Canon Speedlite 600EX-RT & ST-E3-RT firmware update

Canon has issued a note about a firmware update for the Speedlite 600EX-RT and Speedlite Transmitter ST-E3-RT. The update addresses an issue when using 7 or more flashes with linked shooting or wireless flash shooting.

Speedlite 600EX-RT & ST-E3-RT firmware update

Canon UK is offering a free firmware update service at their service centre from 4th January 2016

I just checked all my flashes and every single one needs this update. If you only have a couple of flashes then you are unlikely to have a problem in practice.

I might have seen examples of this issue on some of my workshops where multiple photographers are triggering my flashes. Sometimes the radio just stops working. I’d put it down to automatic channel selection, and often found that using a fixed radio channel eliminated the problem.

The fact that the flashes have to go back to Canon service for the update, makes me wonder why Canon doesn’t make it possible for end-users to update firmware in flashes like they do for their cameras. Some of the third party flashes like the Yongnuo YN600EX-RT include a USB port for firmware updates.

How to find out if your Speedlite flash or transmitter is affected?

Serial number is the key indicator…  the 3rd and 4th number are important

  • Speedlite 600EX-RT [xx01xxxxxx] ~ [xx13xxxxxx]
  • Speedlite Transmitter ST-E3-RT [xx01xxxxxx] ~ [xx03xxxxxx]

Speedlite 600EX-RT

Speedlite Transmitter ST-E3-RT

Speedlite 600EX-RT & Transmitter ST-E3-RT_tcm14-1333172

 Note: If the battery compartment of an affected unit contains the white dot marking illustrated above, the product is NOT affected by the phenomenon described above, even if the serial number is within the ranges mentioned above.


More details can be found on Canon’s support website