MacOS X 10.4.3 promised updated raw support for digital cameras. I happen to have one that can write raw files, but wasn't recognised by 10.4.2 and earlier. I hoped the 10.4.3 update would fix this, since Apple has announced that Aperture, their upcoming photo editor app, would support the 350D.
I was, unfortunately, disappointed.
Well, the list of supported cameras says that Aperture would support the Digital Rebel XT. It's essentially the same camera as the 350D, but named for an american market. So in most cases, 350D == Rebel XT. Not in this case, though.
I found this webpage, explaining how to make OSX like the 350D. Apparently, OSX determines support for CR2 files by the model name of the camera that it contains. So it now supports the Digital Rebel XT, but not the 350D (or the Kiss Digital N, the Japanese name for the same camera). This means support is easily added by editing the Property List file containing the definitions.
The page shows you how to fix it by duplicating the 300D's info in a Raw.plist file, but doing it just like that causes images to be mostly very green. An addition was made to the page that is supposed to fix it by multiplying pixel values, but I find it's too yellow because the multiplication values were taken from the info for a Compact Camera. They are very sensor-dependent, and there is absolutely no comparison between the 350D's sensor (or any digital SLR's, for that matter) and a compact camera. The real fix, making the images look just like they should, is to just multiply the Red and Blue pixel values by two.
So after you paste in the XML-snipped from the webpage referenced above, change the three lines that read 'premul' like so:
<key>premul0</key> <real>2.00</real> <key>premul1</key> <real>1.00</real> <key>premul2</key> <real>2.00</real>
The technical background for this is that the sensor in the 350D (and other DSLRs) contain twice as many green pixels as they do red and blue ones. Apparently the sensors in compact cameras are different.
Update: yes, this makes Aperture work with the 350D, too.Update again: MacOS X 10.4.4 includes built-in support for the Canon 350D and KISS Digital n.