The sunny sixteen rule

The sunny sixteen rule is a traditional method of correctly estimating daylight exposure without a light meter. The rule states that on a sunny day—using an aperture of ƒ/16—set the shutter speed to the reciprocal of the ISO setting (or ISO film speed) to correctly expose a subject in direct sunlight.

That is—according to the sunny sixteen rule—if you shoot at ISO 200 (or using ISO 200 film), the correct exposure will be ƒ/16 at 1⁄200 sec. You can also use a larger aperture if you adjust your shutter speed accordingly.

The following exposures use ISO 200.

• Sunny day in direct sunlight – 1/200 at ƒ/16

• Sunny day with distinct shadows – 1⁄250 sec at ƒ/16

• Hazy sunlight with soft shadows – 1⁄125 sec at ƒ/16 (or 1⁄250 at ƒ/11)

• Cloudy bright with no shadows – 1⁄60 sec at ƒ/16 (or 1⁄250 at ƒ/8)

• Heavily overcast or open shade – 1⁄30 sec at ƒ/16 (or 1⁄250 at ƒ/5.6)

• Sunny day on snow or light-colored sand – 1⁄500 sec at ƒ/16