| I own the Tamron and have heard the Sigma 24-70 is a bit slower to focus only because it's a bit heavier and there's more glass/weight to move. Heard good things about the Sigma 28-70.
The Tamron is fast, sharp and great IQ. nothing at all to complain about this lens at all. I knew and owner that had this lens and the FA*28-70 Pentax and the only difference was the Tamron locked focus a little bit quicker (from one extreme to the other because it is heavier) and the Pentax had a little smoother bokeh. Both were generally equal in IQ and sharpness.
You might be hard pressed to find anyone that has had all 3 and compared them head to head. |