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Exposure bracketing on SD870

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Exposure bracketing on SD870
« on: 21 / May / 2008, 16:18:15 »
Is anyone successfully using exposure bracketing on the SD870/Ixus 860?
Since the camera uses a neutral density to set either f/2.8 or f/8, and doesn't have an iris, I am hoping to find a script that brackets using shutter speed settings only (no aperture settings).

If anybody can point me to such a script, I'd greatly appreciate it.


Offline fudgey

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Re: Exposure bracketing on SD870
« Reply #1 on: 21 / May / 2008, 17:23:48 »
Why don't you just use the CHDK built-in continuous mode (Tv) bracketing?

Re: Exposure bracketing on SD870
« Reply #2 on: 24 / May / 2008, 14:17:29 »
As far as I know, I can't use the Tv bracketing in continuous mode because the camera is up in the air on a kite line taking aerial photos, and it's being triggered using a USB remote script.  It would be ideal if the camera would take 3 photos automatically in 1/3 or 2/3 EV increments each time it receives the USB triggering pulse.

Example of kite aerial photography:  http://www.flickr.com/photos/ml_kap/2127796341/


Offline vine

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Re: Exposure bracketing on SD870
« Reply #3 on: 24 / May / 2008, 14:42:07 »
can be easily done with a script
something like:
Code: [Select]
wait_click 1
is_key k "remote"
if k=1 then goto "shots"
goto "loop"

get_jpg_count x
press "shoot_half"
sleep 1000
press "shoot_full"
  get_jpg_count z
until z=y
release "shoot_full"
release "shoot_half"
print "Take",i,"done"
goto "loop"

where a is the number of shots
« Last Edit: 24 / May / 2008, 14:49:05 by vine »
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Offline fe50

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Re: Exposure bracketing on SD870
« Reply #4 on: 24 / May / 2008, 14:46:32 »
So if you trigger with USB you have to work with a script...

In the german forum there's a script "Belichtungsreihe Fix-Focus", in german language but it can be translated easily...it's not with USB  control yet.
(for DigicII, get_prop 205 have to be changed to 206 for DigicIII)

The Script does focusing only one time, then the focus is fixed.

It's an extension of a script originally written by CHDKLover and msl, maybe they can help you ...

Re: Exposure bracketing on SD870
« Reply #5 on: 24 / May / 2008, 17:06:13 »
Thanks very much for your suggestions, Vine and fe50.  I'll play around and if I have questions I will post them here.


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