Seems like I am always trying to improve my focusing options, not just on my Rolleiflex, but also on all my older cameras and particularly on my LF cameras. There are a lot of factors to consider from the type of glass to the grit and process used, acid treatment, optical coatings, and then of course fresnels are almost their own subject.  Lens fit to the camera can also affect the type of screen and fresnel you might want. IRead more