I know there are lots of threads on de-fishing the Sammy 7.5, but I couldn't find one that looked at the IQ of defished images that have been cropped to match equivalent rectilinear lenses. So, I thought I'd do a few experiments - nothing too rigorous, but I did draw some conclusions from it, so thought I'd post it for anyone else who's interested. The Objective To see how corner resolution is effected when Sammy 7.5mm FE images are de-fished to a rectilinear projection and then cropped to suit equivalent rectilinear lenses. Setup I used an E-M5 mounted on a tripod and took a shot of the inside of my conservatory on a sunny winter's day (excuse the mess!!). I took shots at f5.6 with the Sammy and the Oly 9-18 @ 9mm for comparison. The focus point was on the far wall, a distance of approx 4m away. I then defished the Sammy image using a Rokinon-specific profile in Lightroom that I was created by user "kenw" on DPR. The profiles can be found on this thread: http://www.dpreview.com/forums/post/40689446 Aside from de-fishing, the Sammy image has a minor WB change to match the Oly shot and a -0.25EV correction (again, to match the Oly lens). Other than that, there are no other changes in LR. Original Images Oly 9-18. 1/350th @f5.6 Sammy 7.5. 1/500th @f5.6 Defished and Cropped Images I then defished and cropped the Sammy image to various fields of view as follows: 9mm (approx 90 degrees horizontal FOV): 7mm (approx 105 degrees horizontal FOV): 6mm (approx 115 degrees horizontal FOV): The focal length equivalences are fairly approximate since the actual FOV will depend on the exact mathematical projection in use - and rectilinear lenses at these focal lengths will not be perfect projections. However, I think it's close enough for a quick comparison. Note that the uncropped horizontal FOV of the Sammy lens is about 132 degrees, but I didn't examine that since the defishing results in extremely wide images with significant smearing at the edges that is beyond what most would consider acceptable. Comparison of corner sharpness The following shows a 100% crop area near the bottom right hand corner in each of the images. Note that the size of the objects in the Sammy images are smaller since they are identical scale crops from an image with a larger field of view (so things look smaller!) Sharpness Comparison: To remove the magnification effects, I downsized the Oly 9-18 shot so that it matched that of the Sammy. Here is the comparison: Scaled comparison of Oly and Defished Sammy at 9mm It can't be said that any of the corners are super sharp, but I think that the Rok defished images are actually pretty good - certainly no worse than the 9-18, even at a focal length approaching that of a 6mm equiv prime. Until my craving for a nice native 7 or 8mm prime is satisfied, I'm fairly happy that the defished Rok delivers, albeit with some extra time in PP.