Very good choice for most photographic situations

A zoom lens is technically always a compromise. On the one hand an extreme focal length range from the 'real' wide-angle to telephoto is a desirable thing, because by the annoying changing lenses and the smuggling eliminates multiple glasses. On the other hand the problems and errors of optics with increasing zoom range to take sometimes extremely. Distortion, vignetting, chromatic aberration Sharpness Edge loss .... This can happen at very cheap super zooms to the relative uselessness.

That's why I prefer the use of at least two lenses (a wide / normal zoom and a telephoto zoom) always. So far I had for the lower range of focal lengths, the famous Pentax 18-55mm f Kitoptik 3.5 to 5.6. Even with this glass, I was very satisfied, at least on my IstDL because real weaknesses does not have this objective. It may not offer the very best in performance, but also does not suffer from pronounced weakness. After I bought more than twice as high resolution K20D very inexpensive here at Amazon (Marketplace), but grew the desire for something better.

After quite convincing Kitglas and also two other Pentax lenses from my small screen time that I use also to the digital cameras to the great satisfaction, the conviction grew that there is an original Pentax optics should be here again. My wish is 16-50mm / f2.8 been, because of the high light intensity and the water resistance the Pentax SMC DA. But a price of about 900 euros was me then but overkill. So remained as an alternative only 17-70 mm.

Now, after about four months where I could test the lens thoroughly, I realize it was the right decision. It offers in all areas of better performance than the mentioned Kitoptik. It is processed persuasive and it has a very fast and precise autofocus. The optical quality is over the entire focal length range good to very good. The distortions are very low, vignetting is virtually undetectable and it is sharp to the corners. Chromatic aberrations hardly occur, you have to compose the image extremely enlarge already to detect this effect in approach. Remuneration is typical Pentax perfectly glare in backlight hardly occur. The only considerable disadvantage, the ultrasonic focus does not work on my older IstDL.

In Detail:

+ Processing and feel reigns supreme
+ Practically impeccable optical performance no matter what focal length
+ Through quite fast lens speed of 1: 4
+ Fast and precise auto focus on my K20D
The lens still + manually when needed fast and accurate focusing
+ Supplied lens hood (tulip) with practical bayonet connection
+ The front lens and thus the filter thread does not rotate
+ Zoom range also covers the short telephoto range, ideal for portraits
To surpass + price / performance ratio hardly

- Compared to the 18 - 55 mm Kitglas quite large and heavy
- Ultrasonic autofocus works only on newer cameras, not to * istDx and not
K100 and K110.
- Not waterproof

Overall, I can recommend this lens with a clear conscience. Who wants to clearly improve compared to Kitoptik, obtained with this glass the right tool at a very reasonable price. Five Stars.

Greeting

RD