Supplement 06.06.2014
Have it now for six months and I'm still very happy with the Sigma 10-20 Had! Now the opportunity the Sigma 10-20 3.5 test. The 3.5 is about 60 grams heavier has 82mm diameter and is slightly longer. That was then but even the most serious differences. Otherwise the two are the same. They are like well-made! The design is the same! It's just a little larger and heavier. And so it is with the picture quality!
I could not detect differences between screen 4 and 10 in the image quality. Maybe you can see the on a 70d or 7d? But I would not bet on it. The only advantage is the continuous 3.5 Aperture .Davon but one should not expect too much because both lenses only dimmed full play to their strengths. To me it would be the 100 charge not worth it. Probably not even know 50.Ich also not what I might need a 3.5 aperture at an UWW. For highlighting UWW are hardly suitable for shooting in dark rooms and I would recommend a tripod or equal to a different lens, such as Tamron or Sigma 17-50 2.8!
For me, this is Sigma 10-20 4-5.6 still the good value for money !!!