4x5 Perfecton Wide Angle, BUT strange scale

[Jon Wilson]

I have a small M.E. Danforth Perfection Wide Angle 4x5 barrel lens which has a circular disk aperature with a strange scale. I have not been able to locate any similar scale. It does not appear to be the U.S. (Unified Scale) or a Stolze Scale. The largest aperature is marked 128, 256, 2 different size openings with a 512, 16, 32, and 64 is the smallest aperature. Can anyone advise how this scale compares with the current f-stop scale? I appreciate all assistance. Jon

[ic-racer]

Can you measure the size of each aperture opening as it appears to you viewed through the front element? Can you measure the focal length of the lens?

With this info you can figure it out.

[Ole Tjugen]

Are you sure that you are reading the correct number with the correct hole?

The largest hole should correspond to f:16, or US 16, or in rare cases Stolze nr. 16 which corresponds to f:12.5. It can't be Rudolph nr's, since Rudolph 512 would be f:2.3. Same with the "French system", 512 would be f:108!

[Paul Fitzgerald]

Jon,

that reads like the U.S. (Unified Scale) but aligned to the wrong marker.

[Jon Wilson]

Thanks for the insights. I got my handy caliber out and it appears the 6 apertures are 5.6mm, 3.8mm, 1.9mm, 1.3mm, and 1.1mm
The apparent focal length is approximately 3 inches.
If correct, then it would appear that the largest f-stop would be 13.6, 19.5, 25.4, f40, and f69.3
Does this sound correct? I hope to try this little lens out on my Pacemaker later tonight. Jon

[ic-racer]

I got 19.2, 26.8, 39, and 55 for my unmarked E&HT Anthony lens and those numbers look similar. Mine seemed to fit mathematically right between the common marked stops of today:

16 [19.2] 22 [26.8] 32 [39] 45 [55] 64

[Ole Tjugen]

If it's a 90mm/ 3 1/2" lens, the largest stop (5.6mm) will be f:16 which makes sense. The next one would then be 4.0mm for f:22, 2.8mm for f:32, 2mm for 4:45 and so on. Yours seems to skip the f:32 aperture altogether.

Assuming a small margin of error in the measurements, this makes sense to me.

[Jon Wilson]

Thank you all. This definitely will get me a good starting point. Now to find the time to expose some sheets of film. Jon

[Jon Wilson]

Here is a shot taken with this barrel lens and my Pacemaker at f64. The second picture is an enlargement of the center of the shot. These old lens truly amaze me. Jon

[ic-racer]

Thats great!