Yes, the rim eliminates it as a standard LTM adapter. It's almost certainly the bayonet from a Summaron or Summicron convertible.
Somewhere in the world is the matching screw mount lens to go with it! They are desirable as they close focus to 0.7m, unlike other screw mount lenses, so one gets the best of both the thread mount and bayonet worlds...
Somewhere in the world is the matching screw mount lens to go with it! They are desirable as they close focus to 0.7m, unlike other screw mount lenses, so one gets the best of both the thread mount and bayonet worlds...
FrankS
Registered User
Our first step forward with your mystery was to determine that the camera has a standard m mount and that the screw mount visible was just an adaptor. The next step is to determine what kind of adaptor it is. I'm in with the convertible Summaron adaptor theory, because of that lip and set screw.
Muggins
Junk magnet
OK< that now makes sense, I think. It seems odd to me that a lens part would be used as an adaptor to fit a microscope, but then if it were needed to fit a part carried over from earlier microscopes built to fit screw-mount cameras...? If, if there was ever the rest of a lens to go with it I suspect it's long vanished, but I will keep an eye out just in case.
(Call me stubborn, I still suspect that camera and microscope were supplied together - though no-one is left who'd remember, and I don't see why you'd supply a whole lens in that circumstance).
I'll have a look at the J-8 whatever because the guy who has it also has an M6, is a good bloke, and will be useful to talk to about both M and LTM lenses. I'll also hopefully get the opportunity to explore some over the Christmas break as I plan to visit a shop in Cambridge (UK) that will stock various lenses in both mounts and I can think about options.
Cheers, guys!
Adrian
It's a standard 39mm thread so it's possible it could work with a microscope adapter, as well. But I suppose it's also possible the camera could have had a 35mm lens on it at some point in its life, maybe it wasn't dedicated to just one task.
HuubL
hunter-gatherer
Sykomor
Established
So that's what I have in one of my strange items boxes. It does not fit the Jupiter-8. I just tried.
Muggins
Junk magnet
Me again...
Having at long last got a film through it, it seems that the slower speeds are definitely misbehaving, but the faster ones seem fine and the only restriction is the nut that holds the camera (as ever...).
So... As a CLA will be a "when I get a Round Tuit" job, just out of curiosity which speeds are on the slow escapement? My Google-fu seems to be failing me on this one, or possibly I'm just not patient enough to keep googling when I know someone here will tell me in an instant.
Cheers,
Adrian
Having at long last got a film through it, it seems that the slower speeds are definitely misbehaving, but the faster ones seem fine and the only restriction is the nut that holds the camera (as ever...).
So... As a CLA will be a "when I get a Round Tuit" job, just out of curiosity which speeds are on the slow escapement? My Google-fu seems to be failing me on this one, or possibly I'm just not patient enough to keep googling when I know someone here will tell me in an instant.
Cheers,
Adrian