<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>