Help! Leitz lens identification

[Lexa]

Recently I've came across very unusual lens - Leitz Epar 600mm f/4.5. The lens has fixed iris (a little bit smaller than internal body diameter), also it seems that front and rear elements are cemented doublets and there is another glass with a little (if not flat) curvature in the middle. No signs of coating at all. Body of the lens consists of two parts - internal (which holds all the glass) made of chromed brass and outer made of brass and black painted. There is some kind of focusing mechanism (like one used in projector lenses).

Unfortunately I can't find any information about this giant beast (and it's really huge one!). Can you tell me any information about the lens?

Thanks!

[Louis Pacilla]

More than likely a triplet projection lens. I have seen them on eBay every now and then.
They do not usually get big money.

[alon96]

I also have a Leitz lens150F6.3, again without any information.

[Sevo]

Going by the name, yet another episcope lens - Leitz used to be the market leader in these precursors of the overhead projector, installed in every German lecture room...

The resolution requirements were modest, but the lenses are fast and generally have enough coverage for at least 5x7", so they lend themselves to abuse as a low DOF large format portrait tool. They are mostly triplets, but I've also seen Tessar and double Gauss types and supposedly the longest focal length ones are Petzvals.

I bought mine from various surplus stores, for scrap value (i.e. well below 20€ each).

[Steven Tribe]

I think most Leitz projection lenses are straight original style "Cooke patent" triplets with single lenses (not achromats) front and rear. Cheaper to make and more reliable in use.

[Lexa]

Thank you for your prompt answers!
Still it's not clear for me The lens definitely has cemented doublets in front and rear and single element between them. The internal structure of this Epar looks like Heliar, thus it's not classic Triplet/Petzval type May be further development of Tessar projector lens...

And the lens is huge - glass diameter is about 128mm (5"), length - ~10" and weight some 5kg. It easily covers 11x14" and even more. I can't imagine what kind of projector may use that big lens...

[Steven Tribe]

There are recent earlier threads which discuss these projectors.
They had to be big:
-Illuminate a large lecture room.
-Avoid being stolen by Students etc.

[Dan Fromm]

And the lens is huge - glass diameter is about 128mm (5"), length - ~10" and weight some 5kg. It easily covers 11x14" and even more. I can't imagine what kind of projector may use that big lens...

You should have your imagination overhauled.

http://www.markerink.org/WJM/HTML/epimonst.htm

http://www.markerink.org/WJM/HTML/diaskop.htm

http://www.markerink.org/WJM/HTML/epidiask.htm

http://www.markerink.org/WJM/HTML/Ze...Epidiaskop.htm