Got a Chinese diagonal split focus screen and the Pentax viewfinder magnifier. Gave it a fair go for a week with all my manual lenses but wasn"t happy (even after taking the plastic off
I don"t wear specs, and the diopter was set perfectly. Anyway, put the original OEM screen back and tried again just with the magnifier. Still not happy.
I then remembered the old Nikon Em body I hadn"t seen for yonks. It had died years ago. Looked thro" the VF and WOW. clear,clean and a bright split screen!!
Took out the Nikons focus screen after demolishing the camera and as I approached the end noted that I could have just removed two screws ...that would have done the same job !!!
Spent a very nervous day (not really) cutting and sanding the Nikon screen to fit the K200d....got to use my electronic digital calipers(Ebay special).
Well I'm thrilled..it's so bright I have to wear my sunnies and the focus was spot on (sheer luck).Brighter than the OEM and the Chinese screen.
I reckon if you can be bothered, just about any focus screen could be used..just a matter of cutting,sanding and patience. Oh Yeah..and an old unloved SLR....