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kevin52 · Joined: 07 Sep 2012 Posts: 1 Location: Stockton CA

I have a Graflex Optar 90mm lens serial number 287310. The shutter works but there are no aperture settings. Also there are 2 screws on the side of the wider part of the lens. The question is this: Is this lens a camera lens or an enlarger lens? I hope someone can help me. Thank you.
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Kevin T Chupp

Henry · Posted: Tue Jul 30, 2013 11:16 pm Post subject:

Can you post a photo? The enlarger lenses I'm familiar with for 35mm work have aperture settings but no shutter, as the exposure timing is usually controlled through an external device that the enlarger is plugged into in the darkroom (mine is a Time-o-Light), and runs on the order of one second through a minute. I've never seen a lens-shutter combo with no apertures!

45PSS · Posted: Wed Jul 31, 2013 7:39 pm Post subject:

What shutter is the lens in? Compur shutters use an aperture scale attached with two screws along the bottom of the shutter face plate with the speed marking and index point on the top.
f stops are a function of the lens focal length divided by the aperture opening diameter as viewed through the lens from the front.
f stop=focal length/viewed aperture opening
viewed aperture opening=lens focal length/desired f stop number
A 90mm Optar/Raptar taking lens is f6.8
90/6.8=13.235mm aperture opening as viewed through the front of the lens. Smallest aperture will be f32 or f45 for this lens.
One can easily make a scale for the lens/shutter.
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