I regularly read Lifehacker which often has a great tips and tricks. I noticed they had an article about CHDK firmware for Canon point and shoot cameras, which lead me to another article about the same firmware. I had heard about that earlier, but back then it didn't support my Ixus 850IS. This has apparently changed.
CHDK is a firmware hack for Canon point and shoot cameras that bring quite a few new features to those cameras. Most interesting of those to me are the ability to shoot RAW and bracketing options for shooting images to be used as ingredients of HDR images. So clearly I needed to give it a go.
After uploading the CHDK, I managed to get my Ixus 850IS (aka SD800IS with Digic III processor) to shoot RAW images (CRW), but none of the apps I normally use seemed to be able to read those. Apparently the RAW files produced by CHDK are not compatible with Canon official RAW files, so conversion is required. This was a kicker. dng4ps2 is able to convert Canon cameras RAW files into Digital Negative (DNG) format, which is ideal for this purpose. As it supports Powershot SD800 IS, which is American for Ixus 850 IS, one might thinks that all that is required is to simply select that as a camera from Settings - Camera options and be done with that. One would be wrong. This produces the error message "Can't find camera profile for this file". After some digging out, I found the solution:
- Do NOT select anything under Settings - Camera types
- Under Settings - Camera options, choose "Powershot SD800 IS" and press "copy". Type "Canon DIGITAL IXUS 850 IS" as camera name and "IXUS 850 IS" as short name.
Unfortunately, dng4ps2 loses your camera profile when you close the app, so this step has to be done every time you start the app. Interestingly enough, the created profile seems to be stored in Windows register but it doesn't seem to have any effect whatsoever. Anyway, I can live with that.
XnView, RawTherapee and Gimp armed with Ufraw plugin are also able to read the files and export the files as tiff, however not to DNG. The same goes for Google Picasa, except that it can't create TIFF either.
I did some experiments with bracketing as well. I am using Allbest build of CHDK which has several extra photo operations, one of them being Bracketing in Continuous Mode. Following the guide Bracketing I managed to get it to work. Well, sort of. I couldn't figure out the way to get to the sub menu where I am supposed to be able to adjust the number of bracketed shots. Other than that it seemed fine. There are more advanced options for bracketing involving the use of scripts. To use scripts for creating ingredients of HDR images, see Make ANY Single-Shot Intervalometer into an HDR-Bracketing Script.
As RAW files always, and uncompressed ones in particular, are much larger than jpeg images, I went on bought new SDHC memory card. Only to find out that my memory card reader doesn't want to co-operate with such cards.