Canon EOS-1D X firmware squashes bugs, fixes AF problem for some bodies in the process

Canon USA has issued updated firmware for its EOS-1D X digital SLR, fixing a couple of problems and adding one new feature.

Canon EOS-1D X firmware v1.2.1 adds a new function to the Recording Card Image Size Setting option, found on tab four of the Custom Functions menu. The "Disable image size button" option deactivated this button, located on the camera's rear panel adjacent to the secondary information LCD. If your workflow means that you never change the image size, this is a great way to prevents accidental changes to the image size setting caused by the button being bumped, most likely while hanging from a shoulder strap.

The update also corrects problems with the Err 70 and Err 80 error messages being shown in certain, unidentified shooting situations. 

You'll also want to update if you've been having any difficulties with shooting using center-point autofocus at smaller apertures. Last October, Canon released updated firmware for its EOS-1D X professional digital SLR, allowing use of apertures down to f/8, great news for wildlife photographers, among others, as it meant you could still autofocus with a super-telephoto lens mounted on an extender.

Unfortunately, while Canon had started applying the updated firmware to cameras fresh off the production line, it seems there was a glitch in the variant used by the factory. Although it carried the same version number 1.1.1 as that provided on Canon's website for existing owners to install on their own bodies (and used at service centers, if you returned your camera for service), a product advisory from Canon said that on some EOS-1D X bodies, the factory-installed v1.1.1 firmware didn't allow autofocus at f/8.

 

If your EOS-1D X is on firmware v1.1.1 and the serial number contains a four or five as the sixth digit...

 

...then check for a white dot in the position shown above. If it's missing, you'll need to update your firmware.

This was true, said Canon, of some bodies where the sixth digit of the serial number was a four or five. If your serial number matches that pattern, you can tell whether your particular body is affected by opening the battery compartment. If there's a small white dot at the top of the battery compartment, then your camera isn't affected by the issue.

If, however, the serial number matches and the white dot is missing, then your camera is affected. The great news is that fixing the problem is extremely simple: download the latest firmware update, and apply it yourself. This will overwrite the factory-installed variant, and cure the problem. Then mount your lens and extender, and go try your newfound f/8 autofocus capability!

(And yes, we initially missed that the service advisory was published a little over a month ago; it just came to our attention today. Turns out the just-released firmware update was newer. Thanks to @jeffersonite in the comments for pointing this out!)