Flash compensation is a feature that can be found on some digital cameras that allows you to control the power of the camera's flash unit (check here for more details).
When using a fill flash (check this) to lighten up a dark foreground subject compared to a bright background, flash compensation may be of utter importance.
Below are two photos I have taken of a subject placed in a relatively bright background.
I was using a Nikon D60 with the following settings kept the same across the two shots:
- focal length: 135 mm
- f-stop: 6
- shutter speed: 1/80 sec
- 400 ISO, Matrix metering, auto WB
I also used fill flash. Should I have not used fill flash, the foreground subject would have come out way too dark.
In figure 1 I did not use any flash compensation. Notice how some areas of the subject are washed out (overexposed): bottom right corner of each box and the center spot of the blue box.
Figure 2 was taken with a flash compensation of -1.3 EV. Notice how the washed out areas have diminished.
I hope this proves useful.
figure 1: fill flash with 0.0 flash compensation.
figure 2: fill flash with -1.3 flash compensation.
