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Thread: Wollensak-Dumont CRO 75mm f2.8 Oscillo-Anastigmat?

  1. #1

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    Wollensak-Dumont CRO 75mm f2.8 Oscillo-Anastigmat?

    Anyone have any experience with this lens? Its in an Alphax heavy duty shutter, mechanism very slightly sticky and a full aperture range from f2.8 to f22, though goes a little further to around the f32 mark. Speeds seem sound enough for negatives. Anyone know the coverage? It seems to be almost 5x4. . .

  2. #2

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    Re: Wollensak-Dumont CRO 75mm f2.8 Oscillo-Anastigmat?

    It wilkl not cover 4x5. It was designed to be used to photograph oscilloscopes at very close range, a matter of images. It may cover 2.25" sq. at infinity.

  3. #3

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    Re: Wollensak-Dumont CRO 75mm f2.8 Oscillo-Anastigmat?

    Thanks Jim, not really worried about infinity coverage, more macro. Just need to quickly fab a lensboard and I'll try it out eventually (renovation work in a conservation area is a massive headache dealling with planners and building control. . .)

  4. #4

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    Re: Wollensak-Dumont CRO 75mm f2.8 Oscillo-Anastigmat?

    By all means try it out, but understand that in its intended application it didn't need high resolution, also that it is intended to image a curved surface (actually the inner surface of the front of a CRT) on a plane, so in general use it will have considerable curvature of field.

  5. #5
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    Re: Wollensak-Dumont CRO 75mm f2.8 Oscillo-Anastigmat?

    I bought one of these a few years ago, but not for the lens. I needed the Wollensak shutter for mounting a barrel lens. Very cheap way to get a good shutter, in my view.

    Keith

  6. #6
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    Re: Wollensak-Dumont CRO 75mm f2.8 Oscillo-Anastigmat?

    I should have added that before buying the lens and shutter I carefully checked the photos of the shutter I bought. Apparently, some of the shutters for these type lenses don't have mounting threads in the rear.

    Keith

  7. #7

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    Re: Wollensak-Dumont CRO 75mm f2.8 Oscillo-Anastigmat?

    Ta folks, once the weekend's over, hopefully I'll get a chance to experiment a wee bit. The shutter does have threads on the rear, and has a tube fixed to it that seems to reduce the image circle a wee bit. Not sure how much use the tube itself is so it may undergo a little 'surgery' so i can use the threaded part to secure to a lensboard.
    Alternativley who else here can say they have a loupe with an aperture range of f2.8 to f22, and speeds of T, B, 1/25, 1/50, and 1/100 :P

  8. #8

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    Re: Wollensak-Dumont CRO 75mm f2.8 Oscillo-Anastigmat?

    The shutter is a good one, but the lens is a paperweight, sorry to say. I bought one recently, for the shutter, out of curiosity I stuck the lens on some bellows on my NEX and it was awful, very soft, very glowy, didn't seem to be very highly corrected at all, or perhaps only corrected for green light as you get from an old oscilloscope?

  9. #9

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    Re: Wollensak-Dumont CRO 75mm f2.8 Oscillo-Anastigmat?

    Thanks Ian, rekon it's worth it for a few shots then. Have a baby graphic with some darkslides kicking about, so once the mess of renovations are over might chase down some X-ray film and cut it down. Soft and glowy might actually work for a small number of shots, plus the shutter just needs a wee bit of lubricant and that'll be the end of the stickyness (only really effects B and T slightly)

  10. #10

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    Re: Wollensak-Dumont CRO 75mm f2.8 Oscillo-Anastigmat?

    I think the Alphax is designed to run dry, so check if it should be lubed before you do, it might need cleaning instead. You could certainly use the lens, you might gt something nice and artistic, post the results when you do, I'm intrigued.

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