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lens from Xray
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PostPosted: Sat Mar 22, 2014 5:49 pm    Post subject: lens from Xray Reply with quote
Hi! what do you think about this lens? Apparently this is lens from an old Xray machine. But I dont know company .Sad . Maybe you know. Want to sell but don't know the true cost of this stuff.




http://forum.mflenses.com/userpix/20143/big_7988_DSC00254_2.jpg

Last edited by Glacue on Sat Mar 22, 2014 5:55 pm; edited 1 time in total


PostPosted: Sat Mar 22, 2014 5:55 pm    Post subject: Re: lens from Xray Reply with quote
Glacue wrote:
Hi! what do you think about this lens? Apparently this is lens from an old Xray machine. But I dont know company .Sad . Maybe you know. Want to sell but don't know the true cost of this stuff.





PostPosted: Sat Mar 22, 2014 8:18 pm    Post subject: Reply with quote
Cost (new price once) is one thing, current market price is another. Xray lenses are extremely hard to use as they were computed that the film they were projecting to basically touched the rear lens element, which today makes them nearly impossible to use (except for very closeup macro). I have many such lenses but hardly can use them.


PostPosted: Sun Mar 23, 2014 1:56 am    Post subject: Reply with quote
It would probably be awesome at burning ants or starting fires by sunlight. Smile


PostPosted: Sun Mar 23, 2014 2:00 am    Post subject: Reply with quote
Yep, or stopping doors from getting thrown close by wind Wink


PostPosted: Sun Mar 23, 2014 3:11 pm    Post subject: Reply with quote
Impressive lens!


PostPosted: Sun Mar 23, 2014 3:51 pm    Post subject: Reply with quote
It will be a good candidate for competition like the lens with largest front element within 135mm. Smile


PostPosted: Sun Mar 23, 2014 4:46 pm    Post subject: Reply with quote
Interested to know what it weighs??


PostPosted: Sun Mar 23, 2014 5:06 pm    Post subject: Reply with quote
In his book The Photographic Lens (1968, Focal Press, London, New York. Originally published as Das Photo Objektiv, 1956, Friedr. Vieweg & Sohn Verlag, Braunschweig), Hans Martin Brandt explains that lenses such as Rodenstock's XR Heligons and TV Heligons were used in pairs for

Quote:
presentation of the image formed on an X-ray amplifier tube screen to a larger audience via a television system. Conventional optical systems cannot satisfactorily project these images onto the photo cathode of a television picture tube and special optical designs are required for this purpose. …

While it would go beyond our scope to go into this specific application in exhaustive detail, the optical transmission of an anode image to a television system requires so-called tandem lenses. These are a combination of two lenses optimally corrected for infinity. They are arranged in such a way that the anode image is in the focal plane of the first lens, while the photo cathode tube of the television camera tube is in the focal plane of the second lens. …

In the first place this relay optical system must have the largest possible aperture. On the other hand geometric image corrections must be brought to an optimum …

Rodenstock suggest a number of their lenses as suitable for such tandem combinations. Recommended systems for the lens facing the X-ray image tube are the 100 mm Kinemar f/1.5, the 75 mm XR Heligon f/1.1 or the 50 mm XR Heligon f/0.75. The second lens for projection onto the final image plane can be a 32 mm Heligon f/1.3 (for 16 mm narrow gauge cine), the 70 mm Heligon f/1.4 (for standard 35 mm cine cameras) or the 50 mm TV Heligon f/0.75 for Vidicon cameras.


PostPosted: Sun Mar 23, 2014 7:43 pm    Post subject: Reply with quote
kryss wrote:
Interested to know what it weighs??

About 10 kg


PostPosted: Mon Mar 24, 2014 2:17 pm    Post subject: Reply with quote
Would have to obtain mortgage to pay for shipping.


PostPosted: Mon Mar 24, 2014 5:26 pm    Post subject: Reply with quote
Depending on construction of lens, sometimes it is possible to shift internal elements to increase the register distance, usually at cost of speed and getting some magnification increase.


PostPosted: Mon Mar 24, 2014 6:00 pm    Post subject: Reply with quote
...and at cost of sharpness/image definition as it is no longer as computed.


PostPosted: Tue Mar 25, 2014 7:04 am    Post subject: Reply with quote
As said, it depends.

It's all on your knowledge.

If you move a lens from a group, sure you will get sharpness decrease, CA, vignetting and so on. But if you move complete group, you might only marginal decrease in image quality, but up to 20-30% increase in register distance, which often might be the key factor for lens adaptation.
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