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

[DKirk]

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. . .

[Jim Noel]

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.

[DKirk]

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. . .)

[Dan Fromm]

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.

[Keith Fleming]

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

[Keith Fleming]

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

[DKirk]

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

[Ian Greenhalgh]

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?

[DKirk]

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)

[Ian Greenhalgh]

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. :)

[Leigh]

Oscilloscope lenses are not "optimized" for any range of reproduction ratios.
They're designed for one specific ratio (1:1), and that's all. If they work at any other, that's OK.

They have no chromatic correction because they worked with monochromatic light (green, occasionally blue).
Also, they're generally uncoated.

- Leigh

[Ian Greenhalgh]

I've had 5 or 6, made by Wollensak, Dallmeyer, Mamiya and a couple of others, all coated.

[DKirk]

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. :)

Was thinking along the lines of some teflon dry lube, I'll have a go at using it in a bit (the saga of being told one shade of paint can't be used in a conservation area, yet another shade that looks almost exactly the same can. . . the joy of renovations :P )

[DKirk]

They have no chromatic correction because they worked with monochromatic light (green, occasionally blue).
Also, they're generally uncoated.

- Leigh

All part of the fun then. Plus another 'excuse' to try x-ray film. . .