Photar 50 mm, which thread?

[keks]

I just bought a Photar 1:2.8 / 50. According to this list:

http://macrolenses.de/objektive.php

i was expecting an M40x0.75 thread, but actually its something in the range of 33-34 mm. The scale of my Photar ranges from 2.8 to 11.

Can anyone tell what thread it has?

[Choronzon]

Can you please post a photo of yours? I have a 2.8 as well as an 80mm photar, and can assure you they both have the 40 .75 thread and fit directly into the Aristophot standard shutter with no adapters.

[Charles Krebs]

and can assure you they both have the 40 .75 thread and fit directly into the Aristophot standard shutter with no adapters.

This is the same front mount size for all "#1" shutters I have seen (Copal, Compur, Prontor).

[ChrisR]

Reading between the lines - are you sure it doesn't have an adapter screwed tightly to it?

[g4lab]

My example of the 50 2.8 Photar has a 39mm Leica screw thread mount like any enlarger lens.

There was a 50mm f4 version that had an RMS thread.

The 40 /0.75 thread was used on the Polaroid MP 4 /Tominon lens sets.(which had a Copal #1 shutter)

[g4lab]

Never wanting to contradict "Choronzon"(nor Dr.Klaus Schmitt's web pages), I measured my 50/2.8 Photar. It measured 38.69 mm OD and would not engage threads at all, with the 40mm female thread on a Polaroid MP4 Copal #1 shutter.

I guess they made different mounts for different applications.
The numbers screened onto the aperture scale do go from 2.8 to 11. There are a few clicks beyond but they have no numbers. Very nice diaphragm with lots of blades and very round aperture.

[keks]

Thx everybody, seems there are lots of versions. Actually mine has that nice round aperture too, 15 blades actually. ...and im not aware of any adapter ring.

I have now identified the tread using a caliper for the diameter and a macro-photo together with a mm-scale for the lead (actually i believe that is a quite good technique for small scale measurements).

Result: M34x0.5

I want to adapt it to M42, actually i have just found a M34x0.7 to M42 adapter till now, maybe that one works.

Here are some pictures:

[Choronzon]

Mine is definately 40 .75 as is my 80mm photar, and all my other summars with the 40 0.75 adapters for aristophot. I read long ago that the 50mm 2.8 was especially made for transmitted light only, with the Aristophot diascopic illuminator. It's possible to get Kohler illumination with this setup by focusing and centering the bulb on the back pupil of the 50mm lens. It's also possible to get the whole diascopic base centered so the smaller inlay rings are used as a field diaphragms. Used like this, it's possible to get very high resolution 4x5 film photographs with such specimens as whole thin section mouse embryos and brain sections. I have some 4x5 color transparencies of whole mouse embryo thin sections that have been tri color stained years ago. I can assure you there is no way to get better lower power transmitted light photomacrographs than with a diascopic illuminator with adjustable condenser lenses matched to the lens in use.

[lothman]

Mine is definately 40 .75 as is my 80mm photar, and all my other summars with the 40 0.75 adapters for aristophot.

Yours shows a slotted ring and therefore a bigger outer diameter at the thread, keks' does not, so maybe this ring is missing on keks' photar.

[Choronzon]

I think you're right, lothman. Since there are 3 documented types in this thread, perhaps the mounting thread is added on as a flange secured with a ring to secure it by the factory. It would make sense if this lens was meant for multi instrument use.

[g4lab]

The ring of brass containing the Leica thread on mine does look like it could be unscrewed. I did not see any grub screws holding it so I suspect it is threaded on tightly and was not interested in attempting to break it to see if the thread underneath matched keks as seems rather likely.

It was on very solidly and 'if it ain't broke" don't try to fix it.

[g4lab]

I can assure you there is no way to get better lower power transmitted light photomacrographs than with a diascopic illuminator with adjustable condenser lenses matched to the lens in use.

That's why the Aristophot was the Aristophot.