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Turn Your Compact Canon Camera Into a Super-Camera With CHDK
Movie Zoom, RAW Mode
July 8, 2010
In CHDK part 1, you downloaded the Canon Hack Development Toolkit and got it running on your camera. By design it is safe to install and won't brick your camera. Now let's look at some of what CHDK offers.
Basic CHDK Features
CHDK gives you a whole new set of menus, accessed with the "Shortcut" key. So your first task is to identify that key. If your camera has a "Print" key, use that; if you have a key labeled "Shortcut", that's the one. If all else fails, check your camera's page on the CHDK wiki. When you find and press the Shortcut key, you'll see the word Alt in blue at the bottom of the screen (Figure 1).
Warning: when you're in ALT mode, you can't take photos normally, so press the Shortcut key again to leave ALT mode when you're ready to take pictures. Part 3 will discuss how to use the shutter button in ALT mode to run scripts.
Now you're ready to explore CHDK's extensive menu system. Press Shortcut, then Menu (Figure 2).
Extra Photo Operations gives you a whole slew of handy features, like using faster or slower shutter speeds or different apertures, as well as RAW mode settings (see below).
Ever been annoyed that your camera won't zoom in the middle of shooting a movie? The Video Parameters menu will let you fix that. Canon disables zooming because it introduces noise into the video -- but you may decide a few seconds of noise is worth being able to zoom. You also get much finer control over video bitrate and quality settings.
For many people, RAW mode is the best reason to use CHDK. A raw file contains a lot more information than a JPG -- it's basically a dump of everything the camera's sensor captured. It's especially helpful for complex images with a lot of bright and dark areas: the camera's sensor can record more brightness levels than it can encode into JPG, so if you have the RAW file you can choose whether to emphasize the light areas, the dark areas, or combine them.
CHDK also offers a key shortcut to toggle RAW mode on and off, but it isn't the same on all cameras. Go into Alt mode, then try +/- (which you may also think of as the Delete button), Func, Erase or Disp. Look for a tiny "RAW" notation on the lower right of the screen, as in Figure 1.
When you upload the raw files to your computer, use ufraw
to adjust colors and brightness levels and save them as other
formats. You can also install ufraw as a GIMP plug-in, so GIMP will
call it automatically when you open a raw file.