Quality & Service Nightmare

I have long wondered how many stars should I give this lens. Technically, the lens is a 4 star deserves, if it is properly adjusted. But why only 2 stars are left, I will get to later. Unfortunately I have to write as a little more than usual to give a detailed justification of my evaluation.

I had bought the lens end of last year. Unfortunately I Beiging the mistake to make the purchase then while my camera was visiting the customer service. Sitting on tenterhooks, I had to wait until mid-January me until I got back revised and adjusted the camera. But what terror was offered to me when I installed the new Sigma to the bayonet of the camera. All images were focused wrong and showed an extreme front focus. A position of the lens to infinity was made not by AF. To exclude your own error or an error in the camera, I checked through my other lenses. None had such an erroneous focus on the contrary, I had the feeling that my other lenses met now better after the camera had been adjusted. So the lens again tested on a different camera. Again, the error with the wrong focus. Especially at full aperture, the focus was always wrong, very extreme part with a few meters fehlfokus. Even the HSM autofocus se, was conspicuously slow and reached nowhere near the speed of my Minolta kit lens with rack drive, let alone the speed of my Tamron. Then succeeded in times an image with manual focus, as it was discovered another shortcoming. Always the lower left edge was severely faded and blurred. Also stopping down did not help much here. Because, after more than 5 weeks after more exchange was possible, so I wrote to Sigma. You told me a repair time of 10 days, after which I sent away the lens immediately. When after 4 weeks still carried no emotion on the part of Sigma, I asked where my objective would remain. I received the friendly answer that, I would have misunderstood the mail. 10 days would repair only last if I did my camera with sending. Without camera repair would last 4 'weeks. However, this was definitely not in the first mail. Even after 5 weeks the camera was not there, but I finally received a message that could be interpreted almost as a repair confirmation. Only at the end I noticed that there was no confirmation of the repair, no, it was a request that I send my camera and image material must, so that the repair can be done. Even though I have to wonder today why Sigma is a customer camera needed to adjust a lens (neither Tamron nor Minolta needed suddenly the camera), so I sent my Dynax with gnashing teeth and pissed on the unnecessary waste of time on the way to Rödermark. Again went on for a week to the country and I could after the 6-week back and forth finally take my camera and lens in reception. Even if the repair ultimately vonstattenging successful, earned the Sigma service just one star, which is offered here as a minimum.

Because, yes, but one product well, the final evaluation is different. Visually, the Sigma much. It is qualitatively very well made and a sun visor is included. While the zoom and focus ring are translated very easily and steep, but extends no tube when you get close to an object and the stationary front lens (Internal Focusing) enables the use of polarizing filters Circular.
Regarding the image quality, so this was surprisingly good after the adjustment. Although the focus is not stunningly high as with a fixed focal length, but impressively well for a 175, - Euro Lens. Even the muddy spot in the left margin has disappeared and the lens records, dimmed by 1 EV, the edges and corners very sharp.
The coloring of the images is maintained relatively neutral with respect to the rel. warm Tamron lenses. Vignetting (vignette) are visible at maximum aperture, but not annoying for me and also easy to remove via Photoshop. Chromatic aberrations are primarily evident at the short end (18 to 24 mm). But even these are not serious and can be easily rectified.
Worse, it looks because of the distortion. Architecture photographer will definitely have no pleasure in this optics. On the short side there is a clear barrel shape. All straight lines look very severely bent. Less conspicuous, however, but the pincushion distortion at the long end at 50mm.
Autofocus itself is really very quiet, if you are used to pinion drive other Minolta lenses. The accuracy is given after the adjustment and almost every shot also sits. Fast criticized the AF was not even after the visit from Sigma. Here let me down the HSM significantly. Both at 18-50, as well as acquired at the same time 50-200 seem to need an eternity of focus. All other lenses of my hodgepodge with pinion drive (Tamron and Minolta) are noticeably faster.
The OS image stabilization is a fine thing for Sony / Minolta users, as it comes so sometimes the pleasure to enjoy a stabilized viewfinder. Effective, however, the in-camera sensor shift mechanism. While the lens about 1.5 to 2 aperture brings improvement, so do you manage with the Camera Anti-Shake 2.5 to 3.5 aperture. Nevertheless, the system of the lens works well and quietly. Therefore, and I will not criticize here.

Conclusion: After purchasing and without repair, the lens would not deserve a single star. Finally, all the photos were committee with AF. Following repair, the lens provided really good performance for the price. And even if there is no continuous panel, seeks to competing products with an aperture 2.8 in this price range in vain. Vignette and CAs are visible, but there is much more expensive products that produce worse aberrations. The focus really is better than you might think at that price. The build quality is top and on a professional level. Were it not for the virtually non-existent quality assurance and tiring AF, you could have given technically 4 stars. The lame HSM drive that failed quality assurance, slow customer service and the need to send their own camera let me come in the end only to lean 2 stars. Too bad, because the lens itself is not bad if you caught a good-aligned copy. And priced there is no alternative if you want to ascend a class from the kit lens.
Anyone who is not afraid to deal with the Sigma service or to swap until you caught a good lens, which can present this Shard really fond. Except for architectural photos, the glass is really worth the price. But if we consider all the trappings and the effort that you have to run to finally be able to take pictures with the Sigma, so can the, at least for me, only one conclusion. Never again Sigma - Sorry