Help Identifying This Lens?

[Punkinhed7]

Got this lens in a lot of stuff recently and am having the darndest time figuring out what it is.

I've poured over the lens with a loupe and can't find a single marking on it anywhere--either cell--to indicate the make. What piqued my interest is that the coverage seems to be pretty large for such a small lens. It appears to easily cover 8x10, possibly 11x14, wide open.

Came mounted in an old dial-set Compur shutter which, by the serial number, dates to ~1914. Slightly oddball size on the shutter as well:both front and rear lens mounts have ~35mm openings--otherwise it appears to be a #1. F/stops are marked "4.5, 6.3, 9, 12.6, 18, 25, 36." No idea if it's original to lens.

Any help at all in figuring out what I've got here would be much appreciated. Thanks in advance

[Steven Tribe]

An older RR\Aplanat lens in a barrel (which, perhaps, had engraved details) has had it's lens cells moved over to "modern" shutter which was originally fitted with something like a 105mm Tessar. But lots of other possibilities!

Measure the effective focal length and the real aperture diameter at "F4.5" - then our guesses will improve in quality!

[Punkinhed7]

Focal length appears to be 170-180mm. When you say measure the "real aperture diameter at 4.5," what exactly do you mean/how would I go about doing that? Thanks again

[Punkinhed7]

Well, using a rough estimation/measurement/guess of the entrance pupil--simply measuring the diameter of the front element--gives an aperture of either ~7 or ~7.5, depending on whether I use 170mm or 180mm as the focal length.

I'm inclined to think the focal length is slightly closer to 170, just because I used a more precise method to come up with that number--though its entirely possible my measurements were a bit off, even then.

Also, the point where the aperture blades in the shutter coincide with the circumference of the rear lens element is exactly at the 6.8 mark on the scale, if that means anything.

[Steven Tribe]

The entrance pupil is slighty less than front lens diameter, so I am still thinking it is a RR (F.8 or thereabout) which has been transferred to an early Compur from a 6x9 F4.5 folder.

[Punkinhed7]

Would an RR made for 6x9 have that much coverage though?

[Punkinhed7]

entrance pupil is 24-24.5mm

[Steven Tribe]

Would an RR made for 6x9 have that much coverage though?

No.

What I am saying is that the lens is probably from a barrel RR/Aplanat that covered 1/2 plate, 5x7 or 13x18cm, but has mounted in a (later?) shutter that was aperture engraved for a 6x9cm folder with a F4.5 lens (Something like a Tessar 105mm).