Canon Camera, Hackers Manual

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4.9 Remote control
69
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Enable Remote Zoom . Allows controlling the zoom of multiple synchro-
nized cameras through the remote control on cameras with a single
zoom switch or rocker. To do so, the camera must first be brought into
remote zoom mode. This is done by manually clicking the zoom switch
quickly. The blue
<Alt> button should light up, and the zoom can now be
operated using the button on the remote. When it reaches the longest
or shortest focal length, the zoom direction will reverse. You can exit the
zoom mode by half-pressing the shutter button, by half-pressing the
Ricoh switch, or by simply waiting for time-out (see below). Afterwards,
the remote control can be used to fire the shutter.
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Zoom Time-out 0.1s . Specifies a zoom time-out value in seconds. (The
label specifies an incorrect time unit of 0.1 sec. The actual time unit is
1 sec.) After this time, the camera leaves the zoom mode and returns to
normal shooting mode. Time-out values between 2 and 10 seconds are
possible.
4.9.4 Extra hardware
It isn’t really necessary to learn soldering to get your own remote control
device. Some vendors are offering devices that can hook up to the camera’s
USB port and that are supported by the CHDK.
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The Ricoh CA1 USB remote control works with the CHDK functions
listed under “synchable remote”. The release button has a half-pressed
and a pressed position. A double click is therefore not necessary to
shoot a picture. A single 1.5V AAA cell powers the device. A built-in
DC-DC converter pushes the 1.5V up to the required signal voltage.
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The GentLED devices from Gentles Limited ( www.gentles.ltd.uk/
gentled/ ) allow remote control of cameras by wire, infrared, or RC con-
trol systems. These products support both the Ricoh CA1 and the native
CHDK protocol. Using the native protocol, these devices can encode
different functions using different pulse lengths that can be evaluated
by a script. For example, the different joysticks of an RC remote control
can be assigned to different functions, such as shooting, zooming, or
focusing.
4.9.5 Tethered shooting?
Tethered shooting is the ability to transfer images immediately to a con-
nected PC without saving them on a memory card. In a studio situation or
for time-lapse work, this makes a lot of sense because you aren’t limited by
the capacity of the card. You also save the extra step of transferring images.