Had my Olympus 7-14 F2.8 Pro for about a year now, but this weekend I actually took it along with me for some serious landscape shooting. When I got back, I noticed that the edges of the frame were quite a bit less sharp than the centre (at 7mm), and that was at apertures of F5.6-F8 When I did a little more testing at home, I found that if I set the focus point on something right at the edge of the frame (and nearest the camera), rather than a further off centre point, then the edges (and centre) were much sharper and more in line with what I'd expect. For such a wide angle rectinunlar lens, I obviously don't expect the edges to be as sharp as the centre, but my initial images were actually quite soft at the edges (not just a little bit worse). This leads me to believe (rightly or wrongly) that the 7-14 F2.8 whilst a very sharp lens, does suffer from field curvature much more than the Panasonic 7-14 F4 that this replaced. Are my assumptions true and if so, what method do people use to ensure maximum DOF and sharpness across the frame please ?