Image courtesy: Photozone.
The Olympus M.Zuiko ED 40-150mm f/2.8 PRO is, mostly, a highly desirable lens – except for one bug. On the positive side, it is very good if not excellent in the primary image quality metrics. It is very sharp across the focal length range including some greatness in the middle portion. Vignetting and distortions are very low. One the downside, the quality of the bokeh (out-of-focus blur) can be disappointing – not in all scenes but busy backgrounds are clearly not the lens’ best friends.
Olympus M.Zuiko ED 40-150mm f/2.8 PRO is directly competing with Panasonic’s Lumix G X 35-100mm f/2.8 Power OIS. Obviously the Olympus has the bigger range (and as such also a bigger size/weight) and is somewhat sharper whereas the Panasonic has clearly the better bokeh plus an image stabilizer. Both are very good really.