I just grabbed the 2.0.4 version of the Canon 5d Mark II firmware and these are the steps it took to install it using GNU/Linux.

1. Fetch the Mac OS X dmg version of the firmware
2. Install dmg2img
3. Convert the DMG to an IMG file

   dmg2img eos5d2204.dmg

4. mount it temporarily

   mount -t hfs -o loop eos5d2204.dmg /mnt/tmp

5. insert a CF card and note where it’s mounted
6. Copy it to the card:

   cp /mnt/tmp/5d200204.fir /path/to/CF/card

See linux is easy ;)

Actually, would it be a pain for Canon to just release the firmware in a zip file? I’d think that would work for everybody, but I’m guessing that they are relying on a possible built in checksumming in a DMG and their exe files? I’m not sure about the checksum, but that would make sense.

For those curious, here is the sha256 checksum of the 5d200204.fir file the above process created:

424b1990b52af12748f9675c2085e58949ac3fc682b1e61717c2218f89cdd149  5d200204.fir

The new firmware adds a bunch more features to the video feature set of the camera, including various frame rate options. For more info see canon’s site.