Hello:

I just bought (but haven't received via mail yet) 15+ front cells (apparently unused) for the Rodenstock-Ysarex 127 mm f/4.7 (Polaroid 110?, although they say Rodenstock-Ysarex) on them) lens.

If this is a tweaked Tessar, does anyone know if the front cell is (+) or (-) f.l.? And if it's a single element? (Tessar is 4 el., 3 group, so one has to be a 'doublet'.


These could be white elephants if they're negative. Maybe work as a 'Telek'-type teleconverter? If (+) I could use for homebrew lens experiments.

Oh, for other posters, regarding the radioactive Lanthanum glass reputation, in the Aero-Ektars (which are not Tessar-type, however) the radioactive cells are at the rear if used. They usually yellow over a couple decades too, and because the R-Y cells I bought are colorless, I'd assume they're not 'hot.

I will probably use a 4x5 CG of course for my experiments.

Thanks

Thanks

the front cell on my Y_R is slightly negative. Now I"m not sure how they mounted it, but with an old Xenar I had, you could remove the two pieces of glass and then the front on it's own was a nice 4x loupe. The rear is the cemented doublet.

RE: Lanthanum glass; the lanthanum is not the cause of the radiation in itself. The Aero Ektars had Thorium in the glass and that is a problem. It was always said to have been a mistake on Kodak's part but I have read study reports on this that state that Kodak's own documents say it was added intentionally.
Now, if you will excuse me, I will go sit in the closet and glow for a while ------

Oh, great, negative...I hope there are some scratched ones that need replacement somewhere in the world :eek:)

Glenn? from WY - I still want that bed rail...

Scrapin' my wallet (don't laugh)

Murray

I am figure the Rodenstock-Ysarex cell out, based on approx. f.l. of front meniscus, an dresult of cell + apparent f.l. of random lenses I have at home.

Front meniscus appears to be close to 50 mm or +20 diopters.

Combination of front meniscus and double concave (nearly plano-concave)2nd element is negative. The cell and a lens of approximately 111 mm or + 9 diopter had an apparent f.l. of about 8.25 inches or 210 mm or +4.75 diopters. This means DCV lens is
-24.2, cell is -4.2, and missing element(s) to give 127 mm f.l. or +7.87 diopters need to be +3.67 diopter or 272 mm.

I am doing to try to lengthen it a bit. The 111 mm/ 9+9 diopter lens I had was the back element of a Schneider Xenagon or Curtagon from a Kodak Retina Reflex that was screwed up. This will give me 210 mm roughly.

Above was inspired by lens equation discussion in Greene's "Primitive Photography...".

Murray

Read about <a href=http://medfmt.8k.com/mf/radioactive.html> Hot Lens here. </a>