Quote Originally Posted by jochen View Post
before WW II the old f-stop system was often used: 2.2 / 3.2 / 4.5 / 6.3 / 9 / 12.5 / 18
Not by many manufacturers, my 1913 CZJ 165mm f6.3 Tessar has the tradional 3, 5.6, 8, 11, 16, 22, 32, in fact of all my pre-WWII German lenses (over 16) only my Summar has the other syste.

Ian