Probability, whether high or low, says something about our expectations. Not about the thing we have those expectations about.
It would be fun to see a series of test images made using this lens, in all configurations.
No, no diaphragm and the mechanism doesn't allow for one either it seems.
The lens mount (which is cast!) has threads into which the two units screw into....the lens spacing as shown in the diagram is correct as far as right and left units are concerned. Spacing of the two main units to each other is correct within 1/4 inch. I am not sure how the whole assembly was mounted, and whether it was encased, and how. The retaining rings at the ends of the lens are well made and there is nothing missing there.
Given that the serial number was CAST with the lens mount, there must be quite a few of them. The recurrent serial is 1095-18xx, with the individual pieces then labelled with scratched in numbers.
I'm not sure how to tell how many examples of a lens were made. The s/n smells like an Elcan one. These have the form tttt-nnnn, where tttt is the lens' type and nnnn is the individual lens' sequence number. There's no type 1095 in my Elcan C-series reconnaissance lenses catalog, but this proves nothing.
I'd been doubting that its an aerial camera lens because it seems to have come apart easily. The ones I've had (1 Ross, 1 S.F.O.M., 1 LOMO, 3 Elcan, 3 TTH, 20 Zeiss) were all made to be hard to disassemble. This to resist vibration. But again, if yours came apart easily that proves nothing.
Now, here http://cgi.ebay.de/Objektiv-Leitz-We...item4152f5129c is a gross monstrosity of a projection lens.
Which i still would bet Dirk's lens is: a projection lens.
The epi(dia)scope option is certainly something to be followed up. I have trouble finding lens sections of the lenses, though. It clearly isn't a Leitz...
The problem is that the lens mount of the unit I have in hand does not have a focusing helicoid, which is required to focus the projected image (as a student in the 1970s I used these monster devices to project pages from books for discussion in tutorial presentations). It looks more like a fixed focus unit.
And all cinema projection lenses (which would have a fixed projector to screen distance once installed) I can find are smaller..
Also, all projection lenses I have seen, although exposed to the heat of the lamps, don't have these weird holes...
I have been toying with the idea whether it could be an 'eye-piece' of a very large telescope, but all the cross-sections i can find there are also different...
To add some more food for thought, see the lens with the "holey" mount in this thread:
Absence of a focusing helicoid is consistent with a naked (out of its cone) aerial camera lens. I've seen two ways of collimating aerial camera lenses to the camera.
The lens screws into a mount called, by convention, a lens cone, is screwed in or out to collimate and is then locked in place; examples that I've seen include Vinten F-95; AGI F134, F139, and Agiflite; and Omera 31. The cone is bolted to the camera body or bayonets into it.
The lens (in shutter) is bolted to the camera main casting, shims between body and back of shutter adjust flange to film; this is how the 38 Biogons in the AGI F135 were collimated to the camera.
Thanks for the link. Some time ago I wrote an essay in which I characterized most aerial camera lenses as poisoned gifts. I think that fits the 7"/2.5 Aero Ektar adapted to M42 mount shown in the link.
Anyway, I agree with the person who responded that the holey lens shown in that thread is part of a condensor. It has the look, and I'd swear I've seen similar things offered as condensor lenses. Your monstrosity doesn't. Could be mistaken, though, about the lens in the link. I don't believe that condensor lenses are often as elaborate as the monstrosity.
Why do you think that Leitz bought in lenses for their Epidiascopes?