haven't had a chance to do real tests yet, but I did take a few test shots in my garden to check for sharpness loss and color stem. I used a macro lens to check fine detail and a wide angle to see if it was consistent throughout the frame. I also compared it to my Lee Filters-sized stopper. I couldn't detect any significant loss of sharpness throughout the frame with either the macro or wide angle. There is a small color cast when looking at the exif data, but the in-camera shot has mostly adjusted it and can be edited manually if needed. Importantly, it seems to be consistent across the frame, even at 10mm on my apsc sensor. I've experienced the angling at wide angles (both 10mm and 22mm) but again it can be edited very quickly in Lightroom. It would have been nice if it came with a light gasket but for the massive difference in price compared to the bigger brands I can forgive them that. They can be purchased elsewhere online if needed, which I will do. Overall I'm pretty happy with it which is just as good as it made the slip through my Lee Filters binder when I wasn't paying attention and fell on the paving stones in my garden chipping the corners of the glass. That's my own fault though as it's a known issue I have with the holder, same issue with my Nisi filters in my holder so I think it's a bit worn out.