What is CHDK? It’s a firmware enhancement (I like that word because it’s not a replacment) that work on many of Canons Cameras. 
CHDK gets loaded into your camera’s memory upon bootup (either manually or automatically). It provides additional functionality beyond that currently provided by the native camera firmware. The CHDK project allows users to non-destructively modify the firmware and write custom programs with new features.
CHDK is not a permanent firmware upgrade: you decide how it is loaded (manually or automatically) and you can always easily remove it.
Quick answers to 7 key questions about CHDK:
1. What is CHDK?
- CHDK is not just one thing! The term CHDK refers to free software – currently available for many (but not all) Canon PowerShot compact digital cameras – that you can load onto your camera’s memory card to give your camera greatly enhanced capabilities.
2. Am I likely to be interested in CHDK?
- The enhanced capabilities that CHDK provides are most likely to be of interest to experienced photographers – if you believe that your Canon PowerShot camera already has more features than you will ever need, you probably won’t be interested in CHDK.
3. Is CHDK safe to use?
- Probably. See this page for more information
4. How does CHDK work?
- CHDK makes use of the microprocessor that controls the camera (every digital camera contains a microprocessor) to act as a programmable computer that provides the extra capabilities.
5. What extra capabilities does CHDK provide?
- The current set of extra capabilities fall into six categories:
- a. Enhanced ways of recording images – you can capture still pictures in RAW format (as well as JPEG), and for video images you can have increased recording time and length (1 hour or 2 GB), and a greatly increased range of compression options.
- b. Additional data displays on the LCD screen – histogram, battery life indicator, depth of field, and many more.
- c. Additional photographic settings that are not available on the camera by itself – longer exposure times (up to 65 seconds), faster shutter speeds (1/25,000 sec, and faster in some cases), automatic bracketing of exposure, etc.
- d. The ability for the camera to run programs (‘scripts’, written in a micro-version of the BASIC language) stored on the memory card – these programs allow you to set the camera to perform a sequence of operations under the control of the program. For example, a camera can be programmed to take multiple pictures for focus bracketing, or take a picture when it detects that something in the field of view moves or changes brightness.
- e. The ability to take a picture, or start a program on the memory card, by sending a signal into the USB port – you can use the USB cable to take a picture remotely.
- f. The ability to do a number of other more useful (and fun) things, such as act as a mini file browser for the memory card, let you play games on the LCD screen, etc.
6. What else should I know?
- Developers around the world are continuing to add new features to CHDK. Because the idea of using the camera’s microprocessor is so flexible, various developers have made different versions of CHDK, and new features continue to be developed – for example, one version of CHDK has features assist in taking stereo photographs, and even allows two cameras to be synchronized to take pictures at the same time (with an accuracy of better than 0.1 milliseconds, providing they are the same camera model).
7. How do I get started with CHDK?
- See CHDK for Dummies and the Firmware Usage page !!!
A sampling of those additional features/functionality.
Main features:
- Save images in RAW format
- Ability to run “Scripts” to automate the camera
- Live histogram (RGB, blended, luminance and for each RGB channel)
- Zebra mode (blinking highlights and shadows to show over/under exposed areas)
- An “always on” full range Battery indicator
- Ability to turn off automatic dark-frame subtraction
- a higher compression movie mode, and double the maximum video file size
- exposure times as long as 65 seconds
- exposure times as little as 1/10,000 of a second
- ability to use the USB port for a remote trigger input
Additional features:
- a depth-of-field (DOF)-calculator
- File browser
- Text reader
- Calendar
- Some fun tools and games
Why would I want to use CHDK?
- To get Raw file capability on cameras that don’t have that ability
- To get the ability to use scripts
- to be able to know the battery status at all times (not just when it’s about to run out of power)
- you want or need any of the other enhancement features that CHDK provides
What are scripts? Scripts are BASIC language programs that give you the ability to control the operation of the camera under program control. They have been used to add or extend the native capability of the camera: more flexible intervalometers, extended-range exposure compensation, extended bracketing ability, lightning photography, etc. See the script pages for more details.
Beyond “Standard” CHDK
Several developers have extended the basic features of CHDK to add additional major functions. You’ll find these extended features in “special builds”.
There are several “Motion Detection” versions available that allow scripts to detect when motion (or any change in light intensity) occurs in one or more predefined regions of the images (the script can then take a photograph, a video, start a timer, etc) and there are some *very* cool applications based on this implementation.
There is a “Stereo Data Maker” (SDM) version, specifically geared to stereo image applications (which also incorporates the Motion Detection routines).
Additional video compression options (more or less), and the ability to go beyond the 1 Gbyte limit.
Use your USB port as a remote control / “cable release”.
See the CHDK Special Builds section at the bottom of the front page for more information, and then follow the links to the developers’ pages for the details.
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- Incredible Shot thanks to CHDK
