[Brightcolours]

I guess the answer to my questions is no, you are not clear on the fundamentals.

 

I give up, you are only interested to flame my knowledge and pretend you have knowledge which you do not.

You thinking that front or back focus of a lens has any connection to the focus screen, and that the focus screen should be adjusted to different lenses, it tell tale enough.

That is fine. Have a nice new year!