Info Wanted on Large "Infrared Imaging" Barrel Lens

[leighmarrin]

Just a few minutes before the Junque Shoppe closed, I stumbled upon a large barrel lens. The side of it was marked INFRARED IMAGING, one end labeled OBJECT--the other end labeled FRONT, and lots of numbers somewhat in the format of military contract numbers. No iris, no maker's name, no flange or external threads or other apparent way of mounting it, except inside a sleeve, I assume. Black finish, probably anodized.

It was heavy--about 8" long and perhaps 3.5" in diameter. Projecting the image of a lamp about 20 feet away onto my shirt, I'd guestimate its focal length to be about 7 to 9 inches. It was symmetrical--both ends identical in size.

Googling INFRARED IMAGING lenses, I can't find much info related to this lens--anyone have info? Wonder if it would put an interesting image on 4x5 or 5x7? (And hopefully more interesting than the 240mm Fuji-Xerox copy lens I have..) Were I to buy it, I'd have to rig up some fixture similar to a Speed Graphic/Aero-Ektar set-up, as it is large and heavy. Price is $75.

Any info appreciated. Thanks from Leigh M.

[Dr Klaus Schmitt]

If it is corrected for infrared, most likely it will not be of much use for visible and the lens design won't serve that properly. Could you show a picture of what's written on teh barrel, maybe it gives a bit more info I could decode (as I am into special lenses - see my site).

[wallrat]

I'm not sure how much this will help you but a search on the research side of Google Books (books.google.com) found a number of results. Maybe it will help or at least point you in the right direction:

https://www.google.com/search?q=INFR...&tbm=bks&tbo=1

[Amedeus]

I'm a bit puzzled ... the infra red lenses I own are all optimized for IR, this is ... there is no visible light coming through whatsoever ;-)

Can you post a picture ?

[leighmarrin]

Thanks for all the replies. The next time I'm in that junque shop I'll ask the owner if I can photograph it--Klaus, I'll try to get a digi-snap of what appear to be military contract numbers. I'll also bring along a small flashlight to try and read the reflections to hopefully figger out what lens formula it is.

Do IR lenses typically have "FRONT" and "OBJECT" written on opposite ends, as does this one?

Thanks from Leigh M.

[Sevo]

Do IR lenses typically have "FRONT" and "OBJECT" written on opposite ends, as does this one?

Asymmetric barrel lenses without other directional marks sometimes are labelled that way. But the mixture sounds odd - front/rear is common, subject/object is not that rare in the 19th century and on lenses for lab use. But given that a IR lens can hardly be more than 80 years old, I'd have expected subject/camera or subject/rear, if the makers chose to mix terminologies at all - "subject" is common, but the use of "object" in an optical context is pretty much restricted to microscopy and only lingers around in objective. It never made it into general language (where few are able to explain the difference between subject and object).

[Dr Klaus Schmitt]

To make things hopefully a bit more clear: infrared is not infrared i.e. there is near infrared (also written NIR) in the 750-120nm wavelength range (0.75 - 1.2mu) and there is far infraread which basically is heat waves in the 2-4mu and around 10 micron (mu) range. The former range calls for optical lenses most often also somewhat transmitting visible light (400-750nm), the latter calling for silicon or germanium lenses which opaque ("black") for visible light and have a blueish mirror like appearance.

This is an example of such a latter lens:



Thermal infrared sytems http://en.wikipedia.org/wiki/Infrared using such lenses are often called FLIR, see http://en.wikipedia.org/wiki/Forward_looking_infrared but are also used for inspecting heat leaks in houses, turbines etc. and for medical purposes (Thermography) to inspect for proper blood flow etc.

[leighmarrin]

Arghh... I went back to the store today, and my short term memory is WAY OFF... I took a photo of the lens and will post it later. Sorry about the misinformation! Here's some corrections and updates:

--Ends marked IMAGE and OBJECT

--Maker is INFRARED INDUSTRIES, INC., who has evidently made a lot of projection lenses.

--Contract numbers, I think: 81395 ASSY. 21006053-103

--Has about six small tapped holes on outside, presumably for mounting.

Will post photo of it soon. Sorry about the misinformation. --Leigh

[leighmarrin]

Apologies about not taking notes on my first visit to the junk store--it was just before closing time.

Today I used a little flashlight to try and read reflections--am certain it's not a petzval, and seems to have too many reflections to be a triplet. Past that, I'm not savvy enough to figure out the formula. It's quite heavy--even compared to the B&L Cinephor series. The red thing on the bottom is a rubbery lens cap.

Googling INFRARED INDUSTRIES INC. LENSES shows a couple on eBay that appear to be modified petzvals for projection similar to the later Cinephor lenses, but thus far I can't find anything that looks like this heavy beast.

I'll pass on buying it--it's just too heavy for my cameras. But thanks for any info: it's an interesting lens.

--Leigh M. in Santa Barbara, Calif.

[Struan Gray]

Google the 21006053. It has a DOD part number that identifies it as a 'recording lens assembly'. No clue if it's NIR+Visible or IR only, but it will focus light to some extent. Original price 16k USD (!).

The really interesting part is that it should not be available for sale - officially at end of use it should be mechanically damaged to the point that it cannot possibly be used, or sunk in the deep ocean. Someone didn't get the message.