Schneider - Kreuznack Symmar-s 5.6/210

[Arne Croell]

Roughly you can also measure the distance you move the slider from f32 to f45, the distance to f64 from f45 will be less. This is only a rough estimate but will get you in the ballpark.

Actually thats true only for older shutters like the Synchro-Compur that used circular aperture blades. Since this is a Symmar-S, not a Symmar, I assume the shutter is similar to a modern Copal or Compur (or Prontor), where the distance on the scale is evenly spaced between apertures. Its easy to see, if the other markings from f/5.6 on down are evenly spaced then f/64 is the same distance further down (not taking into account any increased tolerances at the end of the aperture lever movement)

[Jan Pedersen]

Arne, Thanks for the correction, good that some are awake when they write here.
I use mostly older shutters and never thought about the evenly spaced f stop distance on Copal shutters.