Great lens when strong nerves and patience brings!

SIGMA 10-20mm f3.5 lens to HSM => 4 Stars
Pro:
- Top of field at f3.5 & 10mm - from mid to 2/3 edge. At f3.5 & 20mm top general. Best focus is at f8 10-20mm
- Top backlight insensitivity - Anyone who would like to integrate a direct sunlight as a style element in a photograph is, happy (especially compared to TOKINA, but also for NIKKOR)
- Price compared to Nikkor.

Con:
- The well-known blur at f3.5 10mm 90-100% & corners. Depending on the situation you have to sometimes because of blur in retrospect to 11..12mm cropping.

(Con before adjustment - I would never keep such => 1 star!):
- I can send me a total of 3 New Lenses of TechnikDirekt & Amazon. Both of my D5200, as well as on a borrowed D7100, were all 3 lenses const reproducible behavior during phase AF: Object Distance 50cm (about 12cm backfocus) 7m to infinity (back focus at infinity, that is, the image is completely out of focus!)

For SIGMA Support Germany & Austria -Representation => 2 stars:
- There will be replied in email inquiries only with the finished text blocks (partly specific enough). Somehow seems very ignorant!
- Despite indirect admission by SIGMA Support (quote from an e-mail response from SIGMA-DE: Provided that in a camera-lens combination, however, a fehlfokus shows experience shows does not help that lens to replace in the same type.) That can not interact phase AF moderate my aforementioned lens-body combinations from the factory, I do about 20 vers. Porto & pay my body for 2 weeks miteinschicken for adjustment! Despite upright Warranty & obvious Series deficiency
- The adjustment itself, but then works tadelos the 3rd lens!