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Can anyone identify this lens set?

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#1 PhotoGazer

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Posted 04 November 2010 - 01:35 PM

I have this lens. It has an aperture diaphragm that goes from 7.2 to 20. It is in a heavy cast metal casing, and the optics appear to be coated. The focal length is around 19", and the optics diameter is about 110mm on one side and 100mm on the other. I have no idea which side is the front optic, or anything else about this hunk of lovely glass. Any help would be appreciated.

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#2 PhotoGazer

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Posted 04 November 2010 - 01:36 PM

Another look at this optic.

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  • 4163299-lens02.jpg


#3 PhotoGazer

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Posted 04 November 2010 - 01:37 PM

And one more view. Any help would be appreciated.

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#4 Lew Chilton

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Posted 04 November 2010 - 02:30 PM

An aerial camera lens? If it has coatings: post WW-II.
Does it have a manufacturer tag or part no. on it? Most of the old aerial camera lenses floating around originally had military applications and were war surplus. Many of these were adapted by amateur astrophotographers in the 1950s-60s.

#5 clintwhitman

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Posted 04 November 2010 - 07:58 PM

That would be my guess also Lew. The lens might be a great one. I think a bench test would be a good idea....

#6 Ken Launie

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Posted 05 November 2010 - 10:46 AM

It's not one I recognize but I agree that it's likely an aerial lens, and probably post-war (though Zeiss did coat many lenses in the 1930's). Unless it SAYS 19" focal length somewhere, it's quite likely that the effective focal length is somewhat longer, as many multi-element aerial lenses were of telephoto design to reduce the camera size. A "telephoto" lens by definition is a "lens whose focal length is greater than the back focal distance", ie one which is essentially optically compressed. It could act like a simpler-design 30" FL lens, for example. Many aerial lenses weren't color-corrected, though, and were used with B&W film and yellow or red filters.
--Ken Launie

#7 clintwhitman

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Posted 05 November 2010 - 11:33 AM

Ken woould the dial indicator for the apature size indicated the FL?
F 7.2 to F 20 ?
Clint

#8 PhotoGazer

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Posted 05 November 2010 - 04:06 PM

I guessed on the FL by seeing where an image came to focus behind the rearmost optical element, which was about 19 inches. I just set the optics outside and used a TV 40mm plossl in a 2" diagonal, and it appears that the distance to the center of the diagonal mirror to the rearmost element is about 9". The view appeared magnified, and the focus point was a mountaintop about 8 miles away. At this configuration, if I make a diagonal refractor, the tube will only be about 16 inches long.


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