Some questions on brass lenses.
1) If one has a lens with rear element that is 75mm diameter but the largest Packard shutter that can be used has a 2.5" (63.5mm) opening, how 'bad' is it to lose about 15mm of aperture. It seems reasonable to consider the lens has been stopped down from an f/8 to a bit more (f/10?), so not a major deal. I realize the shutter is acting as an Exit Pupil and not a conventional stop. Front mounting the shutter is out of the question due to aesthetics.
2) I assume a bare brass lens should never be polished clean as new as this ruins the patina
3) For a lacquered brass lens if there are 'many' areas of exposed brass turning dark would stripping / cleaning and re-lacquering be reasonable approach.
4) Should the Iris have a small quantity of graphite dry lube applied?
Regards,
Tim
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