PDual will choose from the other two according to the focal length of thelens providing it is compatible with the 801 electronics. I have bought a second hand Nikon F-801S from a friend. It is great camera, unfortunately I don't have the operating manual for it. I have three choices, one is P, and Ph and Pd. Anyone can tell me the functions of these modes.
P stands for normal program.
Lenses with focal length shorter than 135mm. Phi is for lenses from 135 up,and selects higher speeds to reduce camera shake. PDual will choose from the other two according to the focal length of thelens providing it is compatible with the 801 electronics. Sorry for the banner but this page is not located on the original PhotoZone webserver.