Originally posted by lytrytyr Half a stop is half a stop, wherever it's at.
Originally posted by Wikipedia: In photography, stops are also a unit used to quantify ratios of light or exposure, with each added stop meaning a factor of two, and each subtracted stop meaning a factor of one-half.
Therefore, a stop is either half the light or 2x the light, wherever it is at.
If you start say at 100 light units at f4, you get 50 light units at 5.6, and 25 light units at f8.
Edit: Math fixed. Thx @lytrytyr
If you start with 100 light units at f4, you get 200 light units at f2.8, 400 at f2, 800 at f1.4, and 1600 at F1. The difference between 1.4 and 1 would be 800, but since it's half a full stop we're talking about, it's similarly 400 light units.
Last edited by Clinton; 01-16-2013 at 08:25 PM.