First let me say that this review is written for my copy of the 24-70 f/2.8 - not my opinion of the lens in general. I have seen what a good copy of this lens can do, and it is amazing! A good copy of this lens is a solid "10"! Unfortunately, I fell victim to Canon's poor quality control that this lens is known for, and received a VERY POOR copy.
The first problem I noticed was with the zoom ring. It was very tight between 24-50mm with a grinding sound as it turned. Between 50-70mm there was almost no tension at all. The grinding eventually disappeared after working the zoom in and out a bunch of times, but the tension issue never improved. I wish I could say this was the only problem... but the real problem was image quality.
The images my 24-70 produced were just awful! My first thought was, "how did this lens leave the factory?”. I know things happen and no manufacturer is perfect, but there seems to be a "soft copy" theme for this lens... which is a real shame since this lens has so much potential. It is very disappointing to pay $1300 for an "L" lens only to have it blown away by my $150 plastic EF-S 18-55.
My second copy is on the way and I hope it is a good one… Am I buying a lens or playing the lottery??? Good luck to anyone trying to find a good copy of this lens. It will be worth it once you find one - just be ready to return a lens or two.
P.S. – Don’t rely on Canon’s website for accurate reviews. I wrote a review on the Canon website two weeks ago describing the problems with the lens I received (following all the rules – no prices, etc.). I was not bashing the lens or the company; in fact I was praising what a great lens it is if you get a good copy. I also described the tests / comparisons I ran while trying to get an acceptable image. Since my review, two other “5 star” reviews have been posted, but mine has not. It looks like Canon is trying to hide their poor quality control on the EF 24-70 f/2.8!