Sunny 16 Exposure Calculator

Frequently Asked Questions

How accurate is the Sunny 16 rule?

Accurate enough for negative film and a good starting point for digital. Negative film tolerates a stop or two of error in either direction; digital highlights clip without warning, so use the Sunny 16 result as a baseline and refine with the histogram.

What does 'open shade' mean?

Open shade is shadow lit by a large open sky but not by direct sunlight - under a tree with clear sky overhead, or in the shadow of a building on the north side. It typically needs f/4 or about two stops more than direct sun.

Can I use Sunny 16 for indoor shooting?

Not reliably - indoor ambient light varies too widely for a single rule. Sunny 16 is designed specifically for outdoor daylight conditions.

How does this relate to an exposure value (EV) chart?

The Sunny 16 rule corresponds approximately to EV 15 at ISO 100. Each lighting condition in the table shifts the EV by one stop. EV 15 (bright sun) down to EV 12 (overcast) matches the aperture steps in the rule: f/16, f/11, f/8, f/5.6.

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Estimates for informational purposes only.

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.

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How It Works

The Sunny 16 rule is the classic meterless exposure method: on a bright sunny day, set aperture to f/16 and shutter speed to approximately 1/ISO seconds. At ISO 100, that is f/16 at 1/100 s; at ISO 400, f/16 at 1/400 s. The rule is derived from the fact that direct sunlight at sea level produces a fairly consistent luminance around EV 15.

Different lighting conditions shift the reference aperture: f/11 for slight overcast or haze, f/8 for overcast, f/5.6 for heavy overcast, f/4 for open shade or near sunset. To use any other aperture, the shutter speed scales by the stop difference: opening one stop halves the shutter time; closing one stop doubles it. The exposure value stays constant throughout.

This calculator applies those stop differences automatically across all common apertures and displays a complete equivalent-exposure table so you can see every valid combination at a glance.

Use Cases

The Sunny 16 rule is valuable in many practical situations:

Film photography when the built-in meter has failed or batteries are dead

Shooting manual cameras that have no built-in meter

Sanity-checking your camera's meter reading in tricky lighting conditions

Teaching beginners to think about the exposure triangle without relying on auto modes

Developing an intuitive sense for exposure so you can predict settings before raising the camera

Tips

For backlit subjects, open 1-2 stops beyond the rule's recommendation to prevent underexposure of the subject.

Snow, sand, and highly reflective surfaces need f/22 or closing one stop extra to prevent blowing out the highlights.

Remember that ISO drives the shutter speed in this rule: ISO 400 gives 1/400 s at the reference aperture, not 1/100 s.

Slide film and digital highlights are less forgiving than negative film - if in doubt, expose slightly conservatively and review the histogram.

The rule works best in mid-latitude locations at midday sun; at golden hour the sun is much lower and you may need to open 2-3 stops beyond the rule's estimate.

FAQ