So I own the Samyang 100mm 2.8 macro for Nikon, and I have used it on both Sony and Fuji and Nikon. However, it always seem to be sharper on the Nikon camera for some reason, not by much, but noticable. I have tried several copies of my friends lenses and came to the same results. However when I tried several copies of the lens made for Sony FE and Fuji X they were as sharp as the Nikon was on the Nikon body, no matter what the resolution of the sensor. I mean, the only difference what I know of is that the FE mount and X mount have built in adapters in the lens barrel. Can it be that the adapters are taking away some sharpness? But that would be weird since they don't contain any glass, and if they were faulty they would have messed with infinity focus or something like that. Anyone who can explain this?