Just received the book "EF LENS WORKS III, The Eyes of EOS" in the mail. I think it was a free gift from completing a survey a few months ago and forgot all about it. Great book if you want to know anything about Canon lenses and the physics of optics. Also doubles as a nice coffee table book of photos, and of the lenses that took the photos. I have three pages already page-marked in hopes my wife needs a Christmas hint from me. 
It was rather interesting to see that for the L lenses, out of the 10 to 17 lens elements only one or two are flourite or UD glass. The rest is optical glass. Guess a few pieces of flourite makes a difference. 
Here's a link to the book for those that haven't heard about it.
http://www.bhphotovideo.com …tails&Q=&sku=12218&is=REG
