Multi-segment metering mode. This mode also associates itself to a focus point and assumes that the area in focus is the subject. It then applies a set of rules to try and correctly expose the subject. However, if your subject lighting does not match the design criteria of the metering system you are still in trouble.
So early meter reading systems assumed that the reflected light from the subject is 18% of the incident light. This is because scientist measured that value from a typical landscape scene. A Gray Card is designed to reflect this value so they are useful to take reading from in tricky lighting conditions.
However, whenever you step outside of the typical normal scene you have to make a judgement on how best to get a good exposure. Then with experience it becomes intuitive as outlined in Duncan's examples.
Remember also many of the DSLR cameras have a histogram feature with the image preview. Ideal if you are able to take a number of shots to get the exposure correct.
Rob
Last edited by robski; 03-01-06 at 13:21.
|