Pentax P3 - Film Handling and Selection

DX FILM
This camera automatically sets the ISO film speed
of DX-coded film when it is loaded into the film
chamber. Therefore, you are recommended to use
only DX-coded film in this camera. (If non-DX film
is loaded the camera will automatically set the film
speed to 100, whatever film speed it may have; in
other words, the only non-DX film usable for this
camera is one with ISO 100 .)
The film speeds which can be automatically set by
this camera range from ISO 25 to 1600 , so be sure
to use the DX-coded film having a film speed within
this range.