Page 2 Russ Campbell

Sunny 16 Rule by Russ Campbell

Back in the day when we took photos with a film camera that did not have a built-in light meter, we needed a quick way to estimate our exposure settings and many of us used the Sunny 16 Rule.

Even with today’s sophisticated cameras and their powerful built-in computers and metering systems, the old rule of thumb can act as a valuable teaching aid for learning more about the exposure value (EV) system—the very core of photography.


So what’s the Sunny 16 Rule? It’s a method for estimating correct daylight exposures without a light meter. And, even when you are able to meter the scene, because the rule is based on incident light rather than the reflected light that most camera light meters measure, the Sunny 16 Rule can also be used to estimate exposure values for difficult subjects, where, for example, very bright or very dark subjects have to be compensated for.


The rule states that on a sunny day set your aperture to f/16 and your shutter speed to the ISO—or more correctly, the reciprocal of the ISO.

Following the rule:
• On a sunny day and with the camera set to ISO 100, set the aperture to f/16 and the shutter speed to 1/100 (on many cameras 1/125 second is the available setting nearest to 1/100 second).
• On a sunny day with the camera set to ISO 200 and aperture at f/16, set shutter speed to 1/200 or 1/250.
• On a sunny day with the camera set to ISO 400 and aperture at f/16, set shutter speed to 1/400 or 1/500.
Shutter speed, of course, has to be adjusted to suit the circumstances. If such is the case, alter the aperture (f-stop) to compensate, e.g., 1/250 second at f/11 gives equivalent exposure to 1/125 second at f/16.


The above works very well for most situations on sunny days. So what about cloudy or overcast days? Well, for those days we use a sliding scale as outlined in the table below.

Aperture Lighting Conditions Shadow Detail
f/16 Sunny Distinct
f/11 Slight overcast Soft around edges
f/8 Overcast Barely visible
f/5.6 Heavily overcast No shadows

For quick reference, here’s a list of the (full) f-stops:
f/1 f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22 f/32 f/45
That’s it. have fun.

© 2009 Russell G. Campbell
All rights reserved.