Does anyone know if focusing screens made for the Mamiya C330 S are interchangeable with screens made for the C 330 F (i.e. can I use screens/frames made for an S camera in an F camera or vice versa)? And, also, what the specific differences are between them? I ask because of a notation I read in the Mamiya TLR System Summary that noted; "The C330s uses different screens and a different mounting method from the C330 and C330f". I originally assumed I could use newer screens made for a 330 S in my f camera. Now, I assume, I was wrong in that assumption. Thanks for any clarity on this.