8 out of 10 points and recommendedOptically excellent. Usable F2.8 and very good by F4. Light weight. Good value for the money.Inconsistent AF accuracy. No image stabilizing.
I bought my Tamron 28-75 F2.8 brand new a few years ago. The build quailty is acceptable for the price and the optic is excellent. I took many of my best photos with this lens I have a few Canon DSLR bodies and this lens works well most of the time. The image quality is almost as good as most Canon primes using in the 1.6 crop DSLRs as reviewed in the web.reviewed June 19th, 2010 (purchased for $300)
However, this lens has a fatal less known problem: inconsitent AF accuracy. For critical works, I must check every picture with maximum manification on the LCD for sure. Perhaps best with 10X on liveveiw.
I think Tamron had designed this lens with too short path in the focus ring (a trade off for the weak & noisy AF motor & gear?). The focus ring turns from 0.33m to infinity in less than 90 degree. This is difficult to acheive exact focus operation even by MF. The AF motor and gear are simply not precise enough for this Tamron.
I won't recommend this lens for the pros who need every photo counts without 2nd chance. I would prefer a slower AF operation to trade for accuracy.
If I'm a Tamron engineer, I will redesign this lens with ring type USM. Perhaps even add image stabilizing for better low light operation. Hopefully, with similar low price.