The idea that a particular lens can’t be focused on an SLR is illogical. The basic idea of an SLR is—what you see on the focusing screen is what you get on film.

While the focusing screens of the F4 automatic focus camera is intended for the use of AF lenses, manual focusing is still possible.

You can install the K screen for the same type of screen as used on the F3. This gives you both a central split-image with microprism ring as focusing aids. This makes focusing manual focus lenses on the F4 easier.