When unpacking fall on a significant differences for Nikon. The lens is much more difficult - which is not a disadvantage for me - and makes a high quality impression. In addition (just a bag there) is provided a stable quiver as opposed to Nikon, which can be attached to the belt, so you do not have to carry around a whole equal Fototasche if you want to take only this lens as a second lens.
The first images showed that one certainly must first learn to take pictures with the lens and its image angle.
The autofocus will work on my Nikon quickly and reliably. The sharpness of the pictures is very good with a large aperture in the center, on the sides a little weaker but still good for me.
I have no meticulous series of tests carried out, but simply different motives (landscapes, architecture, people, dog) was added and found quickly, it makes a lot of fun with this lens capture subjects that one has been photographed with other lenses. You really discovered a whole new way.
The angle for landscapes is breathtaking. In architectural photography, it depends very much on the subject. But the distorted, falling lines make precisely the charm and I have no recordings "equalized" subsequently. Even reworking of photos is not as my world, but the recordings are what they are. I have even set two shots from the Frankfurt shopping center MyZeil. The already remarkable architecture obtained by the fisheye effect nor a special charm.
Conclusion: Taking pictures with the lens is fun - my previous experience with Sigma experienced a positive turn - I'd the lens at any time prefer the original Nikon.