Review by Klaus Schroiff, published July 2007

Introduction

The first striking feature of the DA 50-200mm is its size. Normally you would expect a tele lens to be fairly big and massive but the Pentax lens is a tiny being and not much bigger than the standard kit zoom. Despite the very low price tag the build quality of the lens is surprisingly decent. Naturally the outer construction is still based on lots of plastics but its quality is quite fine with relatively tight gap tolerances and there's even a metal mount. Unlike most kit lenses from other manufacturers the DA 50-200m ED does also features a usable, dedicated focus ring. Both the zoom and focus ring operate smooth. As you can see below the lens extends significantly when zooming towards the long end of the zoom range. There're two inner tubes ("duo cam") although the innermost one is only used by the focusing system. The front element does not rotate so using a polarizer is no problem.

The lens has no internal AF motor and relies on a slotted drive screw operated by the camera. As a result AF operation will generate a moderate degree of noise. The AF speed is reasonably fast although a little unsure at times and it's fairly accurate on the K10D. Thanks to a "Quick-Shift Focus System" manual focusing is instantly possible once the AF has achieved focus - this works very well and noiseless.