Fix sleeping Speedlites with Pocket Wizards

Pocket Wizard & Speedlites that don’t sleep on the job!

Just yesterday I got a call from a photographer friend asking for my advice on stopping his Canon Speedlite from sleeping. He was using a Pocket Wizard plus II to trigger his Speedlite set to a manual power level. The problem was the Speedlite kept going to sleep and needed to be woken up to fire. Not what you need in the middle of a shoot.

So the solution is simple, and works for many of the Canon Speedlites, set the Speedlite’s Custom Function (C.Fn) to disable the auto power off. For most Speedlites this means set C.Fn 01 to 1. The Speedlite 600EX-RT makes setting custom functions simple and provides icons to help you easily see the feature, if you use a recent model Speedlite on the hotshoe of the camera you can also set the custom function from the camera menu.

Speedlite 600EX-RT showing custom function to disable auto power off

C.Fn 1 set to 1 will disable the Speedlite auto power off

The issue is that the Pocket Wizard and virtually all other simple non-E-TTL radio triggers don’t send the keep awake command to the flash, so it assumes you left it switched on in your camera bag again and powers itself down to save your batteries. If you use the flash with Canon pulsed light or radio control, or put it on a Canon camera then it will be kept alive automatically and woken up as needed.

The Speedlite 550EX, 580EX, 580EX II, 600EX, 430Ex and 430EX II all have this custom function C.Fn 01.