Dan, Of course you are right about the aperture diameter, but the OP asked about aperture scales, not aperture diameters. You are also quite right about the difficulty in physically measuring delicate aperture diameters and optically measuring small entrance pupils. The entrance pupil of my Leitz Super-Angulon 21mm is 0.65mm at the smallest aperture, not easy to measure with the 1mm graduations on my transparent scale.
Jim, thanks for the reply. Thing is, the distance between each pair of the aperture scale's tick marks corresponds to a one stop change. What the f/ numbers are depends on the diameter of the lens' entrance pupil and the two openings' sizes, but regardless of the entrance pupil's diameter and the openings' sizes, moving the aperture indicator from one tick mark to the next will change the f/ number by one stop.
I agree with that.
I mounted a super angulon 90 in a copal press with starting point f 4,5.
I measured the opening for different apertures an got the following result:
F8 starts at between 5,6 and 8 on the scale, f11 was a little more than 8. F16 was 11, f22 was 16, f32 was 22, f45 was between f22 and 32 and finally f64 was f32. It is difficult to measure exactly so it can be a bit off. I used a calipers and for the smaller openings transfered measure to a pencil I carefully positioned in the hole. So i am planning to flip the scale and
Make a new scale on the back of the original scale. But fir now I can roughly use f16-f32 just by using one less fstop on the
Scale scale.
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