UBasic/Scripts: G7 HDR Bracketing

G7 HDR Bracketing

Written for/on: G7

Also works on: none

Required CHDK build: I'm using Fingalo's Testbuild (ver 19), I'm sure most anything will work

Brackets through the exposure on the camera, fairly simple. The whole thing runs in about 30 seconds for 5 shots. I tried using the script HDR for G7 but it would not bracket properly (I think the half second exposures did that...), and I also wanted to be able to change the number of shots (maybe use 3 instead of 5), I wrote this at night so my testing happened in a dimly lit room so the shutter likely took too long for that script to work right.

Documentation/Help (save as a small "G7-hdr.txt" file to your /CHDK/SCRIPTS/ folder)

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Run this in "P Mode" on the camera and make sure the exposure bar IS NOT SHOWING, otherwise the script will close it...then try and adjust the exposure with it closed, which won't work.

Also disable any picture preview after the shot, it takes up time/fudges the script.

There are three settings:

1. "Exposure count" does what you think it does, if you want 3 bracketed pictures, put in 3, if you want 5, enter 5.

2. "sleep" is the delay (in milliseconds) between each "click" of the knob, putting it as 0 might work...I've not tried that.

3. "long_wait" is the delay in milliseconds/10, 50 means 1/2 a second, 100 means a full second. This delay is how long the camera waits after taking the picture to begin moving the exposure up. This is very important because the camera takes a little bit of time for the shutter to fire and the picture to be written to the card, any lower and the camera will start moving the knob and the script will not work right. If you use RAW mode you might want to make that 50 a 200 or something higher to account for the long write time of the RAW.

At 3am in a poorly lit room, 50 works good, at noon outdoors where there's lots of sunshine, something like 35 might work quicker.

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Script Code (save as "G7-hdr.bas" to your /CHDK/SCRIPTS/ folder)

rem Author - AdamSteele

rem Written for G7 ONLY

rem Set the camera in P mode

rem I'm using Fingalo's Testbuild (ver 19) (allbest versions)
rem See the wiki for some special info

@title G7 HDR
@param a Exposure Count
@default a 5
@param b sleep
@default b 50
@param c long_wait
@default c 50

c=c*10


print "Prep time"
click "expo_corr"
let i = 1


for x = 1 to 12
  wheel_left
  sleep b
next x

sleep c

for y = 1 to a
	print "Shot", i, "of", a
	i = i + 1
	shoot
	sleep c
	
	for x = 1 to (12/(a-1))
		wheel_right
		sleep b
	next x

	sleep c
next y


print "Resetting..."
for x = 1 to 6
  wheel_left
  sleep b
next x

click "expo_corr"

end

--Adamsteele

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Steps for dummies:

1) On a PC, put the file "G7-hdr.bas" (this is the file you created by copy and paste the lines above into Notepad and then save as G7-hdr.bas or whatever filename you like with the *.bas extension) to your /CHDK/SCRIPT folder and then

2) On your G7, change to ALT mode;

3) press FUNC/SET button to go into script mode;

4) choose the "Load script from file" menu and choose the G7-hdr.bas file;

5) change the settings if you want; (please refer to the lines above);

6) press Menu button to leave script mode;

7) while still in ALT mode, press the shutter button and G7 will start taking photos automatically and reset the aperture at the end;

8) make sure you go back to script mode and change the script back to 'Default.bas' (follow step 2 to 4 above) when you finished, otherwise the script will remain even you turn off and on your camera.

Happy photo shooting.

Sai Keung.