Help identifying 4 tab bayonet mount.

[mumu]

Is anyone able to identify this bayonet mount? I've looked at every reference I could find and can't identify it. It's a modified or adapted M42 lens. I'm wondering if it can be undone, restoring the M42 without extensive work.

 

[AgX]

I never saw such mount before.
It could be that this alien mount is just screwd onto an M42 thread and locked by a set-screw.

 

[Ian Grant]

Knowing what the lens is would help enormously. There were a lot of very short lived European camera manufacturers after WWII, some making SLRs.

Ian

 

[mumu]

Knowing what the lens is would help enormously. There were a lot of very short lived European camera manufacturers after WWII, some making SLRs.

Ian

Its a Takumar M42 lens.

 

[mweintraub]

Its a Takumar M42 lens.

You mean "was"

 

[ciniframe]

My wild guess is a 35mm movie camera mount. But really, I've never seen anything like it either. Is it a fixed mount or just an adapter screwed onto the M42 threads?

OK, looked at the post again, sounds like not an adapter but a modification.

 

[mumu]

OK, looked at the post again, sounds like not an adapter but a modification.

The seller says it "loosens" but doesn't seem to come off. I'm thinking it might be a modified lens as well. Here's a side shot:

https://i.ebayimg.com/images/g/a~IAAOSwM49Z3nab/s-l1600.jpg

 

[BrianVS]

It looks like a Pentax 20mm F4.5, the mount looks like it can lock in with any of the four tabs. It could be custom- like used in the scientific field. Was common to modify off-the-self lenses with custom mounts.

 

[Fixcinater]

Looks like the added mount is big enough to be built onto the M42 threads, it doesn't look like anything has been removed.

I'd wager it will spin right off leaving an M42 mount ready for normal use.

 

[Ian Grant]

If the M42 thread had been modified or removed you'd need some screws to hold the alumium part in place and there aren't any. It may be the threads tight as it's a on off.

Ian

 

[AgX]

I do not know whether it is of any importance, but I find it interesting that there is mark on the lower tab.