I was thoroughly drawn in by the Amazon ‘Black Friday’ event last week, buying both a phone and a camera, against my better judgement and to the disgust of my bank manager. While trying to suppress my buyer’s remorse by searching the internet for all the marvellous capabilities of my soon-to-arrive devices, I noticed that the camera, a Canon Powershot SX220 HS, was one of the models capable of running a piece of open source software called CHDK released under the GNU GPLv2. This program leverages the fact that the camera will execute anything that look even remotely like a firmware update that is located on its SD card without requiring a digital signature, allowing an adjunct to the device’s firmware to be executed every time it starts up. You can even place the program on the SD card and select whether it is booted or not by changing the ‘write protect’ switch on the card.
Once the software is booted the user has access to an almost ridiculously long list of tweaks and features, including saving pictures as ‘RAW’ (meaning that the data from the camera’s sensor is saved to the card unaltered, rather than being crushed down into a smaller JPEG file), greater control over exposure times and the ability to construct more complicated ‘bracketing’, meaning that a series of shots can be taken with differing focal lengths or levels of white balance, allowing creation of HDR images and focus-stacked images. Even more geektastic is the ability to script the functionality of the camera using UBASIC or LUA, allowing a user to build functionality like time lapse photography and the taking of pictures only when motion is detected.
One question that remained with me, even as I contemplated spending more unwise pounds, was what Canon’s attitude was to this project. After all, some of the functionality that CHDK contains can be obtained from Canon in its more expensive models. They could close the technical loophole that allows the additional software to be run fairly easily, so one must assume that they do not see the existence of open source expansions of their equipment as a threat to their business model. Might they even see it as a selling point? Certainly it seems that running CHDK is likely to void your warranty, so perhaps the existence of a group of customers who opt out of expensive warranty provision is seen as a bonus.
Discovering this went some way towards alleviating the guilt of my spending. After all, I had got a large amount of functionality at essentially half price. But… if you want to run long scripts then you really need the attachment that lets the camera run off mains power. That’s not such a bargain. I could also probably do with a better tripod… Oh dear…