Flash output level compensation
From The Glossary of Digital Photography
Also called flash exposure compensation. A feature of auto TTL-type flashes to allow the amount of flash to be increased or decreased over what the automatic flash calculates. Flash exposure compensation is especially useful in digital photography where the results of a test photograph can be seen to be over- or under- exposed, which can be caused by the amount of light or dark in the background, for example. See also flash exposure compensation
