How do you plan to use the lens?
I just received a 60-250 and it is an amazing lens. It produces extremely sharp, contrasty pictures through its entire zoom and aperture ranges.
I bought three Tamron 70-200 F2.8s before buying the Pentax. The first Tamron was decentered, on the second one the aperture would randomly stick wide open, and the third one was decentered. If one of the three lenses was useable, I certainly would have kept it. The one with the sticking aperture did not have a centering problem and it was an amazingly sharp, contrasty lens with almost no CA. I just got tired of boxing them up and sending them back. The focusing is by the camera body and it is very fast and accurate. The focusing also works well in low light, but it is noisy.
The Pentax is a very solidly built, high quality lens. It showed no signs of decentering. I like the fact that it is very compact at 60mm (but heavy!) I can fit it (just barely) in my camera bag. It gets positively huge at 250mm - it is longer than my DA* 300mm. It is not an internal zoom like the Tamron. It weighs about the same as the Tamron, but the Tamron is F2.8 and a full frame lens. The focusing on the Pentax is virtually silent, but not particularly fast (at least on a K20D).
One big gripe I have about the Pentax is that it does not appear to actually be 250mm. I know that this is hard to believe, but when I set my target distance at 15' the Pentax seems to be more like 200mm. I need to do more testing. I don't see how it could be a problem with just my sample.
I would not get both the 50-135 and the Tamron, because the 60-250 Pentax covers this range nicely with one lens and it is cheaper. Even though it is an F4, it works indoors nicely (on a K20D). Here is a candid picture I took at 250mm F4 indoors - it is very sharp.
Originally posted by malakola cost isn't a concern. what's your choose ? why?
1. FA* 80-200
2. DA* 60-250
3. DA* 50-135+ Tamron 70-200/2.8