How to Use the Sunny 16 Rule

Aperture f/16 use shutter speed of 1 over ISO on a bright sunny day, that’s the basic jist of the Sunny 16 Rule.

Conditions Settings
Sunny ISO 100 f/16 1/100s
Slight Overcast ISO 100 f/11 1/100s
Overcast ISO 100 f/8 1/100s
Heavy Overcast ISO 100 f/5.6 1/100s
Shade ISO 100 f/4 1/100s

Back in the day, camera lenses had clicky aperture stops and the Sunny 16 Rule corresponds to these stops.
The common aperture stops were f/1.0, f/1.4, f/2.0, f/2.8, f/5.6, f/8, f/11, f/16 and f/22.
We need to compensate 1 stop for each change in light conditions. Bright sunny conditions have sharp, well defined
shadows. Slight overcast has soft shadows and overcast barely has any shadows from the Sun. Compensate 1 stop for
backlit or snowy (bright white) situations.

I shoot my Canon 6D DSLR like I shoot slide and still use the Sunny 16 Rule. To keep shutter speed up and lens sharp,
my most commonly used settings are based on ISO 200 f/8 1/800s.