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Squeezing more battery life out of an A470 for long timelapses

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Hi Everyone,

Thanks to the awesome people here who have devoted their time to developing CHDK and preparing the excellent online documentation on the camera, I've been able to capture some great timelapses using an A470 hidden in trees around town.  I'm now starting to reach the limits of the camera, and am wondering if there's anything you can suggest to get more photos out of the camera during long timelapses.

I've already got the LCD timer set to 10 seconds (that's as low as it will go) and I've experimented with sticking a chopped off 3.5mm headphone jack into the AV plug, but that doesn't seem to save much battery life.  I'm also using the best 2500mah rechargeable NiMH batteries I can get, and I'd rather not increase the bulk/decrease the stealth of the camera with an external battery pack.

Is there anything else that I could be writing into the intervalometer script or otherwise changing to squeeze a couple more photos out of the camera on each timelapse?  It's frustrating that I can't turn off the LCD entirely; since there's no optical viewfinder on the camera there's no DISP button to push and this no way to kill the LCD completely... or is there?

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Offline reyalp

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Re: Squeezing more battery life out of an A470 for long timelapses
« Reply #1 on: 25 / June / 2010, 19:27:55 »
If you tell us approximately how many exposures you are getting, others might be able to tell you if they've been able to exceed that.

To turn off the display, you can try (lua only)
Code: [Select]
post_levent_to_ui("PressDispButton")
sleep(100) -- may not be needed
post_levent_to_ui("UnpressDispButton")
This may or may not work on cameras without a disp button. ISTR someone also told me that holding the print button turns off the display on this camera.
Don't forget what the H stands for.

Re: Squeezing more battery life out of an A470 for long timelapses
« Reply #2 on: 25 / June / 2010, 23:28:07 »
Using the print button: that's a neat tip.  It does have a similar effect to pressing the DISP button on another A-series camera because it turns off the on-screen shooting info.  But pressing and holding again just turns it back on, it doesn't turn the LCD off.

I'm currently getting 439 exposures, that's in good light with the AF-assist turned off, one exposure every 20 seconds with a 4 hour delay before the first shot.  That's with nothing stuck in the AV port, and the LCD-timeout set to 10 seconds. In total, I get about 3 hours and 8 minutes of shooting time before the batteries give out.  I seem to be able to increase the delay at the beginning anywhere from nothing to 6 hours without seeing any consistent, noticeable drop in the number of frames, which is really great.

I'm not quite sure how to use the code in your post, it appears not to be uBasic; can I escape into another lower-level language somehow?

ETA: Just reading up on http://chdk.wikia.com/wiki/LUA right now.  Another language to learn, oh boy.

Is there any way to reduce the number of seconds before the LCD times out to something lower than 10 seconds?  The options in the Canon firmware menu seem pretty arbitrary; 10, so or 30 seconds, a miute, 2 or 3 minutes, and that's it.  if I could change it to 1 or 2, I'll bet that would help.

Also, it would be great to write my code in such a way that it DOES meter the exposure every time but does NOT check focus, is that possible?  
« Last Edit: 25 / June / 2010, 23:50:53 by EricFerguson »

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Offline fe50

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Re: Squeezing more battery life out of an A470 for long timelapses
« Reply #3 on: 26 / June / 2010, 06:44:48 »
EricFerguson:

On cameras without an optical viewfinder (DISP wont disable the display on these cameras) register the sleep function to the PRINT button in the Canon menu; then you can disable the display by holding PRINT (for ~0.75s) or with a emulated keypress to the PRINT button from a script.

This method disables the LCD, the LCD backlight and also most of the electronics, also the sensor - this gives most power savings.

See also here: http://chdk.setepontos.com/index.php/topic,5306.msg51443.html#msg51443


 

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