After a while of thinking and weighing up between the 300 f/4 and the 100-400 before the rebate for them ends on the 31st of Dec, i think the more versatile 100-400 is probably a better buy for my needs.
One thing i haven't heard much about is the performance of the 100-400 on full frame cameras, most of the online reviews are done on a 350D. I've looked in the achive thread but couldn't find any shots which said they were on a 5D (or 1Ds), that's not to say they aren't there but many don't have the exif intact or the poster didn't state the camera used.
Could any owners of a 5D or 1Ds and a 100-400 let me know what it's like on a full frame wide open, vignetting, edge sharpness or anything else you'd like to add 
Cheers, Col






