FDIFDO(OPCS)		Optical Printer Control System		FDIFDO(OPCS)

    NAME
        fdi/fdo  - set up an automatic fade in/out

    USAGE
        fdi [-x] frames
	fdo [-x] frames

	The -x option overrides the error message that warns you about doing a
	fade when the shutter isn't fully open/closed. This allows you to
	do fades from any fader position.

    EXAMPLES
        fdi 24           # Set up a 24 frame fade in
        fdi -x 24        # 24x fade, regardless of current fader position

    DESCRIPTION
        Set up a fade. Whenever the camera is told to expose a frame (with 
	CAM(OPCS), REP(OPCS), etc), the fader will automatically move to
	the proper positions before exposing each frame.

	Fades are based on a logarithmic curve that can be customized 
	with FLOG(OPCSDEFS).

	Fades can occur on either still or moving images, depending on the
	command used for exposing film;

	    1) fdi 12 cam 12          # fade in
	    2) rat 1 2 fdo 12 rep 6   # fade out with step print

	#1 sets up and shoots a 12 frame fade-in on a still projector image.

	#2 sets up and shoots a 12 frame fade-out on a moving projector image 
	on twos.

	Fades will remain in effect until all frames of the fade have
	been shot. The following are equivalent, and all shoot fades 
	similarly:

	    > fdi 12 cam 12
	    > fdi 12 cam 6 cam 6
	    > fdi 12 cam 6 pro 1 pro -1 cam 6

     NOTES
	> fdi 0, fdo 0 or a SHU(OPCS) command with any value
	  will cancel any pending fade or dissolve.

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

	> Normally, the fader must be:

	    o OPEN before executing FDO
	    o CLOSED before executing FDI

          If not, an error message will be generated warning you of the
	  situation.

	  The only exception is if -x is supplied, preventing
	  error messages, shooting the fade based on the fader's *current*
	  position.

	  Below are some common errors:

	      fdi 12  cam 11 fdo 12  cam 12
	                     ^bombs here: only 11x into a 12x FDI.

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

	  To spot this kind of error, especially in large RUN scripts, it is 
	  highly advised you make a test run with motors off in effect.
	  This allows you to run the script to check for such errors 
	  without exposing film or waiting for motors to spin.

    SEE ALSO
	-- 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)

    ORIGIN
	Gregory Ercolano, Los Feliz California 11/29/89

© Copyright 1997 Greg Ercolano. All rights reserved.