tom_l4

<p>Perhaps I sent the wrong signals, so I'll be clear: I'm not worried about radioactivity from this lens. There are already plenty of other discussions online about that.<br /> <br />I found the topic interesting because I could not find much information about this online. One owner with access to a lot of FD-lenses reported an old copy as radioactive and a newer one as not. On a related note the initial version of the Minolta MC Rokkor 58mm 1:1.2 has a radioactive element, but the later two versions that share the optical design do not.<br /> <br />I did an initial check of my lens, and I saw nothing beyond background radiation.<br /></p>

<p>There are numerous sources online (including videos) showing that the 55mm Asph has radioactive glass. But I've also found two sources stating that their copies are not radioactive: <br /> <br />C. dePolo, this forum: <br /><a href="/canon-fd-camera-forum/00NufL?start=10%20">http://www.photo.net/canon-fd-camera-forum/00NufL?start=10 </a><br />Serial number 112XXX, production year 1977. <br /> <br />Ed Mika, maker of FD-EOS conversion kits: <br /><a href="http://www.canonrumors.com/forum/index.php?topic=5792.0%20">http://www.canonrumors.com/forum/index.php?topic=5792.0 </a><br />75XXX - radioactive. <br />126XXX - not radioactive. <br /> <br />My copy is in the 135XXX range, and I can see no classic yellow tint, except from the amber coating. The production code (U) indicates 1980 as production year. <br /> <br />I should obviously check my lens using a Geiger counter, but I don't have access to one right now. It would be nice to hear if anyone else knows more about this, and if two versions differ optically in any way. <br /> <br />Regards, <br />Tom</p>

<p>Thanks for the information.<br> I think drilling/machining holes is beyond my capabilities.<br> I'll give a 52mm rubber lens repair tool a shot first.</p>

<p>Hi. Does anyone know if the Canon nFD 24mm f2 front ring should be removed by unscrewing it, or if the correct way is to lever the ring off?<br> <br />According to this guide for the f2.8, the front ring should be removed by unscrewing it counter clockwise:<br /><a href="http://www.dpreview.com/forums/post/57208104">http://www.dpreview.com/forums/post/57208104</a><br /><br />According to this question, this may not be the case for the f2:<br /><a href="https://www.flickr.com/groups/24098559@N00/discuss/72157635788366405/">https://www.flickr.com/groups/24098559@N00/discuss/72157635788366405/</a><br /><br />The nFD 50 f1.4 front ring apperantly don't have threads: <br /><a href="http://www.gregpotter.net/canon-fd-50-14-disassembly.html">http://www.gregpotter.net/canon-fd-50-14-disassembly.html</a><br> <br />Any help appreciated.<br /><br /><br /></p>