Help - Aperture Sequence in Dallmeyer Wheel Stop Lenses

[Richard K.]

I have two Dallmeyer WAR type lenses and would like to know the f-stop sequence for the apertures on the wheels. It's hard to measure their diameters precisely to relate to the wide open one. Is there a published scale, or has one of you determined this? The lenses are:

Dallmeyer Wide Angle Rectilinear No.1 7” f/16 1895

This one has 6 stops including the maximum hole.

and

Dallmeyer Wide Angle Rectilinear No.3 13” f/15 1867

This one has 5 stops including the maximum hole.

I'm also not 100% sure about the maximum aperture I have stated but I think it's right based on the D.O.B. of the lens. It would be nice if they just went f/16 or 15, f/22, f/32, f/45, etc

Thanks for your help!

[Chauncey Walden]

My 135 Dallmeyer WAR (1886) has a normal progression - 16, 22, 32, 45, 64

[Richard K.]

My 135 Dallmeyer WAR (1886) has a normal progression - 16, 22, 32, 45, 64

Thanks Chauncey. May I ask how you know this? Did you measure or read somewhere? If read, where? You say it's a 135 - is that mm? How many holes does your wheel have?Thanks!

[Chauncey Walden]

Richard, I finally got around to digging it out and found that my memory had partially failed me. It has 5 stops and they are marked on the wheel in Dallmeyer's unique numbering system as 22.5, 45, 90, 135, and 180. This correlates (approximately) to f/16, f/22, f/32, f/32 1/2, f/45 (close enough for the film anyway.) I had forgotten about the odd half stop between f/32 and f/45. The number appears at the top of the wheel when its stop is in position. Of course if you really want to base your exposure on f/15.3 instead of f/16, you could carefully measure the focal length of the lens at infinity to the stop and measure the apparent diameter of the stop through the front lens and do the division. Here's a low res image from my Dallmeyer at "f/32".