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ausphoto
09-29-2010, 02:55 AM
;)
Well, having once been a German, it was/is my experience that Germans DO write their sevens with a horizontal bar mid-way down the stem, and most Germans would have a little ascender on their '1' and not just a straight stroke "|"...
Certainly the '7' was the rule ten or so years ago (to distinguish it from the '1'...) and this thing is not a new lens...so, I'd take that as a reasonable assumption..

But the clincher for me is that the measurements are Imperial and not Metric...

Q.G.
09-29-2010, 03:52 AM
An assumption that may appear reasonable. Yes. But appearances can, and will, be deceptive.
(Have a look at how sevens appear on Zeiss lenses, for instance.)
;)


Anyhow: the imperial measurements offer more 'solid' evidence.
Could still be, of course, that a lens maker normally using metric units supplied optics to be mounted inside units made by someone using imperial units.
;)

ausphoto
09-30-2010, 02:07 AM
Managed to design a quick and dirty lens mount an stick the lens on a tripod. That allowed me to estimate the focal length a bit better. Looks like that the effective focal length of the lens is 24 inches. This means, given the diameter of the first element, it's more likely to be an f5.6. Doesn't look as powerful as the aerial lenses should be...but have put out various feelers beyond APUG

michaelbsc
09-30-2010, 06:32 AM
Doesn't an aerial lens need to be wide field?

I don't really know much about aerial photography, but 24 inches onto a 10 piece of film doesn't seem very wide.

What am I missing?

Marco B
09-30-2010, 07:27 AM
Doesn't an aerial lens need to be wide field?

I don't really know much about aerial photography, but 24 inches onto a 10 piece of film doesn't seem very wide.

What am I missing?

Entirely depends on the flying height. "Normal" aerial photography can be done at modest heights and may use smaller focal lengths, but I remember reading a recent article about US spy plains flying at heights up to above 10 km, and they used cameras with focal lengths inbetween 20-40 inches if I remember it well...

Marco B
09-30-2010, 08:32 AM
One thing that bugs me about the "aerial" camera lens identification, is that the "mount" in the middle of the lens just contains 3 fragile bolts. Just imagine these being subject to the vibrations of air turbulence... Unless this lens was somehow securely "clamped" down in a structure we don't see, I can not imagine how it would hold.

And compare that with the many thread holes on this Fairchild aerial camera lens below (at least what they appear to be, I don't know much about these aerial cameras, maybe it is something different). I already see some 4 holes(?) for bolts this side of the lens, and I guess it is bolted down with 8 or 9?

But maybe someone else knows better how these lenses were fitted in the aerial cameras... :confused:

This is a lens made by Fairchild Space & Defense Systems:
http://www.aerialphotolab.com/images/Museum/Fairchild_Space_Defense_Lens.jpg

From this page:
http://www.aerialphotolab.com/apl_museum.htm

And here is an F56 aerial camera with 40 inch lens:

http://mysite.verizon.net/yenrav/20cms/f-565.jpg

From this page:
http://mysite.verizon.net/yenrav/20cms/cameras.htm


Managed to design a quick and dirty lens mount an stick the lens on a tripod. That allowed me to estimate the focal length a bit better. Looks like that the effective focal length of the lens is 24 inches. This means, given the diameter of the first element, it's more likely to be an f5.6. Doesn't look as powerful as the aerial lenses should be...but have put out various feelers beyond APUG

Last, according to this Camerapedia page (http://www.camerapedia.org/wiki/Fairchild), the K-17, K-18 and K-22 came in versions with 24 inch / F6 lens option. So your values seem anything but strange...

ausphoto
09-30-2010, 08:57 AM
Thanks for the link to arialphotolab..!

See here for lens mounted in makeshift bracket:
http://www.flickr.com/photos/heritagefutures/5038518501/

Marco B
09-30-2010, 09:33 AM
Here is what is apparently one of the camera systems used on the U-2 spy plane, with a rotating lens unit. The U-2 had a serious payload limit (see this Google Books link (http://books.google.com/books?id=uOcrDF0y-CAC&pg=PA54&lpg=PA54&dq=k-38+aerial+camera&source=bl&ots=78f1vILpR6&sig=4hNKFUUcHmXcNtcp87elpDP9Dro&hl=en&ei=1pKkTPSJNdDKswaIq9izCA&sa=X&oi=book_result&ct=result&resnum=8&sqi=2&ved=0CDoQ6AEwBw#v=onepage&q=k-38%20aerial%20camera&f=false)), so they had to adjust existing K38 cameras. Maybe that explains the "holes" in the lens? Simply safe weight wherever possible?

http://www.apug.org/forums/members/marco-b-albums-thread-pictures-picture27169-u-2-b-camera.png

And three other images of a different camera system that was definitely on the U-2. Unfortunately, the pictures are not clear enough to fully understand the lens/shutter assembly and how it was fitted to the rest of the camera body:

http://www.apug.org/forums/members/marco-b-albums-thread-pictures-picture27168-070711-f-1234p-016.jpg

http://www.apug.org/forums/members/marco-b-albums-thread-pictures-picture27170-070712-f-1234p-011.jpg

http://www.apug.org/forums/members/marco-b-albums-thread-pictures-picture27171-070711-f-1234p-012.jpg

From this page: http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=9169

Marco B
09-30-2010, 09:40 AM
Thanks for the link to arialphotolab..!

See here for lens mounted in makeshift bracket:
http://www.flickr.com/photos/heritagefutures/5038518501/

Wow, that really makes you appreciate the size of the beast! ;)

greybeard
10-04-2010, 03:32 PM
An intriguing thread.

One possibility that seems not to have been mentioned is that the holes were added for a special purpose, unrelated to the original application. In the 1950s there was a lot of military interest in rocketry and missilery, and not much on the market in the way of specialized tracking cameras. (There are historical pictures of tracking cameras built on antiaircraft gun mounts and the like.) The holes may have been put in simply to allow the lens to more rapidly equilibrate in temperature when exposed to cold (high altitude, perhaps, or actic conditions), or to prevent damage during rapid depressurization. And maybe it is one-of-a-kind because the idea turned out not to have been very good!

ausphoto
10-04-2010, 03:51 PM
intriguing ideas regarding the holes in the mount

AgX
10-04-2010, 05:10 PM
One possibility that seems not to have been mentioned is that the holes were added for a special purpose, unrelated to the original application.

Interesting idea. But in that case the lining of the holes would either be of blank metal or (re-)enamelled.

ausphoto
10-04-2010, 06:54 PM
only if it were a one-of-a-kind, which I don't think it is....still looking...