The E screen in this series was for the FE. The E2 screen was made for the FE2. The E3 screen was made for the FM3A. If you use a screen in a camera it was not originally made for you will have to provide some exposure compensation. The Nikon F2 went out of production in 1980 and did not have, as far as I know, an E type screen as bright as that of the FM3A (E3). A benefit of using the F2 is that it shows very little distortion in the finder. The actual distortion a lens has will show up looking the same on any body but an F2, for example, shows less finder distortion than a Nikkormat FT3.