« on: October 06, 2014, 07:00:15 PM »
TBH the MKI is renowned for being a dubious lens and getting a good copy is key...Slight contradiction there...yes there are stellar copies of the MkI in existence, but tend to be rare as hens teeth. After five MkI's all of which were utterly hopeless and unable to be rectified by Canon, I was happy as can be with a great copy of the 24-105 f/4is which I got to see me through until the MkII was released. I didn't expect it to be so good. The 24-105 is a lot of photographers most used and favourite lens, so you could consider one of these. They are a true bargain.
The MKI is a stellar lens, but so is the Tamron. I chose the MKI because I like to stay in the Canon Camp.
Might be worth waiting and see what sigma do with the rumoured 24-70mm F2 IS
Sell your MK I and pick up a MK IIIf the budget allows this is the preferred route. My MkII is so good I've sold off all my primes in the 24-70 range.
Can't comment on the Tamron, but they do get good reviews.