Originally posted by brosen
I know that there has been some issues with the SDM system, but I will be purchasing them with my American Express card and they automatically offer one additional year of warranty after the Pentax (1 year) warranty has expired, so I will be covered for 2 years.
If I were you I would get an additional 7 year warranty from Mack. I think either Adorama or B/H sells it also. A 7 year warranty cost me under 50 dollars about 2 years ago for one lens [50-135]. At that time the lens was on sale for $799 also. I think it was around Thanksgiving. So watch the deals...And yes, the 50-135 is worth it.
Of course, I can't vouch for Mack warranties but there have been some discussions on this forum on it and they are not any better or worse than other such companies.
I have rented the 16-50 a couple of times, its big and heavy and not as good as the 50-135. Plus 2 sdm lenses was not comforting to have even with extended warranty. I looked at my shooting style and settled on the Tamron 28-75 instead as I shoot more people than landscapes. If you dont need the WR and need a faster lens to replace the kit lens range, the tamron 17-50 is well rated, while the new sigma 17-50 is also supposed to be pretty good.
I think the 50-135 will not diappoint you. As for the 16-50, why not rent it from cameralensrentals.com and see for yourself before you buy it?