. Fill the frame with the grey card and take a meter reading from the camera. This should then give you a correct exposure for the shot.
Of course, a Digital Light Meter will do exactly the same thing and more but these cost hundreds of pounds. Fine if you have the money but I’ll stick with my Lastolite Ezybalance Grey/White card for the time being which can also act as a small reflector.