Olympus OM-1 Repair Manual page 31

B-10
(4) Shutter Timing:
of Operation
(ms)
Shutter
Release
Mirror
elected.
First
Curtain
starts.
First
Curtain
finishes
its run.
Second
C urta in
Starts.
Second Overall
Curtain operation
finishes completed,
its run.
Mirror
lowered.
The above timing is based on the curtain movement from one edge to
another edge of the mask. Therefore, it does not include the
movement of the first and the second curtains before they appear
one end of the mask and after they will have reached the other end
of the mask.
http://olvmpus.demcnti