There might be some rare cases forcing you to rollback to an older firmware version on your Canon camera. Here is a quick and dirty trick to do it.
This is not a method endorsed by Canon. It just works and might well not work in the future. You have been warned, proceed at your own discretion.
- Copy firmware 1.5.0 on one card, copy firmware 1.4.0 on a second card
- Insert the card with firmware 1.5.0 into the card slot
- Navigate to the firmware update setting in the camera menu
- Press “okay”, and as quick as you can open the battery door of the camera
- Pull the card with firmware 1.5.0 and insert the card containing firmware 1.4.0
- Close the battery door and turn the camera back on
- The camera should now automagically do the update by downgrading from firmware 1.5.0 to 1.4.0
And here is the video.
Be aware that hacks like this one always come with an intrinsic risk of damaging your camera. If you feel you have an issue after a firmware update, in most cases it might be more appropriate to wait for the next firmware version instead of rolling back. In the past, when there have been issues with a firmware release, Canon has always been very swift in releasing a fix.