How to do a Canon firmware downgrade
(works for upgrade too)
There seems to be a lot of FUD (Fear Uncertainty and Doubt) about changing the firmware on your camera, especially for uninitiated Magic Lantern users who are pointed to a website in Hungary run a guy who goes by the name of Pelican to get older firmware versions. Nothing against Hungary (I'm half-Hungarian) or Pelicans (I live at the beach) but a little anxiety is understandable.
Once you realize that it is extremely unlikely that someone created a FIR file that will cause your camera to send banking information to international cyber terrorists, download the file onto an SD card.
Firmware updates are generally posted in some sort of compressed format often along with the instructions on how to run the firmware update. If you are on a Mac and can only find a Windows version, don't panic. The *.FIR file runs on the camera so it doesn't matter which computer platform you are using. Of course you might download something that looks like this on your Mac:
Again, don't panic. This is a self extracting Windows archive and you can use Stuffit Expander which is in the Applications/Utilities folder of every Mac to expand the archive file.
I've got several cameras and like to play around with different versions of Magic Lantern so I put all of my FIR files on a single card. Make sure that the card doesn't have the boot flag enabled because if your camera also has the boot flag enabled it will just hang when you start up the camera unless you also add a ML autoexec.bin file and then it won't work on multiple platforms. In other words, this will be your dedicated firmware card.
Those CCF14* firmware files are for the 700D/T5i, yeah I know it isn't obvious. And just in case you're thinking it, no the 5D3 firmware won't install on the EOSM. Only the valid choices will show up.
Now when you run the firmware update from the Canon menu using this card, remembering to have the camera in Manual and Still Picture mode, it will run the firmware update process--even if you are doing a firmware downdate. (Is there such a word?) The firmware update will not run if you don't have enough juice left in the battery and some external power adapters supply barely enough voltage to run the camera so it might not work. Best be safe and top off your battery first.
End of tutorial.Not!
Firmware versions in the x.3.x series (currently only affecting 5D3) won't let you downgrade to a prior series. In other words, you can go from 1.3.4 to 1.3.3 but if there is a 1.2.3 or a 1.1.3 firmware on your card you'll get this message:
It is not quite that easy with some of the latest Canon firmware updates. There are warnings about not being able to downgrade and rumors that you need some older 2.x version of Canon EOS Utility to do the downgrade but I found that is not really the case. If you happen to have one of those irrevocable firmware versions on your camera you can use whatever version of EOS Utility you have. Make sure to put a copy of the FIR file on your computer because you'll have to point to it with EOS Utility. Also make sure your camera is in Manual and Still Picture mode or EOS Utility will refuse to do the firmware update.
HA! Just noticed that "WTF Captions" item. Who says Canon engineers don't have a sense of humor?
Ok--back to doing this. You need to have a card in your camera so let's use that dedicated SD card with all the various versions. Here we go:
Hey, what just happened? EOS Utility just transferred the firmware update from your computer onto the card in your camera and you can now disconnect the USB cable. The rest is exactly the same as before. In fact if you have multiple firmware versions on your card you can now have a second chance to decide which version you want to install.
Interestingly the firmware update will not change the status of the camera boot flag so you won't have to re-install ML. If you are curious what a new firmware version looks like, use the Portable ROM dumper
and run the ROM1.BIN file through a disassembler and...I'm getting off topic here, porting a firmware update to ML is another tutorial.