This firmware update incorporates the following improvements:

1. Fixes the phenomenon of large image files (1.7GB) being created.
2. Improves the brightness of the LCD monitor.
3. Fixes an operational abnormality in the AEB (Auto Exposure Bracketing) shooting.
4. Fixes the mistakes in the Swedish-language MENU displays.

This firmware update applies to cameras with firmware versions 1.0.1 installed. By installing this update, the phenomena will be fixed, and the affected cameras can be used without these problems. If your camera’s firmware is already version 1.0.3, it is not necessary to perform this update.

Following the follow simple steps for the update :

1. Formatted CF card in 5D (not computer)
2. Put card in computer
3. Downloaded file (link above)
4. Unzipped it
5. Copying *.fir to root of card
6. Removed lens from 5D
7. Used battery pack (with two newly charged, fresh batteries)
8. Inserted card in 5D
9. Put 5D in P mode
10. Turned 5D on
11. Used Menu to find Firmware
12. Followed screens to upgrade
13. About 3 - 4 minutes it was done.

Download : Canon 5D firmware update version 1.0.3