Hi Ken, I've not used the 300/4 IS (but why should that stop me from commenting--it doesn't seem to stop anyone else!), but I will offer these remarks:
I never found the FD 300/4 (new) a convenient lens to carry; the EF 300/4L IS is about the same size but heavier at 1190g vs. 945g for the FD lens (in other words, the EF lens is about 25% heavier than the FD lens). I got good results with Canon's 1.4x extender on the FD 300/4 (non-L), and I expect results with the EF L lens and EF extender would be even better. The issue of whether the IS version is less sharp than the original is a contentious one, the heat seemingly based largely on subjective impressions. The Photodo results are interesting, but there's no way to know to what extent they are the result of sample-to-sample variations or, perhaps, an indication of poor quality control for the 300/4 IS. However, if your intent is to use the lens handheld, the issue of absolute sharpness may be irrelevant as camera shake would probably be more of an issue, in which case the benefits of IS might more than offset whatever you give up in pure optical performance (so long as your subject isn't moving). Not entirely tangential to your question, I might point out that the EF 200/2.8L II is quite a bit more compact and lighter (765g) than the 300/4 IS, and remains so even with the EF 1.4x extender attached. I can attest that (optically) the original 1.4x extender is virtually undectable when used on the 200/2.8, and even the original 2x extender gives quite good results. Of course, this combo may not give you the reach you want--you may even want to plump for the 400/5.6L if you need that much reach--but it may be worth at least some consideration. Regardless of what you finally choose, it is well worth a visit to www.keh.com, as they currently have several of each of these lenses in good used condition at attractive prices. Craig * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
