PDA

View Full Version : EX Aperture Scale



Diane Maher
4-Sep-2007, 05:07
I have a Beach Multi-Focal Series A lens in an old Wollensak Studio shutter and the aperture scale is shown in units of EX (11.7 is wide open and 5 is the smallest diameter of the aperture). Does anyone know about that scale and how it compares to today's f-stop system?

Diane

Jim Galli
4-Sep-2007, 06:36
Diane, I've yet to find any original literature that explains that weird scale....but....if you force 11.7 to equal f4.5 and 11 = f5.6 and count up in increments from there you'll find it is based on a Wollensak f4.5 Velostigmat and acts accordingly.

Diane Maher
4-Sep-2007, 09:32
Thanks Jim!