FUJICA AX-3 Owner's Manual page 32

1. Clip the strobe foot into the camera's accessory shoe.
2. Use any shutter speed except B.
3. If you are using an X-Fujinon DM lens, set the Strobe's F-number dial
to F1.4 (marked in red). If you are using an X-Fujinon lens, set it to the
maximum aperture of the lens.
4. You can use any aperture you wish but the shooting distance will differ
depending on the aperture and the speed of the film you are using. (Use
the accompanying chart as your guide for selecting the aperture).