Exposures - what film taught us

I haven't been good at keeping this blog up-to-date. Recent conversations have brought up the subject of today's entry: what we used to do in the days of film to judge exposures. The rule was known as the "Sunny 16 rule", and is as follows:

f/16 for a sunny day
f/8 for overcast
f/4 for a setting sun

The shutter speed will be determined by the ISO of the film. So if we were using ISO 100, then we could be using 1/100 or 1/125. If we were to use ISO 400 then 1/400 or 1/500; it's essentially a reciprocal.

Even on a digital body that can account for the exposure, knowing the equivalent for manual exposures will help on the technical side of photography.