DXIDXO(OPCS)		Optical Printer Control System		DXIDXO(OPCS)

        dxi/dxo  - set up dissolve in/out

        dxi [-x] frames
        dxo [-x] frames

        dxi 12        # set up a 12 frame 'dissolve in'
        dxi -x 12     # 12x fade, regardless of current fader position

        -x  This allows dissolves to be setup even if the fader is not
            fully open or fully closed. (Errors are disabled)

        Sets up a dissolve in or out, so that any commands involving exposing
        camera film (cam, rep, etc), the fader will automatically move 
        to the proper positions for each frame.

        1) Setup and shoot a 12x "dissolve in" on a held projector image:

            dxi 12 cam 12
              |      |
              |      Shoot 12x dissolve in on frozen projector frame.
              Set up the 12x dissolve in

        2) Setup and shoot 12x "dissolve in" as a straight print:

            rat 1 1 dxi 12 rep 12
              |       |      |
              |       |      Shoot 12x dissolve in on moving projector image
              |       |
              |       Set up 12x dissolve in
              Set up a straight print for the 'rep' command

	3) Setup and shoot a 24x 'lap dissolve' between two moving projector
	   images. (Assumes 'rat 1 1' in effect for straight print):

            dxo 24 rep 24 seek >5500 -24 dxi 24 rep 24
              |      |          |          |      |
              |      |          |          |      Shoot 24x dissove in
              |      |          |          |      as straight print
              |      |          |          |
              |      |          |          Setup 24x dissolve in
              |      |          |
              |      |          Backwind camera -24x, projector seeks x5500
              |      |
              |      Shoot 24x dissolve out (straight print)
              Set up 24x dissolve out

           Commands can be 'all on one line' as shown above, or separate:

              dxo 24            # Setup 24x dx out
              rep 24            # Shoot 24x dx out as straight print
              seek >5500 -24    # Backwind cam -24x, pro goes to frame #5500
              dxi 24            # Setup 24x dx in
              rep 24            # Shoot 24x dx in as straight print

           Note: seek >5500 -24 is effectively the same as cam -24 pro >5500
           though the latter may be slower to execute.

        4) Set up and shoot (12) 4 frame lap dissolves between every 8th
           projector image:

            do 12 dxo 4 cam 4 seek -4 pro 8 dxi 4 cam 4
                  ^These commands repeat 12 times from left to right.

           ..having the effect of 'weaving' still frames from an otherwise
           slow-motion moving projector image.

        opn, cls, shu, dxi 0, dxo 0 will cancel any pending dissolves.

        A status message near the fader's counter shows how many frames are 
        left to go for the dissolve. 

        If the -x flag is NOT supplied, the fader:

            o Must be fully OPEN before executing DXO (dissolve-out).
            o Must be fully CLOSED before executing DXI (dissolve-in).

        ..otherwise an error will be printed. Below are common errors:

            dxi 12  cam 11 dxo 12  cam 12
                           ^bombs here: only 11x into a 12x DXI.

            opn  dxi 12  cam 12
                 ^bombs here: fader is already open

        It's hard to see such errors with the naked eye, especially in large
        '.run' scripts, so it's highly advised to test such scripts with 
        'motors off' in effect. This lets you run the script 
        to find such errors quickly, without wasting film.

        When setting up a new system, shoot extensive cross-dissolve tests
        to make sure the INTERP(OPCSDEFS) values for your fader are correct.

        If the interp values aren't accurate, or there is slop in the fader
        mechanics (See SLOP(OPCSDEFS)), you will find out quickly by shooting
        multiple lap-dissolves of grayscale charts using different dissolve
        lengths on sensitive stock, and then /projecting/ the result.

        Fine tuning SLOP and INTERP are essential for accurate dissolves.

	-- Operator Commands --
        CAM	  - shoot camera (fades/dissolves too)
        OPN	  - open the fader shutter to 170 degrees
	SHU 	  - send fader shutter to an absolute position
	CLS	  - close the fader shutter to 0 degrees
        DXI/DXO   - set up dissolve in/out
        FDI/FDO   - set up fade in/out

	-- Opcs Setup Commands --
	FLOG      - set Fader LOGarithmic curve for custom fades
	FRANGE    - set fade/dx's degrees range (for Hicon film stocks)
	INTERP    - set interpolation positions (fader, focus, etc)
	SLOP      - correct for slop in a motor (fader, focus, etc)

        Gregory Ercolano, Los Feliz California 11/29/89

© Copyright 1997 Greg Ercolano. All rights reserved.