Name:    Flash Bounce
Models:  fx-4000P and above
Size:    48 bytes
Version: 1.0
Author:  Lupus Yonderboy
E-mail:  lupusy@Tesla.rcub.bg.ac.yu
URL:     http://www.rcub.bg.ac.yu/~lupusy/

Description:

   I  am hoping this will help you to use bounce flash if you have manual
   flash or no TTL flash cameras.

   This  program will calculate angle of the flash head and lenght of the
   light  path  using  the  flash to ceiling distance and flash to object
   distance.  See examples for more informations.


Usage:

   Input:
   
   c - distance from the flash to the ceiling
   d - distance from the flash to the subject

   Output:

   Ang - angle of the flash (relative to the horizontal)
   LPD - light path distance

Examples:

c?
1.5
d?
3
Ang=
              45
LPD=
            4.24

   OK,  what  is  all  this?   You have this situation:  you are ready to
   shoot,  ceiling  is  1.5m above the flash, and your subject is 3m from
   you.   Program  suggests  that  you tilt flash head 45 degrees and use
   aperture you would use if your object was 4.24m away.

c?
1.5
d?
6
Ang=
           26.57
LPD=
            6.71

   This  one?   Ceiling  is  1.5m  away  (again),  and object is now at 6
   meters.   You  should  tild  flash  head  for 26 to 27 degrees and use
   aperture as if object was 6.7m away.


   Now,  these  calculation  do not take into account light losses due to
   dispersion  or darker ceiling, it just act sa if 100% of the light was
   relfected.   And  that  is  simply  not true.  So, add 25 - 50% to the
   calculations.   That  means,  add  one  half-stop  to  one  full stop.
   Experience  will  do  it's  job,  this  porgram is just a quick way to
   precisely calculate flash angle and to inaccurate calculate aperure.