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sunset auto Tv exposure offset addition

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sunset auto Tv exposure offset addition
« on: 30 / October / 2009, 15:24:54 »
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First of all I want to thank Fbonomi who made the "Time lapse script variable shutter speed" Sunset4 script.
I have been using it with good success.

I have added one feature which is an offset to Shutter Tv.
So now I can over or under expose the shot in 1/3 stop increments. This is useful when shooting a sunny day to cut down on the glare burn out.

Since I did not come up with the script I did not want to post it under user written scripts. Unless that is ok???

Enjoy,
-Drew

Here is the addition.

  @param g 1/3 stop offset
  @default g 0

  rem Set Tv stop offset to 1/3 resolution
  g=g*32

  rem resulting Tv would be:
  T=B-A
  T=T+c-g

Here is the entire script if anyone wants to play with it. If you remove the math g=g*32 the resolution will be set to the standard 96.

  @title Auto TV
  rem Script to shoot time-lapse videos of sunsets
  rem v. 4, Fbonomi apr 30th 2008
  rem Released under GPL
  @param a Delay (sec)
  @default a 10
  @param g 1/3 stop offset
  @default g 0
  @param b Limit Tv
  @default b -414
  rem (-414=20 sec; -384=15 sec; -320=10 sec; -224=5 sec.)
  @param c Default Sv
  @default c 419
  rem (480=160)
  @param d Limit Sv
  @default d 419
  rem (419=100,776=1250 ISO; 960=5000)
  @param e Guess mode Threashold
  @default e -200
  @param f Increments in guess mode
  @default f 5
  print_screen 1
  rem Set Tv stop offset to 1/3 resolution
  g=g*32
  print "Auto Time Lapse"
  rem initialize guess mode value
  x=e
  rem get start Tv
  get_tv96 T
  rem picture counter
  p=1
  :loop
  rem measure luminance and aperture
  press "shoot_half"
  sleep 500
  release "shoot_half"
  get_bv96 B
  get_av96 A
  rem release "shoot_half"
  print "Measured: ",B ,A
  rem resulting Tv would be:
  T=B-A
  T=T+c-g
  print "Calculated T: ", T
  rem check Tv Values
  if T>e then
   rem normal mode, shoot with calculated Tv and default Sc
   X=T
   Y=c
   print "Mode: Standard"
  else
   rem Guess mode, every shot will be 5/96th steps longer
   x=x-f
   if  x>b then
    rem we are in dark, but exposure is not too long
    rem normal mode, shoot with guessed Tv and default Sc
    X=x
    Y=c
    print "Mode: Guess"
   else
    rem we are in very dark area, we want to avoid too long exposures
    rem shoot with maximum allowed time (b) and
    rem adjust Sv accordingly
    X=b
    Y=c+b-x 
    rem BUT check we don't go in too high ISO!
    if Y>d then
     Y=d
    endif 
    print "Mode: Guess with High ISO"
   endif
  endif
  rem we can now shoot
  sleep 100
  set_sv96 Y
  set_tv96_direct X
  sleep 100
  shoot
  sleep 100
  print "SHOOT ",p,X,Y
  p=p+1
  sleep a*1000
  goto "loop"

 

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