It is a comparably compact lens with a metal mount and a silent, fast autofocus.

Being a small telephoto lens with a focal length equivalent of 75mm one of its purposes is portrait shots.

Wide open the lens is rather soft but stopping down to f/5.6 yields very sharp results.

That way portraits shot wide open render soft with a very nice bokeh.

[3] Distortion is very low and vignetting negligible, but the culprit of this lens is chromatic aberration which is very strong wide open and becomes acceptable only by stopping down towards f/5.6.