Help with Wollensak USAF Lens

Punkinhed7 · Jan 17, 2016

I picked up this lens recently and am having a bit of trouble digging up any information on it. I realize that this technically may not be the correct forum to ask about this particular lens but I figured the LF users might have a bit more experience trying to use unusual old lenses so I was hoping that someone here might be able to help shed some light. Please forgive me for the hasty iphone snaps.

The lens itself measures approximately 8 inches long with a diameter of ~ 4 inches. The rear element/housing is ~3/4" diameter.

Given that it is marked USAF (and the wide FOV) I assumed it may have been used in some aerial application but if I'm way off base, please let me know. Google searches haven't yielded much information and the only reference to something similar that I've been able to find was for a 142 degree projection lens that was used in artillery/arms training.

I was unable to get it to focus on my Cambo SC through the entire range of extension -- minimum using bag bellows.

Assuming the ' EFL : 0.147" ' indicates effective focal length (3.7338mm) I used the AFOV formula:

to calculate the horizontal dimension of the intended film format and came up with 21.687mm, which seems like a mighty small image circle for such a beast of a lens. If I've misapplied this formula, used the wrong value for AFOV, etc. please correct me. This was the actual calculation:

As for the notation: ' FD: 1.102" ' is this an indication of focal distance...ie. the lens should be 1.102" from the film plane for focusing? If so, that might explain my trouble so far in getting it to focus.

Also, marked aperture click stops are 1.5, 2, 2.8, 4, 5.6, 8, 11, 16

Anyways, I appreciate any and all comments y'all might have as to the origins, intended use and, most of all, possible future uses for this creature.

Thanks in advance

Photos of the lens:

John Koehrer · Jan 17, 2016

SWAG here. Considering the size of the mount & short fl could be for a movie camera maybe?

Said it was a SWAG didn't I?

shutterfinger · Jan 17, 2016

Telescope lens? Aircraft camera lens?

Prof_Pixel · Jan 17, 2016

Punkinhed7 said:
Google searches haven't yielded much information and the only reference to something similar that I've been able to find was for a 142 degree projection lens that was used in artillery/arms training.

That looks to be quite likely

Dan Fromm · Jan 17, 2016

FD means flange distance. And that's why you can't focus it on y'r SC.

The shortest lens in my 1967 list of lenses used by USAF is a .92"/5 Tropel that covers 2.25" x 2.25". Lenses with small coverage include a 105"/36 AO mirror lens that covers 0.6" and a 20"/4 Perkin-Elmer mirror lens that covers 20 mm. All of this proves nothing about your Wolly.

My best guess is that it was for an airborne cine camera. I could well be badly mistaken. Pacific Optical made some very short lenses in c-mount for USAF, that may be a hint. I think, memory could be failing, that the shortest was 1.5 mm.

Jim Jones · Jan 17, 2016

Considering the aperture range, it could be for an aerial reconnaissance movie camera or more likely for high speed movie recording of something like rocket takeoffs. Amateur astronomers might find it useful with digital sensors for photographing wide sections of the sky.

Punkinhed7 · Jan 17, 2016

Considering the Flange distance, might this be adaptable to an m43 system?

Punkinhed7 · Jan 17, 2016

Also, any ideas on the distinctive mount/rear of the lens--with the section cut out diagonally from the base? And what about those chrome circles on the barrel (there's one on either side of the big plate)?

Thanks for all the help guys!

shutterfinger · Jan 17, 2016

any ideas on the distinctive mount/rear of the lens-

Precise mounting on the camera/telescope/optical device it is for.

AgX · Jan 17, 2016

But that chamfer is unique.

Paul Howell · Jan 18, 2016

AgX said:
But that chamfer is unique.

My best guess is that the lens was custom made for the AF for use on a particular custom made recon camera or tracking camera. Might be a one of a kind.

AgX · Jan 18, 2016

My guess too. Except that for tracking cameras one hardly would use a 142° lens. It is numbered as #74. Likely not a single piece.
Yesterday I already was looking in vain for an apt camera.

jimgalli · Jan 26, 2016

Might get it checked to see if it's an emitter. We were cleaning shelves last year and found a gov't wolly that was quite 'hot'. Nope, don't know what this is.

AgX · Jan 27, 2016

"Emmitter" and "hot" in this case would mean that it would emit ionizing radiation, due to radioactive ingrediant in the glass. Yes, likely something to check.

frobozz · Jan 27, 2016

Sure looks like it would mount right up to my 16mm 200fps Traid camera:

http://backglass.org/duncan/traid_200v/

Same basic specs (142 degree angle of view, f/1.5 max aperture). not sure why the design is different. Maybe because it doesn't have the goofy light array built in?

