Feels solidly built, sharp, focusing on static things in bright light felt relatively fast for 400mm lens, not spectacular fast, but OK, even with 1.4x extender on it.

I noticed is the contrast falls off in direct bright sunlight, this is true for most lenses, it makes a dull picture, other issue is focusing, now the lens focuses well, but if you are on auto shutter, well often you will be far below the correct shutter speed to get a nice crisp BIF photo, also at 800mm its hard to keep anything in frame, just practice, its a rewarding lens, for a good price and easy to carry and shoot, no tripod

In the lower light conditions there was limited aberration and the shots that were in focus were crisp!Focus:Result, 1 out of 3 shots were in focus using the automatic focus (testing both continuous and half-press

All three rings (aperture, zoom, focus) have good feel to them, like on all of Fuji lenses.