So I've taken few shots just now, and I have puzzling results. I've shot few interior shots, and at f8 on a tripod/ES/remote shutter - image is sharp throughout the frame, incredible amounts of detail, much better results than same rooms with my Rokinon 14 2.8
But, I also drove around looking for shots outside (we had thick fog today, so a lot of cool shots were presenting themselves) - and I definitely see edge blurriness, even at f8. I was thinking - could it be due to sensor stabilization by any chance? Center looks sharp, but edges aren't. I'm trying to figure out if it's decentering (maybe my interior shots are sharp in corners because the of the working distance?) that shows at further distance? Unfortunately weather didn't allow me to setup a tripod somewhere and test it, although I was less worried about getting wet than with my Rokinon) Samples below (slightly processed and not in full res, but should be big enough to see edge detail). Hope someone can help me figure out if I got a good copy or a dud) I don't have enough experience with UWA's to decide I guess.
PS: It kind of seems that if I hold the camera almost perpendicular to ground, I don't have the edge/corner softness, but if I tilt it up/down, then I do, feels a bit like tilt-shift effect-ish, although of course not as extreme. Could I be because of the curved front element, and extremely wide angle?
Interior sample, on tripod, ES, remote control, f8 - corners/edges are sharp:
Room_201_1.jpg - Google Drive
Outdoors shot that shows the edge/corner softness - f8, hand-held, 1/8 with IBIS on, center seems sharp:
Fog4.jpg - Google Drive
Outdoors, f8, 1/10, hand-held, IBIS on, edge/corners seem sharp:
Fog2.jpg - Google Drive
Ourdoors, f8, 1/8, hand-held, IBIS on, right bottom corner and left upper corners are soft, rest seems sharp:
Fog6.jpg - Google Drive