I've got a nice Copal 1 shutter that came with a lens (Caltar II, 210 mm). The shutter is marked for f-stops from 5.6 to 64. Having come across a G-Claron 305 lens set (no shutter), I've discovered that the elements are threaded so they fit the Copal 1 perfectly. My question: Just because the f-stop markings indicate a maximum opening of 5.6, does that mean that any lens set that fits the Copal 1 shutter will also have a maximum opening of 5.6?
My sense is that the G-Claron is actually more like an f9, so I'd simply make a chart that starts with "marked" 5.6 = 9 "actual" and work the remaining f-numbers from there. Then a quick test shot or two would confirm I'm in the ballpark.
Looking forward to hearing your thoughts.