At 12mm there's significant falloff of sharpness from center to edges, but the corners are still better than I'd expect, and I'd rate them very good, even wide open. Even today one of the advantages M4/3 has over other mirrorless system is the prevalence of these high quality primes, whereas other systems tend to be loaded with slow consumer zooms (Canon EOS M, we're looking at you). Manual focusing is also available on this lens, both as full manual focus as well as full-time manual focus override while AF is enabled. Even corrected the lens has high amounts of vignetting in the corners at 12mm (over one stop wide open, two-thirds of a stop even at f/8). First is the zoom range, I’ve always shot 28mm, but having the 80mm possibility, sometimes I found myself exploring these focal lengths.

Fn button located about where you would usually have your thumb if you’re holding your left hand under the lens.

The results are very interesting – noticeably different than those of the rival Panasonic G X VARIO 12–35 mm f/2. This high-resolution, large-aperture zoom offers incredible versatility from wide angle to mid-range telephoto shots.

The lens is obviously going to perform better than the Oly 12-50mm anyway, it’s going to be at least as sharp, and most of the time a lot more so- I’ll be honest I only briefly checked sharpness comparisons online to make sure it was decent- it’s way better than the Oly 12-50 as you’d expect. Sharpness is good in the center, but the uncorrected RAW suffers from severe distortion and vignetting.The oddity is that the camera takes the modest amount of pin cushion distortion at marked 25mm focal length and changes it into a modest amount of barrel distortion!