Hello everyone!I just bought the Tamron 24-70 VC last week ... and I had 17-55 till a few months ago for 3 years (I sold it in September 2012 to fund 5D MK III) ... as far as VC/IS is concerned IMO, Tamron 24-70 f/2.8 is more effective than Canon 17-55 f/2.8. I think it is just your copy that is at fault (if any).
I just rented a 24-70 f/2.8 VC from Lensrentals.com and have been using it to shoot around Disneyland. One thing I'm noticing, and wonder if it may be just this copy is that the VC/IS, isn't nearly as good as I had expected.
I have extensively used a 7D & 17-55 f/2.8 IS combo, and the IS on the 17-55 seems at least a full-stop equivalent better than the Tamron's VC, closer to 2 full stops. I could handhold 80% of my shots sharp on the 17-55 at 1/8, but I'm only hitting about 20% sharp with the 24-70 @ 1/20th.
Has anyone else been able to do a similar comparison?