Sharpness at 150mm

For these tests, the Olympus M.ZUIKO Digital 40-150mm f/2.8 ED Pro lens was attached to an Olympus E-M5 body, which in turn was mounted on a sturdy tripod. The self-timer was activated. The 100% crops represent about 1/400th of the total frame area.

The full frame at 150mm

At the 150mm end of the zoom range, we find that wide-open sharpness is good, but there is a marked improvement upon stopping down to f/4, which is the sweet spot. Quality loss resulting from diffraction becomes obvious from f11 onward.

Aperture	Centre Crop	Edge Crop
f/2.8
f/4
f/5.6
f/8
f/11
f/16
f/22