Graflex.org

[headlessdrifter]

Hey everyone,

I have recently came across a Rodenstock XR-Heligon 68mm f1
Lens as far as I know its an x-ray lens and appears to be a bayonet mount, but it crossed my mind it might be worth a try putting on my 3x4 RB series B,
It is worth a mention i have no knowledge of adapting things like this, and hoping it fits right in.
Its also worth noting that i haven't purchased this lens yet.

Please any help would be greatly appreciated

Thanks, headlessdrifter

[Dan Fromm]

Don't. The lens is too short to focus at a useful lens on a 3x4 Graflex.

Here's an explanation of its intended use:

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:

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.”

[headlessdrifter]

Hey Dan,

Sorry for the late reply.
I see so the film would have to be near touching for the lens to be of any use,
I have also seen in a previous post on were the diagonal length across the film plane and a bit equals to the shortest possible focal length for the lens to project,
so, the shortest lens would roughly be 140mm without optical manipulation

correct me if I'm wrong

Cheer's headlessdrifter

[Dan Fromm]

Sorry, I don't understand your question. So I'll answer the question I think you should have asked. Feel free to tell me that I guessed wrong.

The shortest focal length (lens of normal construction, not retrofocus) that will focus to infinity on a 3x4 RB Ser. B depends a little on the lens' design, but the key constraint is that the rear of the lens has to clear the mirror when the mirror goes up.