What mount is this?

Tom A · 08-11-2012

I have this strange Canon Serenar 50mm f1.5 - except that the mount is for something else. It looks like s 'stock" 50f1.5, focussing helicoil works as it should, aperture is fine - but the 39 mm lens-mount is either removed or the new mount is threaded on to it. Not a "hack" job either, though you can still see the tool marks in the cut, Even the lens can (marked Serenar 50mm f1.5) has a custom fitter metal ring that will hold the lens with a simple push-fit.

Tom A · 08-11-2012

It does look like a stock 50f1.5 Serenar (and is in remarkably good condition for its age). initially I had hoped that the strange mount was screwed in from the "camera" side - no such luck. I am going to have to take out the lens element "head" as well as undoing the helicoil and see if I can access the screws from that side. I also hope that they simply threaded the mount on to the 39mm thread - rather than remove it in its entirety!

hipsterdufus · 08-11-2012

If you got a parts Jupiter 3, I wonder if you could shoehorn the optics module into the J3 mount... Just a thought.

Brian Legge · 08-11-2012

Interesting.

I picked up a Canon 50mm 1.5 a few months ago in parts. Unfortunately it was missing a retaining ring of some sort so there wasn't anything to optical module in place. It sounds like yours is in nicer condition, mount aside, as the glass in mine isn't in great shape.

I held on to it as a parts lens thinking I'd do something interesting with it some time. Let me know what you find out.

sebastel · 08-11-2012

to me, it looks like the lens mount was removed from some camera and screwed onto the lens. just a weird guess, though.

regards,
s.

Tom A · 08-11-2012

Quote:

Originally Posted by sebastel

to me, it looks like the lens mount was removed from some camera and screwed onto the lens. just a weird guess, though.

regards,
s.

I thought of that too - but why? There would be no practical way to attach it. Screwholes are blocked. It will be interesting once I get the mount off. If there still is a 39 mm thread left - all I would have to do would be to check focus and shim if necessary. If not, I might sacrifice a screw-to- M adapter and have a M-nount Serenar 50mm f1.5!!!!!

farlymac · 08-11-2012

I was hoping when I saw the cut on the one side, that there would be a corresponding cut on the other side, so that you could use a flat spanner to remove the mount. It does look like it is screwed on, so if you could get some kind of grip on it, it might just spin off. Maybe this was a modification to mount it on a large format camera, and the cut is a registration device.

PF

farlymac · 08-11-2012

Just looked at your other post, and I think you'll have to tear it down anyway, to clean the elements.

PF

alfredian · 08-11-2012

Does the jerry-rig job match up to any type of lens board? Somebody wanted a bellows-mount sheet-film Canon? The straight-edge is for what? orientation? clearing a viewfinder? The E-P suggests an American was involved at some point? Can-Am appurtenance for NASA?

DaveP · 08-11-2012

That sure does look like a Fed or Zorki mounting flange screwed on there. Ive had those flanges off quite a bit and one or the other has that flat machined in it to so the top will slip in. Probably just stuck on there, use a pair of needle nose as a spanner in those holes to unscrew it.

farlymac · 08-11-2012

Now that you mention it, Dave, it does look like a Zorki mount. Could be that the lens is stuck in the threads, and the user drilled out the screws from the back side to get it off the camera. I'd cut a slot in the mount to be able to spread it a little before backing it off. It may mean having to cut right through the threads of the lens to do that, unless you can do it at an angle that would spare the lens threads. You might get a large pin spanner that is used in certain mechanical applications. You can generate better torque that way, with less slippage.

PF

ChrisN · 08-11-2012

Perhaps some careful heating with a micro-torch ...

Tom A · 08-11-2012

There are screws showing at the bottom of the holes - 2mm pitch. The intrude about 3-4 mm - but the heads are inside the mount - hence it has to come apart.
It is definitely not a "hack-job" - somebody went to a lot of effort to put it together - and the "lens can" with its threadless base and push-fit ring is a designed product.
Will be an interesting project once I get some spare time.

DaveP · 08-12-2012

Very bizarre! Please let us know what you find out. But, just for grins, go ahead and try the spanner trick on it,, the holes for the screws in those mounts are countersunk and could make it appear as if they have been screwed in from the other side. There is just no explanation for the mount to be permanently mounted to the lens, it will fit nothing. It may be that the lens was stuck on the camera and someone destroyed the whole thing to get to this point. Fascinating mystery though.

buzzardkid · 08-12-2012

Fast lenses were also used for X-ray equipment.

This may have been modified to fit an X-ray camera, although it would have been strange the aperture wasn't removed at that point: the X-ray lenses are used wide-open and no aperture is required...

I'd simply transplant the whole optical block into another Serenar 50/1.5 mount from a shot lens, then shim it. Shouldn't be hard to find one, when taking some time or asking some reputable sellers from Japan online...