What other aperture, shutter and ISO settings give the same exposure?
Enter an aperture, shutter speed and ISO to see the exposure value (EV) and a table of settings that give the same brightness. You can also say which setting you changed and see how to compensate.
How the tool works
Exposure value combines aperture and shutter speed into one number: EV = log2(N squared / t), where N is the f-number and t is the shutter time in seconds. To compare scenes at different sensitivities, the tool reports EV100, which subtracts log2(ISO / 100). For example, f/8 at 1/125 s and ISO 100 gives EV100 12.97, about an overcast sky. Each whole number of EV is one stop, so a change of one stop doubles or halves the light.
Equivalent exposures keep the same total light. Opening the aperture by one stop lets you halve the exposure time or halve the ISO. The table keeps your ISO and steps the aperture through full stops, showing the shutter speed that matches. Pick the pair that suits the picture: a wide aperture for a shallow depth of field, a slow shutter to blur water or clouds, a low ISO for the cleanest file.
The calculation uses exact aperture steps (f/5.6 is really f/5.66) and the marked shutter speeds, so results can differ from a camera meter by a few hundredths of a stop. The light descriptions are a rough guide only. The Sunny 16 helper gives a starting exposure without a meter, so check the histogram and adjust.
Questions
What is EV100?
EV100 is the exposure value for ISO 100. It describes how bright the scene is regardless of the ISO you used, so settings from different cameras and ISO values can be compared on one scale.
How do I keep the same exposure when I change the aperture?
Change the shutter speed by the same number of stops in the opposite direction. Closing the aperture by one stop, for example f/8 to f/11, needs a shutter twice as long, such as 1/125 s to 1/60 s.
What is the Sunny 16 rule?
In bright sun with distinct shadows, set the aperture to f/16 and the shutter speed to about 1 / ISO. Open the aperture one stop for each step down in light, from slight overcast at f/11 to open shade at f/4.
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