Summary: Superb lens quality and good construction. However, after three years and just few times used (around 10 photo sessions), the SDM motor stopped. I had to send it to repair. Now I have to use it with the screw motor from the camera.
Excerpt: I'm normally a prime shooter, but this can make me leave more of them at home. The construction is first rate, including water resistance and that intangible quality of the shot is there. It is terrific as a portrait lens, and it is long enough to catch some action shots.
Pros: Consistent Output, Durable, Easily Interchangeable, Fast / accurate auto-focus, Nice Bokeh, Rugged, Strong Construction
Summary: I am a devoted Pentax (or whoever the company is now) customer and this is the lens that should have a free recall. but I'll get into this is a bit. Given the money this lens costs, I am sorry I ever bought it; yet, at any price, it is almost worthless.
Excerpt: I bought this lens when I bought my K-30 because it was on sale. Now I wish I would have gotten the body only because I don't use kit lenses anymore. Auto-focus is super quiet, pictures are great.
Pros: Consistent Output, Durable, Easily Interchangeable, Fast / accurate auto-focus, Rugged, Strong Construction
Summary: The DA* 50-135 is a fantastic lens in ALMOST every way. Until I ran into reliability issues with the silent focus motor on two separate copies forcing me to switch over to the discontinued but very similar Sigma 50-150 as my "go-to", I used the DA* 50-135 almost exclusively for portraits, artistic...
Excerpt: Since I've owned it for a couple of weeks only, can't really comment on the SDM durability, but for now it works fine. I haven't used other cameras with speedy lenses to compare, but for me, the AF speed is OK. Tracking AF feels kinda sluggish, though.
Pros: Accurate AF, Consistent Output, Durable, Nice Bokeh, Rugged, Strong Construction, Weather resistant