Chris: Very solid lens! The Pentax 50-135mm f/2.8 is a great performer. I rented this lens for a wedding and it was on my Pentax K-5 90% of the time. Its focal length is very useful for both portraits and long range shooting. The 9 bladed aperture creates beautiful Bokeh and is also great in low light. The Autofocus (SDM) is dead silent, the only thing people will hear is your shutter. The zoom ring is silky smooth and is easy to control. However, the focus ring felt a bit rough whether in auto or manual focus. Continuing on focus, the focus is very accurate on this lens but a tad slow. Since I wasn't shooting sports, it wasn't a problem at all. The lens is big, rugged, and weather sealed, which is just how I like my lenses. The overall weight of the lens felt great with the battery grip on my K-5. Overall, excellent lens! Wish I didn't have to send it back!