Canon U.S.A has announced a firmware update is being worked on to address the ‘phenomenon’ wherein its EOS-1D X Mark III DSLR camera will lock up under certain conditions.

Previously, we reported on a number of incidents wherein Canon’s latest flagship DSLR would lock up when pressing down the shutter in certain modes. While the exact cause remains unconfirmed, Canon’s changelog for the forthcoming firmware update suggests the bug is caused when the electronic level is turned on in the viewfinder display. Below is the exact text from Canon:

‘The phenomenon may occur when the camera is being used with the electronic level set to “Show” in the viewfinder display. In rare cases, the camera may not perform as it was designed to when operating the AF-ON button or shutter button.’

Note the magnified section, which appears to show a part of the interface used for the OVF level function. This would suggest Canon's diagnosis of the level feature causing the lockups is accurate for at least one of the original cases we reported on.

Below is a video provided by DPReview reader Hamilton Pytluk, who showed how the bug was affecting shooting. At the time of our initial coverage, it wasn’t known what was causing this issue, but if you look closely (it’s only visible for a few frames), it does appear as though Pytluk had the level showing in the optical viewfinder, which Canon is suggesting is the problem causing the lockups.

Canon says the firmware update will be available in ‘early April,’ but in the meantime, it’s possible to prevent the locking by hiding the ‘Electronic level’ within the ‘Viewfinder display’ sub-menu, as shown in the below menu screenshots provided by Canon. Canon has provided a guide to disabling the viewfinder on its update page.

We will cover the release when the firmware is published, but you can also keep an eye out on the Canon EOS-1D X Mark III product support page.