The lens is really sharp and is up to the standard that Olympus has already shown us with the M.Zuiko 12-40mm f/2.8. At the centre, we didn’t notice any decrease in sharpness throughout the entire zoom range and from f/2.8 up to f/5.6. If we start to pixel peep a little more, we can notice that at f/8 there is a slight loss in sharpness especially at the longer focal lengths. From f/16 up to f/22 there is some diffraction too, which is nothing out of the ordinary for a Micro Four Thirds lens.

http://www.mirrorlessons.com/2015/05/28/olympus-7-14-2-8-pro-review/

The Olympus 7-14mm f2.8 is another great lens for the Micro Four Thirds system. It manages to match or outperform the detail delivered by the already excellent Lumix G 7-14mm, while boasting an extra stop in aperture, the benefit of weather-sealing, and banishing its issues with flare.

http://www.cameralabs.com/reviews/Olympus_M_Zuiko_Digital_7-14mm_f2-8/

Image quality is excellent. Centre sharpness is very high throughout its focal length range, although the performance drops off a little at the edges, where you really need to stop down to at least f/4 to get acceptable results. Chromatic aberrations are well controlled, vignetting is present but not a real issue, and distortion is very well auto-corrected

http://www.photographyblog.com/reviews/olympus_m_zuiko_digital_ed_7_14mm_f_28_pro_review/

Manual

http://support.olympus.co.jp/jp/support/dlc/archive/man_mzded714f28.pdf

7mm

14mm

During testing this lens proved itself worthy, by delivering images with outstanding sharpness, whilst handling well and sporting a robust dust and moisture resistant construction.

http://www.ephotozine.com/article/olympus-m-zuiko-digital-ed-7-14mm-f-2-8-pro-review-27761

http://photo.yodobashi.com/gear/olympus/lens/mzuikoed714f28pro.html

http://admiringlight.com/blog/review-olympus-m-zuiko-7-14mm-f2-8-pro/

http://www.soundimageplus.com/soundimageplus/2015/11/15/the-olympus-mzuiko-7-14mm-f28-just-a-fast-lens-or-something-more

Can you mount a filter on it?

@mrbill

http://moelbar.com/filter-holder-olympus-m-zd-ed-7-14mm-f2-8-pro-lens/

http://www.imaging-resource.com/news/2016/04/16/olympus-7-14mm-f-2.8-pro-the-award-winning-wide-angle-oly-victory-lap