[boosted03gti]

I plan on purchasing a fast telephoto lens within the 50-200mm range. Now i know the top 2 picks are the pentax 50-135 or the sigma 50-150. if i missing one please make a suggestion. my main concern is longevity. i have read several issues with sdm failing as well as focusing issues with the sigma so im on the fence. my priorities are:

1 - reliability
2 - iq

i dont want to spend 700-900 bucks to have a lens fail in a year or two. the sigma offers a 4 yr warranty and is a little cheaper so that a big plus but of course i want to make sure im getting the best iq for the money.

tia
jorge

I have 50-135.

Reliability: Well, my SDM doesn't work. It squeaks like a chipmunk. I use it as a manual focus 135 prime. If AF is important to you, I wouldn't buy one. Don't buy a second hand one at least. Buy a newer version perhaps, but I don't know if they are any different. BUT, I will say that DA*300's SDM with the newest firmware of K-7 is nothing like 50-135 (my copy anyway).

IQ: I would say that this is probably the sharpest zoom that I have owned. It rivals that of primes. Just superb. It is really a shame because, you know, SDM at the end of the day is a dud. DOn't plan on getting help from Pentax USA. They are really not "Pentax" people . . . . .