PROPHASE(OPCSDEFS)      Optical Printer Control System    PROPHASE(OPCSDEFS)

    NAME
	prophase - configure projector's phase adjustment for 1:1 shooting

    USAGE
        prophase [chan] [pulses]   # sets number of pulses channel 
                                   # will move before shooting 1:1

    EXAMPLES
        prophase a 200             # half-stepper systems (400 ppr)
        prophase b 200             # 

        prophase a 1000            # Centent microsteppers (2000 ppr)
        prophase b 1000            #

        prophase a 1600            # Lynx microsteppers (3200 ppr)
        prophase b 1600            #

    DESCRIPTION
        Sets the projector phase adjustment (in motor pulses). Phase adjustment
	occurs just before and just after 1:1 ratio shooting. This phase 
	adjustment is necessary so the projector(s) and camera can run 
	together, only exposing film when the projector images are seated.

	Almost without exception, the prophase command:

		1) Is always set to be 1/2 the number of pulses for  one
		   motor revolution. This includes  Vistavision movements.
		   On a system where one switches back and forth  between
		   Vista / 35mm / 16mm, the prophase value does NOT  change,
		   even though the PPR(OPCSDEFS) value may  change.

		2) Is set ONLY for the projectors. A value of '0' should  be
		   set for all the other  channels.
		   
		   The prophase value is actually ignored by the other
		   channels, so it doesn't really matter what the values 
		   are for non-projector channels. But specifying '0'
		   makes it clear the value is ignored.

    BUGS
        None reported.

    SEE ALSO
        RAT(OPCS)           - set the shooting ratio for the REP command
        REP(OPCS)           - shoot current projector/camera shooting ratio
        PROPHASE(OPCSDEFS)  - sets projector phase adjustment for 1:1 shooting
        MATH(DOCS)          - math expressions (for use in frame specifications)
        SYNTAX(OPCS)        - Online calculator and OPCS math expression syntax

    ORIGIN
	Gregory Ercolano, Los Feliz California 12/15/89