Photography Exposure Calculator
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Formula
EV (at ISO 100) = log2(f-number^2 / shutter speed in seconds). Adjusted EV = EV100 - log2(ISO/100). EV 15 = bright sun, EV 10 = overcast, EV 5 = indoor, EV 0 = very dim.
Frequently Asked Questions
What is Exposure Value (EV)?
EV is a single number that represents a combination of aperture and shutter speed. Higher EV values correspond to brighter conditions. EV 0 is defined as f/1 at 1 second at ISO 100.
How do I use the exposure triangle?
The exposure triangle is ISO, aperture, and shutter speed. Changing one setting requires adjusting another to maintain the same exposure. For example, doubling ISO allows you to halve the shutter speed or close the aperture by one stop.