Sunny 16 exposure, film exposure without a meter.
Film speed and the light you are standing in; the shutter and aperture pairs that will expose the frame, including the equivalents at other apertures.
The light
Equivalent exposures
| Aperture | Shutter | Nearest click |
|---|
The rule
On a sunny day, set the aperture to f/16 and the shutter to the nearest speed to 1 over the film's ISO: ISO 100 at f/16 and 1/125, ISO 400 at f/16 and 1/500. For softer light, open the aperture: f/11 in hazy sun, f/8 under cloud, f/5.6 under heavy cloud, f/4 in open shade or at sunset. Beach and snow in full sun want f/22.
Every full stop either way is a doubling: open the aperture one stop (f/16 to f/11) and halve the shutter time (1/500 to 1/1000) and the exposure is the same. The table lists those pairs so you can choose depth of field or shutter speed and keep the exposure.
When to trust it over the meter
- Backlit subjects and bright skies fool a camera's meter into underexposing faces; the rule does not look at the sky.
- Old meters drift, and some need a battery that is no longer made. The rule is the check: if the needle disagrees with sunny 16 by two stops on a clear day, the meter is wrong.
- Indoors and at night the rule stops working; that is meter and tripod country.
Exposure value is EV = log2(N² / t) at ISO 100, where N is the f-number and t the shutter time in seconds; bright sun is about EV 15, overcast EV 13, and a lit room at night EV 5 to 7.