I want to let everyone know about the high quality of service that I recently received from Canon Canada. I had to send my 24-70 2.8 in for a cleaning and calibration. There were a few specs of dust inside the lens. As well, the lens has never focused sharply at F2.8. I've always believed that I had been stuck with the much talked about "Soft Copy" of this lens. For years now, images at F2.8 were horribly OOF with terrible CA.
Well, my lens was with Canon Canada for about 6 weeks and I just picked it up today from Vistek. I went home and immediately did focus checks and micro calibration with my 1Ds3 and 7D. The difference in sharpness and focus prior and after servicing is night-and-day. I can say that I'm the proud owner of an ULTRA SHARP 24-70 2.8L lens... finally. My 24-70 lens went from terrible to awesome. Canon also did an amazing job cleaning the lens. I finally believe those owners who claim that the 24-70 is amazing lens.
I bought the lens in 2009 and the warranty had ran out since. Canon charged me $300 for "Cleaning, Centering, and Calibration". The awesome results are well worth the money if you ever suspect your lens of failing on any of the 3C's. Thank you Canon Canada!!!