Am quite excited about the lens and can see no weakness. For sports and stage photography, the focus range is super. However: Heavy piece. With stabilizer, a steady hand and breathing techniques are absolutely with 1/80 pixel sharp photos at full aperture even in low light conditions such as stage-pictures possible. Whether the same focus is also available in full-frame, I can not judge. The focal length scope including crop factor cause the everything that is broad in outstretched arm two fingers, Full Frame appears in the viewfinder and will be quickly reliable sharply with the very quiet autofocus. The stabilizer is booming while sometimes slightly audible. When the lens is inserted from 400mm to 100mm, smells like oil and technology, because air is pumped out. The other way round is to be sucked dust may. I think this can be minimized by good care and cleanliness after use. Will watch it and report.
