After upgrading to an EOS 5D my existing standard lens EF 24-85mm f4.5-5.6 showed it's faults. While it gave me superb results on my old 400D it was not up to the 5D. I bit the bullet and payed the price, the lens is amazing, even at f2.8 images are very sharp at the centre albeit with slightly soft edges, at f5.6 it's faultless, it is slightly bulky and I feel it would not suit a 350 or 400D body due to it's quite heavy weight. The best thing about it is the f2.8 aperture on my 5D it gives small depth of field which is great for portrait work and isolating subjects from the background. If you own a 30 5 or 1D you should own one of these lenses. The focusing is so fast it's often focused before I've realised. Test reports on the lens say it distorts at the wide and tele end well if it does I can't see it in photographs. One of the best buys I have ever made, after the 5D itself, 99% of all my wedding photography is carried out with the 5D the 24-70 and a 580EX.
I've been lugging around a number of lenses for a couple of years (EF17-40, EF28-135, EF 50 etc ) but this lens enables me to leave them at home and get really astounding pictures with this baby. Downside it's a little heavy but so were the others together. Strongly recommend
I have a Canon 40D and purchased this particular Canon EF 28-70mm f/2.8L USM lens for its clarity and brightness and the extra versatility offered by the easily composed out-of-focus background it provides. A great further feature is the special effects of its macro range. It is also completely compatible with my Speedlite 580 EXII flash unit. Altogether a neat purchase.
Great lens, this is definetly one of the best. Great optics smooth focussing. The lens is great with a full frame sensor but for those of you with a crop factor this lense has a great telephoto effect for use in the studio and outside.