How To Use The Sunny 16 Calculator

This tool is designed to quickly calculate exposure settings for your film camera - based only on the ISO of your film and the weather conditions 🫶🏼

It will not replace an accurate light-meter reading (either in-camera or via external device) but it is much faster to use on the go!

Please note that the tool is limited to shutter speeds 1/8000s and slower. If it recommends a speed that fast - for example in bright sunshine with ISO 3200 and your aperture open at f/1.4 - then be aware that your film may still be over-exposed. To be honest this is unlikely to be an issue - I don't know many film cameras that can shoot even as fast as 1/8000!

The tool also uses the most common shutter speeds and aperture sizes - it may be that your camera is able to access different settings. As long as they're close (for example 1/100s vs 1/125s) then your film will still be well exposed.

 

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Why Is It Called The Sunny 16 Calculator?

 

Sunny 16 is a famous rule-of-thumb guide for film photographers wrestling with the exposure triangle:

"In sunny weather and at aperture f/16 then your shutter speed should be 1/[the ISO of your film]"

For example - in sunshine and aperture f/16 if your film has ISO 400 then your shutter speed should be 1/400. If your film has ISO of 50 then your shutter speed should be 1/50 etc.

This is an approximation of the detailed maths behind exposure calculations, and the further from mid-speed films you get then the larger the error grows. However it is an invaluable shortcut to something that will allow you to take a reasonably exposed photo without a pen and paper 😂

However this is only helpful when the sun is shining. So we've expanded our tool to account for the different types of weather you'll encounter on your film photography journey - all without needing a light meter or calculator in your pocket.