Recently I updated firmware of my Godox X1T-C remote trigger to be able to use it with Canon EOS400D which have trimmed down flashlight hotshoe (trigger pin is missing). Now the trigger is working and can be used with all kind of legacy flashlights (in manual mode only) but the assist beam is not showing up anymore. Does anybody experianced the same issue or does anybody know what may be the reason behind this?
If you have changed the AF mode from 'One Shot AF' to 'AI Servo AF', the assist beam will not operate with any flashes or triggers that have assiste beams, including Canon external flashes and even the popup flashes on Canon cameras that have them.
In order to use an AF assist light, the AF mode must be operating in 'One Shot AF' mode.
If you are using 'AI Focus AF', where the camera initially uses 'One Shot AF' but will switch to 'AI Servo AF' if it senses the subject distance has changed, then when the camera is initially in 'One Shot AF' mode the assist beam/light will operate until focus is locked, but if/when the camera switches to 'AI Servo AF' mode then the assist beam/light will no longer operate.