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Not capturing enough photos - Weather Balloon Project

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Offline dw1

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Not capturing enough photos - Weather Balloon Project
« on: 01 / May / 2010, 10:35:55 »
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Hi

Have been using a PowerShot SD 750.
Have a script to capture photos every 20 seconds.
I have a new battery.

Problem: I am only getting 360 or so shots on every test.
Battery will run out of power.

Have adjusted settings: No flash, no auto focus. Using "yass - sunset script".
Have tried other scripts and same thing.

Thoughts? Thanks in advance.
-Dave
« Last Edit: 01 / May / 2010, 10:48:14 by dw1 »
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Offline fe50

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Re: Not capturing enough photos - Weather Balloon Project
« Reply #1 on: 01 / May / 2010, 12:21:55 »
Hello & welcome, Dave !

Quote from: dw1 on 01 / May / 2010, 10:35:55
Have been using a PowerShot SD 750.
Have a script to capture photos every 20 seconds.
I have a new battery.
Problem: I am only getting 360 or so shots on every test.
That's a typical value for this camera; the official Canon value for the SD750 with the NB-4L battery is ~210 shots (CIPA; "The above figures comply with CIPA testing standards and apply when a fully-charged battery is used") --> http://www.canon.com/camera-museum/camera/dcc/data/2007-/2007_ixyd_90.html?lang=us&categ=crn&page=2007-&p=2

You can enhance the battery lifetime by disabling the LCD backlight or the display (including the sensor; max. power saving, but not possible with motion detection); with an optimized script you should get 2-4 times more shots.
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Offline dw1

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Re: Not capturing enough photos - Weather Balloon Project
« Reply #2 on: 01 / May / 2010, 12:45:01 »
I have read about using AV OUT input and placing a connecter into jack to turn the LCD off.
As far as the script goes, I am approaching the 2x factor of the standard ~210 shots for this battery.

Will try to tweak for maximum number of shots.

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My stats so far:
1. 336 shots at 20 second intervals = 112 minutes before battery runs out.
2. Projected flight time = 2hrs 32mins = 152 minutes
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Balloon Trajectory Forecasts:
Have been using a great resource for flight path projections at:
http://weather.uwyo.edu/polar/balloon_traj.html

Gives you a better understanding of flight times and with google earth you can plot your balloon path.

Appreciate the ability to use CHDK & the forum to fine tune for our Weather Balloon Project.
We will post our information once we launch.

Great resource! Thanks.
-Dave
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Offline fe50

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Re: Not capturing enough photos - Weather Balloon Project
« Reply #3 on: 01 / May / 2010, 14:17:10 »
The AV trick could help, just plug in something, e.g. a small piece of wood or the end of a shoe lace; this disables the LCD backlight.
See also the set_backlight scripting command to do the same with a script command:  http://chdk.wikia.com/wiki/CHDK_firmware_usage/MoreBest#set_backlight.28.29

The LCD backlight don't consume much power, i guess this could give you ~ 20-30% more battery lifetime;
turning off the display would give much more battery lifetime since with this method the sensor (which consumes most power) is also off while the camera "sleeps".

Unfortunately the SD750 is one of the Powershots where you can't turn off the display directly with the DISP button - but the following workaround does the trick:

1) register the PRINT/Shortcut button with the "Sleep ZZzz" function in the Canon menu
2) simulate a keypress to the PRINT key in your script after an image is stored, e.g. with a code sequence like this:

 press "print"
 sleep 200
 release "print"

You'll find more background information in this old thread: http://chdk.setepontos.com/index.php/topic,1768.0.html

Another option is to switch to playback mode while you want the camera to sleep, e.g. with the set_record scripting command: http://chdk.wikia.com/wiki/CHDK/MoreBest#set_record.28state.29 (but with only 20s between the shots this may be not very efficient)
« Last Edit: 01 / May / 2010, 14:18:53 by fe50 »
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Offline dw1

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Re: Not capturing enough photos - Weather Balloon Project
« Reply #4 on: 01 / May / 2010, 15:01:14 »
I have an av connector in the camera now while it's running the script. LCD is off.
If I can squeeze another 20-30% out of the camera battery that would do it.

We lift off tomorrow so I will limit the options since we are running out of time.

We've been testing scripts for a week or two and thought by purchasing a new battery that would potentially double the shots since the older batteries didn't hold a full charge. Have just scratched the surface of many of the CHDK scripts and settings. Am very impressed at the practical applications for running scripts and will be jumping in deeper to learn more after our balloon launch.

Had a time lapse of the moon rise at sunset. You can see the house lights come on one by one in the neighborhood below the moon. Very cool.

Thanks.
- Dave
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Offline reyalp

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Re: Not capturing enough photos - Weather Balloon Project
« Reply #5 on: 01 / May / 2010, 18:10:46 »
Quote from: fe50 on 01 / May / 2010, 14:17:10
Unfortunately the SD750 is one of the Powershots where you can't turn off the display directly with the DISP button - but the following workaround does the trick:
I wonder if if the "PressDispButton" levent still works on these cameras ? Would be worth a try. In lua
post_levent_to_ui("PressDispButton")
post_levent_to_ui("UnpressDispButton")

This should be the best way to save power for a relatively long interval like 20 sec, since it turns of the sensor, display hardware and probably puts the CPU in a low power mode.

Keep in mind that if the camera gets cold on the balloon flight, usable battery capacity will be severely affected.
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Offline dw1

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Re: Not capturing enough photos - Weather Balloon Project
« Reply #6 on: 02 / May / 2010, 00:46:49 »
Quote
Keep in mind that if the camera gets cold on the balloon flight, usable battery capacity will be severely affected.
Excellent point. Have hand warmers around camera and our cell phone used for tracking the payload.

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Stats with AV Connector plugged in. Test #1-AV:
1. 675 photos at 20 second intervals = 3hrs 45mins = 225 minutes / Battery on 0%
2. Projected flight time = 2hrs 32mins = 152 minutes
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That will do the trick.
Thanks.
-Dave
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