Firmware
Firmware Version 1.1.0 incorporates the following improvements and fixes:

1. Improves writing/reading speeds when using UDMA 7-compatible CF cards.

2. Fixes a phenomenon where the ability to shoot movies may be stopped under the following conditions:

   • When using high-capacity (32 GB or greater) CF cards with little available space remaining and the user attempts to start shooting movies; or
   • When the camera’s battery is removed and reinserted into the camera and the user immediately attempts to start shooting movies.

3. Corrects misspellings in the menu screens displayed in Arabic and Portuguese languages (applies to models outside of the Japanese market only).

The new Firmware Version 1.1.0 can be downloaded by clicking here.

Firmware Version 1.1.0 is for cameras with firmware up to Version 1.0.8. If the camera's firmware is already Version 1.1.0, it is not necessary to update the firmware.
Note that cameras with the Version 1.1.0 and Version 1.0.8 firmware cannot be downgraded to a previous firmware version (such as Version 1.0.6 or earlier).

This information is for residents of the United States and Puerto Rico only. If you do not reside in the USA or Puerto Rico, please contact the Canon Customer Support Center in your region. Please register your EOS 1D Mark IV. By registering, we will be able to notify you via email when future firmware updates become available for download.  If you already registered, please ensure you are opted-in to receive the notification.

Thank you,
Customer Support Operations
Canon U.S.A., Inc.

Contact Information for Inquiries
Canon Customer Support Center
Phone:  1-800-OK-CANON
             1-800-652-2666
TDD:    1-866-251-3752
Email: carecenter@cits.canon.com
Support options and hours of operation: www.usa.canon.com/support