Main Builds » 5D Mark III 1.2.3

Latest Build (2018-07-03 00:12)



Firmware 1.2.3 is required if need any of those features from Canon:
  • clean HDMI out
  • dual monitor support (internal+external)
  • AF at f/8 with teleconverters

If you don't need anything from the above list, please consider downgrading to 1.1.3.

A few ML features are not compatible with 1.2.3 (see the Features tab and the 1.1.3 forum thread). If you need any of these features, you will have to downgrade to 1.1.3.

Recommended card setup

  • install Magic Lantern to an SD card
  • use CF card(s) for taking pictures or recording videos
However, any card configuration may be used.


  1. Make sure you are running Canon firmware 1.2.3.
    If you are running 1.3.3, 1.3.4 or 1.3.5, you can downgrade with EOS Utility (instructions).
    Downgrading from 1.3.6 is possible, but tricky.

    Whatever you do, do not remove the battery in the middle of a firmware update!

    Method B (recommended, one single card required, either SD or CF, source, discussion):
    • copy firmware 1.3.6 (5D300136.FIR) to the card
    • launch Update Firmware from Canon menu, click OK
    • open the battery door ASAP, but don't remove the battery!
      • if you did it right, the camera will turn off (wait for a few seconds to make sure it's really off)
      • if you see the Firmware Update Program Loading screen, it means you have opened the battery door a bit too late; wait until the camera turns off and try again!
    • open the card door and remove the card from the camera (do not close the battery door; also leave the power switch on; the camera should stay off)
    • copy firmware 1.2.3 (5D300123.FIR) to the card
    • put the card back into the camera, close the card door
      • you may leave the original 1.3.6 FIR on the card, or you may delete it; doesn't matter
    • close the battery door; you should see the Firmware Update Program Loading screen
      • if you get an error message at this step, remove the battery and reboot
    • confirm the firmware downgrade from 1.3.6 to 1.2.3
    • a successful downgrade should take about 4 minutes.

    Method A (not recommended, two SD cards required, not CF, source, video tutorial):
    • prepare two SD cards:
      • one with firmware 1.3.6 (5D300136.FIR)
      • one with firmware 1.2.3 (5D300123.FIR)
    • insert the 1.3.6 SD card in the camera
    • launch Update Firmware from Canon menu, click OK
    • you should see the Firmware Update Program Loading screen
    • wait until the card LED goes off
    • swap the cards quickly (you have about 10 seconds to perform this trick)
    • confirm the firmware downgrade from 1.3.6 to 1.2.3
    • if the camera reboots into 1.3.6 after downgrading, please try the other method (details)
    • note: CF cards are not recommended for this procedure, as they are accessed by Canon bootloader without LED activity, so you won't know when to swap them.

  2. Once you have the correct Canon firmware:
    • Format the card from the camera.
    • Unzip the archive and copy ML files to the memory card.
    • Run the Firmware Update process from Canon menu.

      This procedure will enable the BOOTDISK flag in your camera's Flash ROM, allowing it to load and execute custom code from the memory card. A copy of the original (unmodified) ROM contents will be saved to the card.

      Magic Lantern will run from this card; it won't replace your original firmware.

  3. After installation, please copy your ROM backup files (ML/LOGS/ROM*.BIN on the card) to a safe place.
Detailed instructions on the wiki. Please don't forget to check the FAQ and the user guide.


From camera:
  1. Run Firmware Update from your ML card.
  2. Follow the on-screen instructions, including the fine print.

    This procedure disables the BOOTDISK flag. You will no longer be able to run Magic Lantern, unless you reinstall it.

    Some settings changed by Magic Lantern might be persistent; this procedure will not reset them. To restore the camera to factory state, you may also want to clear all camera settings and custom functions from Canon menu.

From one card:
  • Canon menu: Format card, remove Magic Lantern.
  • This procedure does not disable the BOOTDISK flag. With this method, you will still be able to run Magic Lantern from other cards.
  • Never delete the Magic Lantern files from the card! Format the card instead.

Camera doesn't boot?

  1. Remove battery, remove card.
  2. Put battery back, close card and battery covers.
  3. Start the camera without card.
    • » Did it work? Format the card, reinstall Magic Lantern.
    • » Still not working? Double-check battery and card doors, run the diagnostic tools and get in touch with us.

Troubleshooting tips

  • If your camera locks up, remove the battery and reboot.
  • Make sure you have a backup card without Magic Lantern on it (just in case).
  • To restore ML defaults: Prefs → Config files.
  • To see what settings you have changed from ML defaults: Modified (Δ) menu.
  • To disable Magic Lantern temporarily: press and hold SET at startup.

Older Builds (hide) (show details)

Test results: 7 passed, 0 failed.

Test results: 7 passed, 0 failed.

Test results: 6 passed, 0 failed.

2018-07-03 00:12 - Build failed!

2018-07-03 00:12 - Build failed!

2018-07-03 00:12 - Build failed!

Magic Lantern is not approved nor endorsed by Canon in any way, and using it will probably void your warranty.
We are not responsible for any damages to your camera.

Copyright (C) 2009-2018 Magic Lantern Development Team

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.