Here is some footage I shot with it:

http://backglass.org/duncan/slomo/RocketLow2.mov

Duncan

AgX · Jan 27, 2016

I'm completely puzzled. I know some technical/scientifical cameras. But I never saw lenses with built in incandescant lamps. I mean for warming an optical system one likely would use non-light-emitting heaters. At least not when they emit into the optics. The fact that the lamps are seperately wired is puzzling too.

And what are those two tube connectors for?

And that chamfer?

And what is that pane/lens with that hole about?

And that black spot in the image center?

AgX · Jan 27, 2016

Anyway, a good toy for the boy...

frobozz · Jan 27, 2016

AgX said:
I'm completely puzzled. I know some technical/scientifical cameras. But I never saw lenses with built in incandescant lamps. I mean for warming an optical system one likely would use non-light-emitting heaters. At least not when they emit into the optics. The fact that the lamps are seperately wired is puzzling too.

And what are those two tube connectors for?

And that chamfer?

And what is that pane/lens with that hole about?

And that black spot in the image center?

As near as I can dope out, the plastic pane with the hole in it (set in the tube behind the lens, but in front of the lamps) is for the lamps to reflect in, which would allow them to appear in the black area of the frame outside of the image circle. I have a much newer, fancier 16mm high speed camera (10,000fps!!) that has "timing LEDs" that can be triggered externally or set to blink at a certain rate, and they put red dots in the rebate area of the film, which is the same idea. This allows you to synchronize an external event, or a known timebase, with the images on the film.... perhaps in case you don't trust the camera speed settings and want to have a hard and fast indication of timing to correlate with the images on the film, or if you want to mark the film at the precise moment that some external event occurs. With the 10 independently controllable lamps, you could even do multiple things like this independently. (The camera with the timing LEDs only has right and left LEDS, so only 2 things you can mark independently.)

The black spot in the center is the hole in that plastic pane! I do not have any idea at all why they did that. Maybe to mark the exact center of the image?

I do not know what the tube connectors are for. Maybe for pressure or humidity control under severe conditions?

The chamfer does not look absolutely necessary to make the lens mount to this camera. Maybe it just helps the people assembling it get it in the correct orientation? Or maybe it is needed on some other camera application, not this one?

Duncan

AgX · Jan 27, 2016

Time indicators... I could have thought oft that...
But still puzzling is that the lamps are visible through the front lens, which may make them reflect into the filmed image of the outside scene too.

Anyway, thank you for unveiling this lens' enigma for most part.

AgX · Jan 27, 2016

That chamfer may facilitate to mount the lens on cameras like the Arriflex 16 with their mirror-shutters rotating at 45°, their shutter casings protruding

frobozz · Jan 27, 2016

AgX said:
Time indicators... I could have thought oft that...
But still puzzling is that the lamps are visible through the front lens, which may make them reflect into the filmed image of the outside scene too.

Anyway, thank you for unveiling this lens' enigma for most part.

The light from those lamps is starting as nearly a point source, and then being spread out across 142 degrees outside the lens - I don't think they will be putting much illumination on whatever is being filmed! Especially because you would normally only light one or two at a time.

Duncan

AgX · Jan 27, 2016

I knew my wording was bad, I already corrected it, to no avail... What I meant was that if one can see the lamps from the outside of the front lens, their light may be reflected from the rearsides of the front elements back into the lens, especially affecting the central image.

frobozz · Jan 27, 2016

AgX said:
I knew my wording was bad, I already corrected it, to no avail... What I meant was that if one can see the lamps from the outside of the front lens, their light may be reflected from the rearsides of the front elements back into the lens, especially affecting the central image.

I believe that is why they use a flat piece of plastic to reflect it back, rather than letting it bounce back off of the real lens elements. Note also the "hood" on the lamp assembly, to make sure no light spills over into the real image coming in through the lens.

Duncan

jimgalli · Jan 27, 2016

Timing lamps are usually inside the camera underneath the film platten blinking through slits onto the film. I've seen reticles that were lit. They burn a cross hatch into the film for data reduction.

frobozz · Jan 27, 2016

jimgalli said:
Timing lamps are usually inside the camera underneath the film platten blinking through slits onto the film. I've seen reticles that were lit. They burn a cross hatch into the film for data reduction.

Absolutely the way it's done on my Photec rotating prism camera that's a decade or two newer than the Traid. I don't know if it's because there's something different about the lens or the film transport (regular old claw mechanism running its little heart out!) that requires it be done this way, or because Traid was jamming together a mechanism and lens originally designed for other purposes, but if those aren't timing lights I can't think of any possible reason for them to be there, or for that plastic disc to be there.

Duncan

Help with Wollensak USAF Lens

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