Physically holding down the power button is often used with remote power supplies, to allow the camera to boot when power is applied.
I discovered that this prevents the normal Canon power saving feature (Display off after...) from working.
This can be avoided by using
post_levent_to_ui'UnpressPowerButton'
after startup. Verified on sx160 and a4000
IIRC there have been other side effects observed from the power button hack,so this might be helpful in other cases too.
The Canon screen off setting can be used to turn off the sensor (not just the display) between shots for long intervals, without switching to playback or retracting the lens.
To use this, go to "Power Saving" in the Canon settings menu, turn "Auto power off" off, and set "Display off" to the desired time.
If using a script, the "CHDK disable lcd off" should be set to never.
