Originally posted by superdavis Thanks, snake
I have also owned both - Tamron and Pentax and can share your feelings about Pentax. It the lens one wants to love, but to be honest - that is bit difficult. Tamron - I agree opticatly it is better and has less vignetting at 17mm, but I did not like the harsh AF sound it makes with the screw drive, so I thought I should trade in for 1mm, SDM and WR to Pentax. Since Pentax is gone/sold, I have
now dillema for me which way to go, but thanks for hinting back to Tamron. I'll consider that.
Superdavis
The sound I can't help with. Yeah, it might be a problem for some, not myself, but I can sympathize if it is.
Then the choices are narrow. Was going to suggest one of the tank-like Tokinas (which I lust after, myself), but they are SD and one of them starts at very nice f2.6 (ends at f-2.8), but not very wide on APS-c.
This leaves only two choices:
Sigma's present version and the new 18-35 (both if you want something fast). This is our unfortunate dilemma being on Pentax and the result of years of mismanagement and poor marketing.
The Sigma is a very good alternative to the Tamron, though I think the focusing is slower and slightly less accurate. The flare resistance and slightly less contrast is a strong factor to think of.
If you go between the Sigma and the Tamron, I don't think you'll go wrong with either. The Tamron can even be had used for peanuts. I got mine new, with a 5 year manufacturer's warranty, to boot.