Ground glass performance

I have alot of enquires about the different grades of ground glass so I'm putting the description here...Here's the difference between the 3 different grinds. the 20 micron grind is the roughest. It works best with adapters without a PCX/Condenser lens as the better diffusion cuts down on vignetting/hotspotting, however it also produces a softer picture and some grain/noise. The 5 micron grind produces the sharpest picture. It is grain free but produces slight vignetting/hotspotting when used in an adapter with PCX/Condenser lens. This will not be ideal on adapters without the PCX/Condenser lens as it will produce severe vignetting. The 9 grind is the best performing focusing screen in my opinion. In adapters with a PCX/Condenser lens, it exhibits no vignetting and the picture quality in between the 5 and the 20 which makes it a touch softer than the 5 micron grind. This makes the image look more filmic. I wanted to add that with the GT35pro Adapter, the vignetting does not apply here as it has 2 different lenses installed inside. One is a magnifier and the other is a condenser lens. This is in addition to the achromat.