Canon Camera Hackers Manual page 17

8
C H A P T E R 2 Cameras and Operating Systems
Recent versions of the CHDK are able to deliver RAW data in the popular
DNG format, created by Adobe as a camera-manufacturer-independent
RAW format. It's a sensible choice; manufacturers of premium cameras
such as Hasselblad, Leica, and Pentax have chosen it as their native RAW
output format.
Scripting and motion detection
An outstanding feature of the CHDK is its ability to automate tasks by writ-
ing a script. While older versions of the CHDK support only the easy but
rather simplistic scripting language uBasic, newer versions come with
built-in support for the more advanced Lua language, which is also used by
Adobe Lightroom for automation purposes. With scripting, it becomes pos-
sible to shoot long time series or to let the camera operate autonomously,
as in unmanned aerial missions.
A rather surprising feature of both uBasic and Lua is the possibility of
motion detection. Under the control of a script, the camera shoots when
motion occurs within the image field, or if a detected motion stops. The
CHDK uses the camera sensor for this purpose, allowing highly configu-
rable motion detection without the need for extra hardware.
More control
Most Canon compact cameras operate automatically. If they offer a manual
mode, it enables you to dial in correction values for exposure but does not
allow you to set explicit values for shutter speed, aperture, or ISO speed, or
to focus manually. The CHDK, in contrast, enables you to do exactly that. Not
only is it possible to dial in precise values for shutter speed, aperture, ISO
speed, or focus distance, but the range of available shutter speeds is signifi-
cantly expanded. Extremely short shutter speeds, such as 1/60,000 sec., and
extremely long exposure times are possible under the control of the CHDK,
depending on the physical limits of the camera. For video clips, it becomes
possible to influence the video quality, and on some cameras, to enable the
optical zoom while shooting video.
Better information
While these possibilities extend the application range of the camera, the
additional OSD (On Screen Display) provides greater control over the gen-
eral image-making process. This starts with a battery meter that gives you
a precise readout (in percent) of the remaining battery power. This feature
alone makes it worth installing the CHDK, because shooting sessions and
battery usage can be planned in a much better way. Precise exposure con-
trol is achieved through a highly configurable live histogram and the