View Full Version : Magic Lantern Projector Lenses

21-Jul-2013, 22:35
Anyone know about this monster? Couldn't find much about it searching. It's a Bausch & Lomb Balopticon Type 41-23-82. It has a U.S.N. (Navy) serial tag as well.

The light comes on, but not the blower, the bulb rear reflector is losing a lot of silvering. There is a wood slide holder/magazine, and an adjustable wood/metal plate holder that fits in the bottom. Any use for this machine aside from its lenses (assuming I have no lantern slides)?


From a distance, I thought it was a Big Bertha. I got it for $65.

The big lens says 18" E.F. and looks to have 3 element pairs. It is 4" diameter, and the barrel is 7.5" tall. It seems pretty clean, and would be even more should it be taken apart and cleaned.

The small one says Sunray Wollensak 4" Focus Back. The front element comes off, and the long steel tube screws apart to reveal a rear element.

Any info is appreciated, especially on the 18" lens. Is it a Petzval? Is it f/4.5? Coverage? It's too big for my iris clamp, how to mount it?

I would use it hopefully for 8x10. Would using its "turret" help reduce required bellows draw? How about screwing the turret onto a lens board?


Steven Tribe
22-Jul-2013, 01:19
Balopticon is one of the later types - and quite common.
It is a multi-tasking apparatus which, I think, works as both a slide projector and a episcope.
Most later models of this type had Cooke triplet rather than Petzval (only 3 lenses instead of 4!).
Using the turret would reduce bellows draw - BUT put increasing torque on the front standard.
I suppose Overhead Projectors will become an ebay item too - now that Presentation software has taken over the Educational visual market.

Tim Meisburger
22-Jul-2013, 05:59
Yes, overhead projectors are a good source of fast triplets.

22-Jul-2013, 07:18
The 18" lens came apart pretty easily. The back screws out to reveal one rear element on top of another separated by a spacer, and a further spacer toward the front with another element ahead. The elements cleaned up nicely. It's surprising how simple these things are, no cementing just elements and spacers.

So does it sound like a Cooke design? Any familiarity with the coverage and speed (f/4.5?), I guess I could figure out with some testing?

Any use for the 4" Sunray? Is it a Petzval design?

Did I get a good deal :D ???

Dan Dozer
22-Jul-2013, 13:03
While the focal length of the smaller lens may not work for you as is (depending on the size film you work with), try taking it apart and only using a part of the lens assembly. I do this with several of my old "projector" lenses and get very unique looks. Note that the focal length of only a part of the 4" lens may be much larger. I have a lens that is about a 4" with a small image circle, but the two halves by themselves work out at about 7" and 12", and both cover well on my 8 x 10 camera.

19-Mar-2014, 12:05
I finally got around to mounting the 18" lens, turret to 8" Deardorff board, unfortunately I couldn't get it to focus very sharp.

The turret allows for fine focusing of the lens, though I'm not sure it's needed, because I can also focus by moving the rear standard back and forth; the normal way to focus for my camera. The turret does help for mounting this lens to a board, however.

It seems to only focus in the extreme center, and not very sharply there, and pretty much out of focus everywhere else. It never seems to be fully in focus, even in the center. I have plenty of bellows, meaning when it comes into focus (not very sharply), if I keep focusing in that direction, it goes out of focus again.

I wonder if I'm missing something... or is this lens just not very sharp? Might incorrect assembly (after cleaning) be responsible? I was pretty careful.

The projector also has a smaller lens that produces a much sharper image (of a light bulb projected on the wall) when holding it in front of a lamp at its (much shorter) focal length.


20-Mar-2014, 06:01
The 18" lens came apart pretty easily. The back screws out to reveal one rear element on top of another separated by a spacer, ...Is it a Petzval design?

Did I get a good deal :D ???

It sounds like a petzval to me, two close together in the rear, with a metal shim holding them apart. You're problem with sharpness could be the way the rear is set up. It's supposed to be the thin edged one to the very rear. It will have a surface that is more flat than the other. Face flat towards the rear. Then "nest" the other lens on top, with the spacer. The two more severely curved surfaces together, facing.

30-May-2014, 17:04
Apparently it's a triplet (Tessar type). It was assembled incorrectly and now focuses! A lens expert friend sorted it out for me today. He thought it would likely be highly uncorrected. I shot 2 sheets of HP5+ in my living room this afternoon and should have something to post here soon. Seems to have coverage for 8x10. I misspoke earlier, I believe the middle element is cemented while the front and rear are not.

31-May-2014, 06:10
Here's one of the exposures, not the greatest, but the lens does focus!

Was back lit and I was trying to flash meter with a Packard shutter that has a sync cable - I set the meter to 1/30th, f/4, 400asa (box speed), and turned down the flash a bit based on the reading my L-358 gives for percent of flash to ambient light, it said 60%, so I tried to compensate for the 40% ambient by turning down the strobe a bit (e.g. 40%) - is that the idea? The subject was underexposed, not sure if it was due to the back lighting or my metering technique? Maybe I turned the flash down too much? I was guesstimating 40% ... The lens is supposed to be more like f/4.5 - but that didn't seem to play a part. I had my thumb over the metal hole in the shutter bulb.

I played with curves and levels to make the image usable.


Deardorff 8x10 Portrait camera, 18" E.F. Magic Lantern f/4.6 Tessar type lens, HP5+ developed in Rodinal (slightly higher concentration to 1:100), 12.8 mins in Beseler print drum with motor base, and scanned on the glass of Epson 4990.