I’m not a fan of telephoto zooms in general. The good ones are big, heavy, and expensive. The cheap, small, light ones just aren’t very good. In my opinion, Pentax excels when it goes after high optical quality, high build quality, and small size at the cost of weight and sale price. That’s the formula for the Limiteds and the reason I bought a Pentax in the first place.
Even though I rarely enjoy using telephoto zooms, I miss not having one. I live in constant fear that I’ll see a gazelle 100 meters away and I’ll be unable to fill the frame with its face. I had the Tamron 70-300 for A-mount, and I had a lot of fun with it. Probably the best lens of the type for the money. Tamron sells the same lens for K-mount, but I wanted something smaller and weather proofier.
I didn’t feel a need for a K-mount telephoto zoom for a while because I got a manual focus Pentax M 135mm f/3.5 essentially for free. That lens doesn’t have the best reputation among Pentaxians, but I found it to be a gem. Small, fast enough, and pretty good optically. Manual focusing on a DSLR is not my favorite, but I managed some nice shots with the lens and got used to its quality for my telephoto shots. Instead of honing my skills with a quality lens, I decided I had to have a lens with autofocus and weather proofing.
Enter the SMC Pentax blah blah 50-200 blah blah WR. It’s small, light, inexpensive, zoomy, autofocussy and weather proof. It’s also built well for a modern lens. I like everything about it except for the image quality. The image quality isn’t bad at all, but it’s nothing special. Furthermore, with all the convenience features like zoominess and autofocosity, I get lazy and take boring photos. Other photographers most certainly make fantastic photos with this lens, but I struggle with it.
Maybe that says more about me than about the lens.