View Full Version : Bausch & Lomb BE4800 f/2.1 3.5 EF Projection Lens

17-Sep-2012, 17:26
Hi all,

I recently acquired a very inexpensive Bausch & Lomb projection lens. It's my intent to figure out a way to mount it to a 2x3 Speed Graphic to see if I can generate those magical swirlies that people have such strong and ambivalent opinions about.

The lens is marked "Bausch & Lomb Optical Co. Rochester, N.Y. U.S.A. BE4800 f/2.1, 3.5 in. E.F." The diameter of the rear element is 31.8mm, and the diameter of the front element is 42.6mm.

I believe that it only has two groups of lens elements, so I'm hoping that it's a petzval and not a triplet. Reflections I can see in the elements are bright, dim, dim ... I think?

The barrel feels like aluminum. The whole assembly feels a lot newer in my hand that it looked in the pictures. The finish is a nice textured bakelite or plastic.

There are slots for spanners on the front and rear of the lens, along with a single flathead screw. The whole rear of the lens is a screw mount with a 53.9mm (2.10 inch) maximum diameter. If the rear screw mount were removed, it looks like the outside diameter of the barrel surrounding the rear element would be 38.8mm (1.44 inch).

I may be able to remove the rear screw mount by futzing with the flathead, but I may be stuck with it. If I'm stuck with it, I'm guessing that there's no way to mount it to a piece of wood or aluminum that'd have the same dimensions of the (correct me if I'm wrong) 2.25" square original 2x3 lens board?

In sum:
1. Is this lens a petzval?
2. Does anyone know how to remove the rear screw mount from this lens?
3. If the rear screw mount can't be removed, is there a way to install this lens on a 2x3 speed graphic lens board?
4. Inexpensive digital calipers from Harbor Freight supply are a significant source of amusement.

Pictures follow.




17-Sep-2012, 20:17
to mount it try black foam core board and under cut the hole and screw it in and see what Happens