The discussions and reviews relevant to the advantages and disadvantages of zoom lenses (one at that with a very large focal length range) of course are well known to me. I shoot almost exclusively landscapes - as an amateur, but certainly with very high standards. Over the years my smuggling and the problem of contamination of the sensor at the permanent Objektivwechselei but has become increasingly troublesome. When I photographed analogy, I was advised as a coronation in Scotland an insect when changing lenses in the camera and there many days (alive!) Remained - what I did not realize until later when viewing the slides! Even a cart, with which I rel that. drew heavy equipment behind me, was not a solution, in part due to the significant shocks to the still very emfindlichen modern cameras (eg Nikon D300). That's why I repeatedly tried the latest zoom lenses, and then returned regularly without exception disappointed. Since I love to take pictures with long focal lengths, especially the regular loss of power at the telephoto end (visible) was disastrous. The more enthusiastic I am now of the Sigma 18-250 DC OS HSM, I now own for several months. The optical properties I find outstanding, especially in the telephoto range (at the D 300). I have compared in sorgfäligen series with the Nikkor 16-85 VR and Sigma 100-300 / 4 APO DG, both certainly not bad Objektive.Ich have in any area may find a worse performance, sometimes quite the opposite. I am very glad that I no permanent Objektivwechselei and with reasonable transportation dimensions (though of course always with tripod) can now be on the road without sacrificing quality. I highly recommend this beautiful lens highly enough to anyone. The popular term "Always top" has a high negative connotation. So I would say: I have the lens (practically) always on it. But is far better than an "Always top".