FUJICA AX-3 Owner's Manual page 20

Shooting with a Praktica thread mount Fujinon Lens (Mounted with the Mount
Adapter X-S)
1. Set the Shutter Speed Selector to AE or AE L.
2. Set the Aperture Ring to the desired value.
3. Press in the Preview Button and, while holding it there, look through
the Viewfinder and press the Shutter Release halfway down to make sure
that neither the overexposure nor the underexposure warning signal is
blinking.
4. Take your picture by pressing the Shutter Release gently down.