Also. Just my opinion: but the day before a paid shoot is not the time to learn your flash radio trigger is incompatible with your flash. Or to try and swallow the whole of off-camera flash knowledge. Rescheduling the shoot or going without off-camera flash may be your best solutions, here. AF assist lamp function on the flash will not work *4 Wireless Slave mode does not support the camera built-in flash as the master function. *5 Since those camera built-in flash have not the master function, they should use a optional master remote unit (e.g. Canon ST-E2) to control wirelessly any slave flash eqipped optical slave recevier. Place an external flash in the camera's hot shoe. Any manual flash should disable the built-in popup flash, but if the hot shoe detector switch isn't working, a Canon "dedicated" (what we now call 'TTL') flash that is powered on should also disable the popup flash. Update from the OP. Looks like I was a bit quick with the question. It is possible to use the flash as a remote commander (master) for slave flashes. Under the 'flash control' menu, you should see settings for the external flash. Make sure it isn't disabled. It is ALSO possible to use the menu buttons on the flash itself to disable the flash (and that overrides the camera settings). Even a very cheap manual flash should confirm that the camera's hot shoe is working and can fire a flash. There is the very remote possibility that your camera could fire a single pin manual flash but not fire a TTL flash with the additional pins in the hot shoe connection, but the chances of that are very slim. 11-20-2020 06:00 PM. Hi --. I recently purchased a Canon EOS RP to replace my Canon Rebel T3i. I just tried to use my Neewer NW670 TTL flash with the EOS RP and it does not fire. To be honest it has been a long time since I used the flash with my Rebel but my recollection is there wasn't any trick to get it to work. Best Detachable Camera Flash for Canon: Canon Speedlite 430EX III-RT. Best Detachable Camera Flash for Nikon: Nikon SB-700 AF Speedlight. Best Detachable Camera Flash for Sony: Sony HVL-F32M External Flash. Best Overall Third-Party Camera Flash: Westcott FJ80 II Speedlight. Best Budget Third-Party Camera Flash: Bolt VD-420 Manual Flash. Even RP has the same sensor and max shutter speed as 6DII. It does not mean that the high speed sync will work. I have tried all M and ttl and ended up with similar results, i.e., clear banding (90% picture dark and top 10% bright) in my pictures as soon as shutter speed exceeds 1/200. Firmware for camera, flash and triggers is updated. Even when it’s not set to contribute real light to scene, my pop-up flash on the Canon 7D forces my camera to report “Busy” while it cools down. It prevents me from taking another photo for 10 to 20 seconds at a time. This is especially frustrating as I’m not asking the pop-up flash to fire at full strength. EOS 6D Mark II stopped recognizing Vello wireless remote in Camera Accessories 10-25-2023; Visualizer RE-450x - Working with Windows 10 in Camera Software 10-23-2023; PowerShot G7 X Mark II Flash Bulb Not Working in Point & Shoot Digital Cameras 10-22-2023; Help troubleshoot issues with Rebel T6 webcam. in Camera Software 10-21-2023 clpPa.