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08-08-2013, 05:57 AM   #1
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M42 adapters and the Russian lenses

I've noticed that when you use some of he old Russian lenses with a M42 adapter, the lens mount doesn't cover the key hole on the adapter. I'm wondering if this leaves it vulnerable to dust entering the body. For that reason I don't use these sharp lenses as often as I otherwise might.

Anyone else notice this?

08-08-2013, 07:04 AM   #2
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Yes, with my MIR1. Others (I-50-2, T11-2, J6, T3) are fine. It also means that there is some play in the connection with the lens.

I have accepted not to use the lens in dusty environments and always push the lens towards the mount the same way. Although I am intrested in a more permanent solution.
08-08-2013, 08:15 AM   #3
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I use cheap fotodiox adapters, remove the locking clip, and epoxy the key holes shut. You also get light leaks, and that makes the flare problems worse.
08-08-2013, 08:30 AM   #4
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Yeah, my old Helios 40 and Industar 50 (M39-mount versions) do this. It's not an issue of play with these lenses; it's that the diameter of of the rear metal piece is too small. Light leaks are a problem. Covering the holes with my fingers helps, but sometimes I forget, like in this picture. I should just use electrical tape.

08-08-2013, 08:41 AM   #5
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Original Poster
Right, it is about the diameter of the rear of the lenses not covering the key slots of the adapter. I was wondering about the key holes being uncovered and dust getting in, but I didn't think about light leaks through those holes.

Last edited by Spodeworld; 08-08-2013 at 03:25 PM.
08-08-2013, 09:04 AM   #6
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Maybe something like this? It probably wouldn't through the infinity focus off.
08-08-2013, 11:54 AM   #7
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This is a common problem with vintage M42 German as well as many FSU (Former Soviet Union) lenses. The cameras they were made to fit (Contax, Praktica, Zenit, and such) had very narrow body flanges and the lens flanges were sized to match.

10-14-2013, 02:20 PM   #8
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I stumbled upon this thread because I'm having the same problem. Would the rings possibly solve the problem? They should just fit behind the adapter. 10 Pcs 38mm x 42mm x 2mm Nitrile Rubber Sealing O Ring Gasket Washer | eBay


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