Old m42 lens and SFD
I tested the resolution of one of my old M42 mount lenses using the SFD mode of my Quattro.
This was shot at f8.
The lens is the tiny Industar 50mm F3.5
I used Raw Therapee to process the auto exported Tiff image. It required a large amount of contrast boost. I used the contrast by detail function instead of normal sharpening.