Work out light meter reading instantly with clear inputs, formula shown and shareable results.
The metered EV is shifted for ISO, then the aperture follows from rearranging EV = log2(N squared over t) to give N as the square root of 2^EV times the shutter time. Working from a metered EV rather than the camera's own suggestion is what lets you fix shutter speed for motion and let the aperture fall where it must.
EV at working ISO
EV = EV at ISO 100 + log2(ISO / 100)
Aperture
f-number = sqrt(2^EV x shutter time)
EV = EV at ISO 100 + log2(ISO / 100). The metered EV is shifted for ISO, then the aperture follows from rearranging EV = log2(N squared over t) to give N as the square root of 2^EV times the shutter time.
Working from a metered EV rather than the camera's own suggestion is what lets you fix shutter speed for motion and let the aperture fall where it must.
Enter metered exposure value at iso 100, iso you are shooting, shutter speed you want. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.