simple and useful

This is photo 101, but the sunny 16 rule is a simple and useful photo technique to use in a pinch.

The key is to match your ISO and your shutter speed and then set your aperature to 16. For different lighting conditions see the chart 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	Heavy Overcast	No shadows