Canon Camera Hackers Manual page 243

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C H A P T E R 8 Kites, Balloons, and Multikopters
When such missions last for a long time, it is necessary to evaluate the
power supply and provide the camera with external power, e.g., from a ve-
hicle's batteries. A voltage regulator is needed to match the supply voltage
with the voltage required by the camera. Also needed is a way to feed the
current into the camera. A simple solution is salvaging a cheap replace-
ment battery and connecting its contacts with the output of the voltage
regulator. Alternatively, a dummy battery pack can be made from card-
board using paperclips as contacts. In a similar way, it is possible to supply
the camera with current from the USB port of a notebook computer or
from a solar panel. Most stationary-mounted cameras, however, can be
supplied with current from an AC outlet by using the standard AC power
supply unit from the camera manufacturer.
If the camera is not accessible, it is worthwhile to install a backup bat-
tery, too. If the power shuts down due to a supply current dropout, there is
no way to turn the camera back on again—except, perhaps, via a robotic
arm that presses the power button. Also, before a mission, make absolutely
sure the Auto Power Down function of your camera is switched off.
If the camera is running on its own battery, power saving is essential. In
most cases, the camera display is not used during the mission, so the dis-
play backlight can be switched off. If the script operating the camera does
not switch the backlight off, you can insert a spare AV plug into the cam-
era's AV OUT terminal, which will switch off the display backlight.
Another problem is that after a shorter or longer period of time, the
memory card will be full. Exchanging the memory card can sometimes be
cumbersome. Basically, there are two options to solve the problem. If the
camera can be connected to the USB port of a nearby PC, the images can be
downloaded to the hard disk of the PC by using the SDM in connection with
the WIA loader (section 7.6). The other option requires a suitable Wi-Fi
hotspot, a Wi-Fi router, or a Wi-Fi enabled computer nearby. If this is avail-
able, the camera's memory card can be exchanged against an Eye-fi card.
The Pro version of this card can hook into different wireless networks and
upload images to a photo-sharing site on the Web or to a computer.