I got most of this info from which includes instructions for doing the same thing in Windows. The latest updater (281) doesn’t contain the ist file, so we have to install the old one first, then update. Once that is finished you can run the latest updater and it will recognize your previous install. Go to Contents/Resources/ and delete ist. Then right click and go to Show Package Contents. Now extract the 261 updater and copy out UpdateInstaller to your Desktop. Download the updater here (I think all cameras have the same EOS Utility) and grab the latest version as well while you’re at it. As of this writing the 2.61 updater works. This will only work with the older versions. We can get around their retardedness (it’s a word, shut it) by editing their updater. The only conclusion I can come up with is that they are completely fucking retarded. It’s not like you can use it without buying one of their cameras. I’m not sure why Canon wants to make it so hard to use their software without the original CD.
For that you need the CD that came with your camera. After checking Canon’s website I found that they only offer updates, no actual installer. I recently tried installing the Canon EOS Utility on my new laptop. Since I originally wrote this post there have been several new versions of the software that require different instructions.
