FUJICA AX-3 Owner's Manual page 30

3. Set the Strobe's Distance Selector to either the yellow, green, or red
mark. Them marks represent the following shooting distances:
Yellow .......1 - 2.7 m {3.3 - 8.9 ft.)
Green .......1 - 5.3 m (3.3 - 17.5 ft.)
Red ......... 1.5 - 10.7 m (5 - 35.3 ft.)
4. Set the ISO/ASA speed selector on the strobe back to the number
corresponding to the speed of the film you are using.
5. Read off the aperture you need for the color of the mark you selected
and set the camera's aperture ring accordingly.
Example: If you are using an
ISO/ASA 100 film (Fuji color
HR100) and have set the
Strobe's Distance Selector to
the green mark, the aperture is
F5.6 so you'll have to set the
camera's aperture to F5.6.
6. Turn on the Strobe Switch.