Does the 28-80/2.8-4 L use special glass?

<p>Just bought one of these on eBay and I'm trying to find out if the lens uses Aspherical, Florite or UD elements in its construction? Information for this old lens is hard to find.</p>

<p>My 1992 printing of Canon Lens Works says it has two ground and polished aspherical elements. Based on the diagram they appear to be the first and last elements.</p>

<p>Canon museum entry does not have as much detail, but here's the link.</p>

<p>http://www.canon.com/camera-museum/lens/ef/data/standard_zoom/ef_28~80_28~4l_usm.html</p>

<p>I believe all 'L' branded lenses contain at least one aspherical or fluorite element.</p>

<p>Enjoy your purchase! I like this lens but they are getting old and I've had or or two fail with a broken USM motor, which means neither autofocus nor manual focus work. If someone else has one with the opposite fault (working focus but broken aperture diaphragm) let me know and we can perhaps Frankenstein together one working lens.</p>

<p>One tip you may find useful is to set 'back button focus' on the camera body, so that the shutter button no longer engages autofocus. This will let you have full time manual focusing on this older lens.</p>

<p>Thanks for all of the information. I use and 5D and 1Ds, can these bodies be set up for "back button focus"?</p>

<p>With the 1Ds it's a custom function called something like "shutter release / AE lock". There are various choices and some of them mean that you must press the * button to engage autofocus. This is something you'll have to try to see if you like it in general; if you do, then it makes working with these older USM lenses a bit easier since you will be able to move the focus ring manually and autofocus as you choose without flicking the AF/MF switch.</p>

<p>I expect there is an equivalent custom function on the 5D.</p>

<p>It has aspheric elements but no fluorite or ultra-low dispersion (UD or super UD) glass.</p>

<p>Why do you care? If it takes great photos why worry?</p>

<p>For what it's worth to the OP I have a 28-80 2.8-4L EOS lens (circa 1992) which was my main taking lens for 35mm film for at least the next 15 years. Compared to my other non-L FD lenses I can testify that the clarity, openness of shadows and overall warmth of my Kodachrome slides was, WAS, noticeable.<br>

I haven't had a chance to do any comparisons on a digital sensor but am eager to try.</p>