The Sunny 16 Rule
Posted January 17th, 2007 @ 10:46pm by Erik J. Barzeski
The "Sunny 16" Rule says that: in sunny light and with an aperture of f/16, if you use a shutter speed of 1/x (where x = your ISO), you should get a reasonable exposure.
I recently (re-)discovered the Radiant Vista site, and the thing I like most about it is the Daily Critique. I cannot imagine the amount of time the author puts into each image, and to do them daily is astounding and awesome.