View Full Version : Historic Aperture Systems

Mark Sawyer
9-Aug-2010, 18:49
As most of us who use old lenses know, there were a number of different systems used to calculate and define the aperture variations on a lens. I'm curious whether anyone knows of a resource that cross-matches the equivalents of the different systems?

BTW, here are the systems I know of:

f/stops (aka, the "International System")

Continental System (same as the f/stop system, but with the standard stops in different places, ie: 4.5, 6.3, 9, 12.5...)

Alternative System (same as the f/stop system, but with the standard stops in different places, ie: 3.5, 5, 7, 10...)

Uniform System

APEX System

Stolze System

Dallmeyer/Goerz/Voigtlander Systems (same as the Stolze system, but with the standard stops in different places along the scale)

French System

Zeiss System

Anybody know of any others? (Apparently, some very early lensmakers assigned arbitrary values. but we won't count those!)

9-Aug-2010, 19:15
There is a chart at the end of the extensive article on aperture here:

Mark Sawyer
9-Aug-2010, 19:29
The chart on Wikipedia differs from the chart on page 128 of Sidney F. Ray's Applied Photographic Optics:


...in that the Wikipedia chart has different values for Voigtlander, Dallmeyer, and Goerz, while Ray's chart has them being the same system. Hmmm...

Wade D
9-Aug-2010, 23:01
Very good info so far. A couple of my old lenses use US stops. I don't have the chart at hand but not hard to figure out.

Dan Fromm
10-Aug-2010, 02:54
Les Chiffres Cles, a little book by Patrice-Herve Pont, contains a clear exposition of many aperture systems, also tables giving serial numbers vs. dates for many lens and camera manufacturers. I bought mine from Atlantida-Seguier, FNAC has it too. I think the 3d edition is still the latest.

Sorry that I can't list the aperture systems Pont reports, I'm at work and the book is at home.

10-Aug-2010, 03:59
I have a 300mm f9 Cooke Apotar lens with the apertures marked in conventional f stops and millimeters.

nn :)