Help Identifying Big Old Lens

[Punkinhed7]

Picked this lens up recently because, well, I was impressed by its size. Measures about about 4 inches long, 3.5 inch diameter across the front and 2.75 inches diameter across the rear. Weighs 2lbs 14 ounces, so pretty hefty.

My assumption was that it was a process lens of some sort but it seems to have been pulled out of whatever casing/camera that once held it and that may have displayed the identifying information

The serial number “EM7976” is engraved on the front middle and rear sections—is that a 1943 CAMEROSITY code or something else? Additionally the rear has “BF123.05” or “BF12305” engraved as well.

Counting at least 9 reflections when looking down in to it, but I could be off.

The threaded ring above the plumbers tape rotates and activates a 15-bladed aperture with 6 click stops.

There are also bubbles in at least the front element, and at least one of the elements seems to have some thorium-related yellowing.

Seems to be a pretty fast lens given that it projects a pretty strong image, even in a well-lit room.


Anyways, thanks in advance. Any and all help/information would be greatly appreciated.

 

[shutterfinger]

Air bubbles are a sign of high quality glass from the day, more modern techniques of glass making eliminated them. They do not degrade image quality.
As for the numbers someone has scribed them into the barrel finish therefore they are questionable.
Aircraft camera lens?

 

[AgX]

BF123.05 could mean back focus 123.05mm .

 

[Ed Sawyer]

It is a 178mm aero ektar.

 

[Punkinhed7]

It is a 178mm aero ektar.

From the Kodak serial number I had considered that as a possibility. Any idea why it wouldn’t have the bezel ring/any of the other normal identifying markings?

 

[shutterfinger]

The way the parts are scribed I will speculate it was disassembled on someones work/optical bench, partially reassembled, awaiting remounting, passed away, clueless estate person put the assembled parts up for sale and trashed the rest or similar.
Theory #2: surplus from the back up bench at the repair depot.

 

[AgX]

It is a 178mm aero ektar.

Which means that likely I am right.

 

[Ed Sawyer]

They are all scribed that way from the factory. The extra parts are mostly useless. I take the filter holder off mine, it serves no purpose and is huge. I usually leave the aperture markings on the ring on but on one of mine I took it off since I mounted the lens behind the lensboard, and drilled/tapped the aperture ring to use as a mount. So, not all that unusual.

 

[jimgalli]

It is a 178mm aero ektar.

I concur. Had them before that looked just like that. Probably result of being built into a total package for the airplane that included a shutter assy and weighed about 38 pounds. When the lens itself is extricated this is what's left.