i am in the market for a nice 70-200 lens and the final debate will be between the canon F4 and the sigma 70-200 2.8. i was actually all set on the sigma but i did some research on here and it seems like a lot of people are having issues with their copy. i see alot with focusing issues, wide opeen softness and even finish peeling off. now.
Define " A lot"...
5,10,15, 20....out of how many sales? I'm pretty much certain that the users who are happy with their particular lens (i don't use the term "copy") just get out there and use it, as opposed to pixel-peeping on a net forum and moaning about it.
As for "Lens tests" on printed focus sheets....err ok, if that's what floats your boat, but i never saw a Photographer sell a shot of a bar code to a magazine
The nature of sites like this (as good as POTN is) means that those with issues will always shout loudest. I've seen countless posts about problems with assorted Canon L's but very few people are diverted from L fever by those posts, are they?
Now, my 70-200 focusses fast enough to track Race cars & Military Jets, does not need a re-spray and if you want examples of how it performs wide open, here you go...
1# 70mm, 1/1600th @ f2.8.Centre Focus point was on the second girl in the line. This was a large, Fine JPEG straight from the camera using the parameter settings for the 20D suggested on the Sports Illustrated site.
2#. 103mm, 1/320th @ f2.8 in very poor light on a cold January day...
And now something stopped down a little. This was shot at Silverstone Circuit (Luffield Corner) and any of the Motorsports crowd on here will tell you 200mm is too short for there...so it's cropped quite a bit to make up for the lack of focal length. IMHO it's still pretty good...
200mm, 1/320th @ f5.6. Hand-held.
Now, just to give an example of the focus speed. I was heading for the car-park at Silverstone when these 2 cars were approaching...it was a "grabbed" shot and the camera locked on quick enough...
Hope that helps