The lens, have been waiting for many long

To make it short: The Sigma 17-50 2.8 OS HSM, I finally found the lens that I've been looking for. It offers 17mm wide angle, which is sufficient for my purposes (a special wide-angle lens I've sold again, because it was most of the time at home in the closet). At 50mm, although the image effect is at the long end already concluded but to take a few steps on the subject often anyway good. In addition to the practical focal range covered mainly two other advantages to the weight: the integrated luminosity of 2.8 and the OS (Optical Image Stabilizer). While the former allows shutter speeds of moving subjects or the charming play with the depth of field, the OS offers for static subjects. Thus most photographic everyday situations are covered. The excellent all-round capability of this lens is rounded off thanks to Sigma's HSM drive through the fast and unerring AF, which also convinces with low contrast.

Among the externals:

The lens is so big and heavy as the Sigma 17-70 OS that I had roughly. Other than that, however, it is equipped with a made of cheap plastic lens hood and lens caps as cheap-looking. Because obviously has cutting back what is a damning indictment for a lens in this price range. The lens hood also snapped a little and the front lens cap is attached loosely. Such a modest quality is not yet come across me in any other Sigma lens, and I have some of them. Apart from this corresponds the perceived quality of the OS 17-70, with which there is also something else in common: In both the focus ring rotates during focusing, which is annoying if you happen to just the hand at this point. Then I could do without.

For image quality:

The lens delivers even at full aperture at all focal lengths (!) Razor-sharp images. The colors are warm and vivid, contrast is good. CA (chromatic aberrations and fringing) hardly play a role, even under extreme backlight situations they occur only in a very limited extent. Very good is generally the behavior in backlight - a point where this lens stands out clearly from other fast lenses that produce often overexposed when shooting against the light, low contrast and washed-out images. Not so this lens, thereby allowing attractive light shenanigans!

Especially with 17mm a certain distortion is detected that can be disturbing in some images. Since it sometimes helps to curtail the images a little, as long as the objective is not yet supported in software correction as PTLens. By the way, there are few lenses that do not or hardly ever experienced such. As some fixed focal lengths. For a zoom lens is the Sigma 17-50 so determined nothing to reproach in this regard.

My Conclusion:

+ Practical zoom range that makes the lens an all-rounder
+ Excellent sharpness even at full aperture and across the entire zoom range
+ Rich colors (Sigma-typical warm) and good contrast
+ Good bokeh (background blur effect image)
+ Acceptable distortion
+ CAs very well controlled
+ No slump in backlit scenes like other fast lenses
+ Very good OS

- Cheap hood and lens cap

+ - Focus ring rotates with when focusing

Due to the achievable high image quality and the facilities with the active OS I forgive five points, despite the inferior lens hood and lens cap. The price goes for what is offered in order.

The background of this purchasing decision:

I was long looking for a so-called. Always plan, so a lens that is versatile and the photographic covers basic needs. I started with the 18-55 of Nikon, which was there with my D40. After purchasing a D90 was the 18-105 VR Nikon. The change to the D300s brought at the same time moving to the Sigma 17-70 OS with it. This suited my requirements almost, but not quite. Therefore, the search went on for some time on - a hand-selling Tamron 28-75 2.8 was eliminated due to the slow and uncertain AF, as a further letdown proved the Sigma purchased from Amazon 24-70 2.8 HSM (see my review it). Fortunately, the return was seamless.
At the end of the search, we went to the decision between the new Tamron 17-50 VC 2.8 and the even newer Sigma 17-50 2.8 OS. My choice fell directly to the Sigma lens, Tamron because I was suspect with the AF problems, over which should be read in many places and I had experienced at 28-75 even.