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David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 1
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 18, 2009 - 02:04 am: | 
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Hi; long time no been here. Hope someone here knows more about this stuff than I do.
I just got done rebuilding one of my Zorki-3Ms. (Long story why I ended up with 2; eBay snafu.) Works fine for the most part. But both of these cameras had a fairly serious problem, one that I managed to cure on this one (the other one awaits).
The problem is that as assembled, the lens register distance (the distance from the lens mount flange to the film plane) was much too far. (Going by the 28.8mm standard, which translates to 1.134" in American units.) So there was pretty much no way that anyone could have taken reasonably sharp, in-focus pictures with either of these cameras, at least not intentionally.
It was so bad on this one camera--off by more than 0.010"--that I had to grind down the front plate (not the lens mount but the thing it attaches to), plus I actually had to carve away some of the vulcanite around the lens mount.
Has anyone else delved deeply enough into these cameras to know about this problem? Or maybe with another SovCam? Having worked on a bunch (mostly FED-2s), I've never seen one that didn't need some lens-mount shimming to bring it out to the required distance. |
John_cribbin
Tinkerer
Username: John_cribbin
Post Number: 13
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, December 19, 2009 - 12:23 am: |
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Hi David,
The gray cells are a bit rusty as it's a long time since I've taken any of these appart ...
I've got most of the Soviet rangefinders and have done a fair bit of work over the years on all the FED's and Zorki's. As I recall, they all share the same 4 hole mounting and screw pitch so they are interchangable. But there are variations in thickness between some models. So you can swop the parts without problem until you try to set up the working distances.
I suspect that what you have is a camera that had a damaged / ugly mounting ring replaced from a different model giving you the issues you have now.
I think a lot of sellers have made the cameras look pretty by changing parts, fairly safe in the knowledge that hardly anyone is going to put a film through, or even know what the distances are supposed to be.
Cheers
John |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 7
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, December 19, 2009 - 12:59 am: |
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Thanks for your reply.
I do know about how parts get swapped around, sometimes pretty promiscuously, on FEDs and Zorkis. But in this case I don't think this is necessarily the issue.
The Zorki-3M (as well as the -3 and -4) are built a little differently from the other, earlier cameras (like the FED-2 and the Zorki-1 and -2) in that the lens mounting ring doesn't mount directly on the body. Instead, it mounts on an intermediate plate that is screwed to the shutter crate, forming the front of a box. The body fits around this plate. There's a projecting ring on the plate which is what the mounting ring screws onto. This projecting ring is what I had to literally grind down.
You are correct that all the SovCams share the same 4-hole mounting and lens screw pitch (39mm), but they are not all interchangeable from one model to another. Some of the other ones (FED-2, I believe) have a relief cut at the top to clear the top plate; the one for the Zorki-3M is plain all around. The screws are different as well; I ended up using a screw from a FED-2, which is longer, because one of the ring mounting holes stripped and I had to put a nut behind it.
Still in all, what you said about sellers not really caring about such niceties as lens register distance is a real possibility. In any case, the register is now set correctly on this camera. |
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