Originally posted by JimD
I've got the Pentax and I'm very pleased with it but I have the chance of the Tamron for a very good price.
Has anyone had any experience with both and would the Tamron be much of an upgrade?
Obviously the Tamron is f2.8 and the Pentax is f4 but that aside is there any merit on splashing out? I've got a Pentax DA 12-24 so the slight difference at the shorter end doesn't worry me.
I have the 16-45. It is a relatively sharp lens even wide open. It is not pro glass but acceptable in most situations. I shoot nature shots with lots of trees and contrasty situations. I noticed that the 16-45 has all sorts of CA issues... Purple, green you name it. I was able to fix it in Photoshop but it is there. I am used to seeing purple fringing, even on my Limited lenses but green fringing I had never seen before.
I bought a 17-50 Tamron but ended up giving it to my brother to take pics of his kids. I purchased another Tamron from a PF member but it had this weird erratic aperture behavior. He took it back and sent it in for repair. I ran out of funds and did not buy it again. I did some test shots with the one I gave to my brother. It was a little soft at f2.8 but it sharpened up nicely from f4 on.
I tried the Sigma 17-50 f2.8 at a photo show. It was very sharp and it has a better built than the Tamron or the Pentax 16-45.
If you already have the Pentax 12-24, you have a much better lens than the 16-45 or the Tamron 17-50.