Rules to Remember* Sunny 16 Rule-
What it is: Method of estimating correct exposures for daylight without a light meter.
The rule: On a sunny day and for a subject in direct sunlight, set aperture to F16 and shutter speed to the reciprocal of the ISO. Example: Aperture at F16, ISO at 100, shutter speed at 1/100. Your shutter speed and aperture can be changed from there as long as the F-stop is altered to compensate (think of how Program, Aperture Priority, or Shutter Priority settings work on a camera). Example: 1/250 at F11 gives an equivalent exposure to 1/125 at F16.
* F8 and Be There-
What it is: In photojournalism, this classic saying refers to getting "the shot" and came from when newspaper photographers had pre-focused cameras set to F8 (also without automatic settings and light meters).
The rule: Keep your aperture set on F8 (when not on controlled photo shoots). By pre-focusing, setting your aperture to F8, and setting the shutter speed according to the Sunny 16 rule, your camera is set to "grab and shoot". Approximately everything from about six feet to infinity should be in focus. This setting is good for when things happen quickly and you don't have time to trial and error (manually), or have your digital camera set automatically and handy.