Ok, at the risk of starting another horrendous OT flurry, here goes...
I finally got around to testing more lenses for radioactivity, and
here's the list. I only tested silvernoses, since the old lenses are
the most likely to use radioactive glass.
Lens Serial # Radioactive?
16/3.5 1010xx No
35/2.8 1099xx Yes. 1300 counts/min from the front, less from back.
50/1.8 1168xx No. M-System lens.
55/1.2 1099xx Yes. 80,000 counts/min from front or back.
75-150/4 1440xx No.
85/2 1028xx No.
100/2.8 1268xx No.
135/2.8 1359xx No.
300/4.5 1109xx Yes. 800 counts/min from the back, less from front.
With the early 50/1.4, this makes 4 known radioactive OM Zuikos. Note
that both the 35/2.8 and 300/4.5 are far less radioactive than the
55/1.2 (or 50/1.4). The amount of yellowing in these lenses is much
less than that of the 55/1.2, if even noticable. For reference, the
small calibration source of uranium 238 attached to the meter read
200,000 counts/minute, and the background reading was 100-200
counts/minute.
Happy holidays everyone!
Mark
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|