what is an ev
meV, keV, MeV, GeV, TeV and PeV redirect here. For other uses, see MEV, KEV, GEV, TEV and PEV. In physics, the electronvolt (symbol eV, also written electron volt) is a unit of energy equal to approximately 160 zeptojoules (10â21 joules, symbol zJ) or 6981160000000000000â 1.6Ã10â19 joules (symbol J).
One stop is a factor of 2 (2x or 1/2). One EV is a step of one stops compensation value (could be aperture, shutter speed, or ISO, or some combination). This +1 EV means a one stop greater exposure. I assume this basic compensation use is already known. The rest of the page is about the absolute EV numbers.