Co wikipedia mówi o tym problemie?
http://en.wikipedia.org/wiki/F-number
(skala co pół stopnia)
Typical one-half-stop f-number scale:
f/# 1.0 1.2 1.4 1.7 2 2.4 2.8 3.4 4 4.8 5.6 6.7 8 9.5 11 13 16 19 22
(skala co 1/3 stopnia)
Typical one-third-stop f-number scale:
f/# 1.0 1.1 1.2 1.4 1.6 1.8 2 2.2 2.5 2.8 3.3 3.5 4 4.5 5.0 5.6 6.3 7 8 9 10 11 12.5 14 16 18 20 22
Notice that sometimes a number is ambiguous; for example, f/1.2 may be used in either a half-stop[1] or a one-third-stop system[2]; sometimes f/1.3 and f/3.2 and other differences are used for the one-third stop scale[3].