The lens is different from the previous positive and negative:
+ Significantly better sharpness, especially in the corners. The lens is sharper than the old at stop 11 at maximum aperture in the corners.
+ Much better color drawing, the old one was yellowish, especially in the middle
+ Better handling
- Distortion (had barrel-shaped, the old almost no) more than the old lens
- Chromatic aberration visible, but especially for the focal length ok.
The failure of the new can be in Lightroom correct well, the lens is therefore to use professionally (which I have done with the old, however).
The vignetting is naturally strong, so you should stop down.
Who has no full-format and also do not want to buy, should look at the 8-16mm, which is comparable with the quality and the same angle of view on a APS-C also provides alternative).
A novice is not to be recommended to work with such an extreme focal length, because you have to deal with such a vast field of view, so as not to be disappointed by the results. Who, however, covered 17-200mm and knows what he wants to do with it, getting a good lens at a reasonable price.
