Great results and favorable price

First, a few words about the quality of the lens itself. The build quality is top. Clean, precise and high quality built. Handling is relatively simple, there is only a fixed aperture (6.3) and a fixed focal length (500mm). The focus ring is balanced right and left in exactly the position you have just set. Still, he can rotate relatively easily. I feel sometimes set back really 35 years old, when I was working with a manual Mamiya ...
Today I use a Canon EOS 5D Mk.II, which provides me with the lens great results. At 400 ISO even freehand with min. 1/250 sec. Or faster, the pictures are really good! With tripod even at 100 or 200 ISO and longer exposure time. Clear, Sport or dynamic pictures are so simply not possible. But architecture, nature and even portraits go. In the latter case, the focus does indeed a positive effect, leading to very nice results. I will use the summer the lens also in New York City, for example, to photograph the Empire State Building to One World Trade Center (Freedom Tower) is over. The value for money is unbeatable for lenses of this type.

Addendum (08/15/2013):
Have repeatedly used in New York City the lens. Unfortunately, it was in a few days rather hazy. The images are compared with my Sigma and Tamron lenses rather pale. On a clear and sunny day, the images, however, are really good and differ only very slightly from my expensive lenses.

After intensive use my judgment is still: highly recommended!