I would like to know how accurate should the aperture hole size be by measurement using a vernier caliper. On some lenses viewing through either the front or rear cells seems to offer optically different size of aperture and measuring the shutter alone is vastly different (smaller). Which is correct? Should one view through the front or rear cells. And leaving the lens complete or with just one of the cells?
I have found the engravers art to be quite variable in that while some apertures will measure accurately others will not. Which aperture would one pick as the lynch, 16, 22? Is there an industry standard re error? 1/3 stop? More?
All this came about when a lens seller offered a near new Clarion with an old silver dial Copal. Starting at 6.8 ???
I find the black dial small serrations Copal to have at times a quite loose (free) aperture ring. What is the best way to firm this up?
Finally can anyone tell me the meaning of the numbers printed on the aperture scale? Are these lens related and if so how to source this info? [ No not the aperture #’s but the very small ones.]
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