There’s a lot of mis-information, mis-conceptions and questions about the “CHDK hack” available for many canon cameras. While I’m no expert I am a very satisfied user and I did extensive research prior to loading it. Hopefully what follows will provide some useful information. Most of it is either taken from or paraphrased from the link at the end.
For many canon owners there is a possibility to get additional functionality out of their camera.
Commonly referred to as the “CHDK HACK”, in reality CHDK is a firmware enhancement that operates on a number of Canon cameras. CHDK gets loaded into your camera's memory upon boot up (either manually or automatically). It resides on the SD card, taking up around 320k of space. It provides additional functionality beyond that currently provided by the native camera firmware. CHDK is not a permanent firmware upgrade-you decide how it is loaded (manually or automatically) and you can always easily remove it.
How does it work?
First you have to understand, it’s cost effective for Canon to have one processor serve its whole product line. Economies of scale and all that. The current processor is the DIGIC III. The previous processor was, not surprisingly, the DIGIC II. Almost all Canon cameras sold today have either the DIGIC II or III processor as their “brain (top of the line DSLRs may have two processors), with the DIGIC III phasing out the DIGIC II.
These processors are pretty impressive chips and Canon “turns off” certain features on certain cameras depending where they stand in the product line. CHDK simply “turns them back on”. CHDK can not “make” the processor do anything it wasn’t designed to do.
What enhancements? (Note-some of these may already be available on some products)
Save images in RAW format (also saves a copy of the picture in jpg)
Ability to run "Scripts" to automate the camera (ex- time lapse photography)
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 (you can chose percent of battery life remaining or actual volts left on batteries)
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
a depth-of-field (DOF)-calculator
File browser
Text reader (with auto scrolling feature)
Calendar
Some tools and games
Cameras supported by the enhancement: a560,a570, a610, a620, a630, a640, a700, a710, s2, s3, g7, sd500, sd700. The list is growing all the time. For purely educational purposes, I loaded CHDK on my a710 and it delivered all that it promised. RAW gets all the attention but many times I find myself turning RAW off but I always use the live histogram, zebra mode, and the battery indicator is sweet! To toggle RAW on and off you must use the print button and my underwater housing does not have a button that corresponds to the print button (probably because they don’t make a housing for my printer) so you can’t toggle RAW on and off underwater, you need to set it on or off before closing the housing.
As stated above – I am a very happy user of CHDK. However, I make no claims about the validity of these enhancements. While many have used these enhancements with no problems, anyone attempting to do so should be made aware they may, in fact, be voiding their warranty by doing so.
For much more information on the subject, visit:
CHDK - CHDK Wiki
Linear Mode
