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150mm/4.5 Rodenstock Yasrex for XL.

 
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awk026



Joined: 22 Jul 2004
Posts: 1
Location: South Africa

PostPosted: Thu Jul 22, 2004 12:52 pm    Post subject: Reply with quote

I'm keen to know of anyone's experience/opinion of this lens, which was made for the Graflex XL series.
From what little info I've been able to find out to date, it's reputed to be extremly sharp, and is refered to as a "rare element" (or is that "rear" element?) lens. What exactly does that mean?
Further if anyone is able to give me an idea of what this lens would typically sell for I would be most grateful; is it particuarly hard to find?
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45PSS



Joined: 28 Sep 2001
Posts: 3219
Location: Mid Peninsula, Ca.

PostPosted: Thu Jul 22, 2004 7:54 pm    Post subject: Reply with quote

A rare element usually refers to RADIOACTIVE materials used in making the glass. Low level stuff, may fog film if left on a loaded camera for several hours, might cause a cancer if you carried it in your pocket 12-18/7.
To test for radioactivity sit suspect lens on an unexposed sheet of film for 24 hours then process as normal (keep film light safe). If a circle is present where the lens was it is radioactive.
Polaroid shet film is perfect for this test.

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t.r.sanford



Joined: 10 Nov 2003
Posts: 812
Location: East Coast (Long Island)

PostPosted: Fri Jul 23, 2004 1:24 pm    Post subject: Reply with quote

If memory serves, "rare earths" include nonradioactive materials like lanthanum and ytterbium. They can be added in small quantities to molten glass, changing the refractive index and so giving optical designers more options. It seems reasonable that Voigtlander's "Apo-Lanthar" was so called because lanthanum was used to dope the glass.

The "Ysarex" has an excellent reputation. Rodenstock makes good stuff.
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