NikonGear'23
Gear Talk => Lens Talk => Topic started by: John Geerts on November 12, 2016, 23:56:00
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Has any one perhaps experience with this Schneider-Kreuznach Xenoplan 23mm f/1.4 lens.? It's a CCTV lens, whatever that may be. It is in the C-mount, and the front of the lens is a 52mm thread, so it could be reversed.
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"CCTV" = Close Circuit Tele Vision
They usually have a C-mount and their image circle is small. Even on a 1 Nikon CX camera some of these lenses cannot fill the entire frame, small as it is.
TV lenses are not optimised for image sharpness in the manner we expect from a photographic lens. They literally "focus" (sic) on the bigger detail.
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Ha, thanks, Bjørn. Probably used for surveillance camera's then. So no real use for 'normal' photography, I guess.
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For experimentation's sake, how feasible is it to enlarge the image circle of a lens like this to cover a 35mm frame by means of a lens relay system of some sort?
If possible what might the setup look like?
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Obviously it is possible to make a relay system in order to increase image circle. However, it will probably be quite bulky as one might need at least 5X linear (25X planar) magnification of detail, and a mediocre resolving CCTV lens will at the final stage deliver mostly mush. If that is the desired outcome, put one any native lens on your camera and defocus it. Much easier and results will be comparable :D
Another point often overlooked, is what the focal length implies when you change format. From a 35mm/FX perspective, "23 mm" sound like a wide-angle lens, but that is a fallacious assumption. On the contrary, this is probably a "tele" equivalent lens on its native format and no relay system can change that behaviour.
In my experiments, I usually started with a high-definition cine lens made for 8mm format. You might also use 16 mm film cine lenses, but then the focal lengths tend to be fairly long in absolute terms and the step towards the FX format is too small as it were.
A system used for years is this based on an old Canon 6.5 mm cine lens with excellent quality for its age. The photo below depict the lens and relay system from one of the first builds (for DX). The current one is redesigned to allow use on an FX camera, in combination with a ring flash. The unit also got its by now mandatory CPU implant. Any how, this goes to show there are lots of parts involved in building even this kind of simple system. In place of the small and neat Macro-Nikkor used here, one could of course use a reversed 20-24 mm lens, but the entire rig would be much bigger and bulkier.
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I tried the relay system using a c-mount Canon TV-16 25mm f1.4 lens and Olympus Zuiko MC Macro 38mm f3.5 as a relay lens on Sony NEX-5R (APS-C mirrorless camera).
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Bjørn, thank you for the insight.
I have a few smaller format lenses like these I've always been curious about experimenting with so thought I'd ask.
I suspect for the lenses I have it would not be worth the effort.
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Don't misunderstand me: experimentation is of course OK. However, don't set expectations of the outcome too high.
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Thanks for your question Charlie and for your extensive explanation, Bjørn. I must have somewere a few adapters to make a kind of setup and shall perform a low expectation-experiment ;)