« on: November 09, 2012, 11:30:09 AM »
i only rented a copy of the tamron for a weekend alongside the 24-70ii so my experience may not be as great as some, and since no one has hands on a 24-70 f4 the rest is speculation on my part. What I can tell you is that compared to your 28-135 you won't be disappointed with the tamron. Its sharper than any 24-70 f2.8 mark i I have ever used and it's $1000 cheaper than the 24-70ii. The 24-70ii is sharper across the range than the tamron, but I wouldn't call it twice as sharp which is what it should be for twice the price. I suspect the 24-70 f4 you are considering will be likely as sharp as the Tamron, but you lose the f2.8. AF does feel a tad bit slow when compared to the 24-70ii, and it does struggle a bit more in low light, but then again you have primes to cover that issue. I would say for a GP zoom it is probably the best bet right right now. You get the f2.8 advantage over the 24-105 and it has the IS advantage over the 24-70ii, and while canon says you can have a 24-70 f4 maybe by christmas I'm going to guess the normal canon production delays will end up tossing it into february.
Personally I am holding out for a price drop on the tammy to closer to $1100 before pulling the trigger. In the mean time I picked up a nice copy of a 24-105 on craigslist a few months back for a little less than $700 and if I ever want to sell it I won't lose much if any value. Heck if the 24-70 f4 is not that great I may even make a little money on that lens.