Canon R5 mark II with flash how to remove pre flash?

[ElaTatiana]

Hey guys, I could really use some technical advice. I’m using the Canon R5 Mark II with flash, and I’m noticing a pre-flash happening in both Manual and TTL modes. Does anyone know how to disable this? I didn’t have this issue with my older Canon body, and I haven’t been able to find clear info about it online..

[SignifDigits]

Thanks  deebatman316!  That makes sense.  I'm sure the manual states this, but I found out by trial and error on my R6 Mark ii recently.  I really never shoot with a flash so it didn't matter much to me.  Recently, when I got my old EL-100 out when I reorganizing bags I decided I should at least make sure it still worked.  Thus, my experimentation.

[ElaTatiana · Accepted solution]

Thank you so much for getting back to me. With the help of someone earlier, I was able to figure out that the issue was related to the electronic shutter release. Once I switched to first-curtain shutter, the flash started firing as it should.
It seems that both the electronic and full mechanical shutter modes were causing the flash to fire twice. For reference, I shoot in manual mode with an RF 24–70mm lens and use Godox flashes, both with and without a trigger. The double flash was happening when I fully pressed the shutter button.
My previous camera was the Canon R5, which didn’t have this behavior. Thanks again to everyone for the help I really appreciate it 🙏

[SignifDigits]

ElaTatiana, thanks for participating and especially thanks for letting us know what worked.

[deebatman316]

@SignifDigits there's also another time the speedlite can produce what looks like a pre-flash. This is called an "AF Assist Beam". Under difficult lighting with the camera set to One Shot AF the speedlite will switch to Intermittent Flash Firing Mode to provide an AF Assist Beam. All of Canon's own speedlites all the way back to the very first E-TTL compatible speedlite will provide an AF Assist Beam this way on EOS R series cameras (EXCEPT the EOS R100). Note depending on the AMBIENT LIGHTING an LED AF Assist Beam maybe projected by CAMERA instead of Intermittent Flash Firing from the speedlite. The EL-5's LED AF Assist Beam works differently when used on the EOS R3, EOS R7 & EOS R10. On these cameras the LED AF Assist Beam is projected at FULL BRIGHTNESS ONLY. If the ambient is too low the speedlite will switch to Intermittent Flash Firing or the camera body will emit an LED AF Assist Beam. On other multi function hot shoe cameras such as the EOS R5 Mark II the camera can adjust the brightness of the LED AF Assist Beam depending on the Ambient Lighting. The speedlite will NOT switch to Intermittent Flash Firing. If the speedlite overheats the LED AF Assist Beam automatically reduces brightness or switches to Intermittent Flash Firing for SAFETY. In this case the camera can also project an LED AF Assist Beam.

[deebatman316]

@ElaTatiana were you using both E-TTL & 2nd/ Rear Curtain Sync with the shutter speed set at or below 1/25th sec. If so the first flash was the E-TTL pre-flash then the 2nd flash was the actual flash for the exposure. Also do you really mean first curtain shutter or electronic shutter? This wouldn't have an effect on which shutter mode being used.

[SignifDigits]

Wow.  SO knowledgeable debatman316.  Thanks for stepping in and sharing!  I think/suspect that the camera is also smart enough to know that the lens is blocking the camera assist beam, as I notice that option is greyed out when my lenses are covering it up.

[deebatman316]

I’ve also found out this is AF motor type dependent too. If the lens uses a fast motor. Such as Ring Type, Nano USM or VCM. The speedlite will fire continuously (Intermittent Flash Firing Mode). But slower motor lenses ie Arc Form Drive, Micro Motor, Micro USM or STM. Will cause the camera to try the camera body AF Assist Beam first. If that’s not helping then the speedlite emits the beam. Note there is NO user configuration to make the IR beam work if the speedlite has one. In 2007 Canon not only made hardware changes to speedlites and camera bodies. They introduced what we know as the speedlite control menu. Older speedlites weren’t compatible with it. But the then new 580EX II Speedlite was. You could control the speedlite’s settings from the camera menu. When this change was made Canon brought out 2 new AF Assist Beam types. These 2 still exist today and are still in use today. Those are LED and Intermittent Flash Firing. These AF Assist Beam types are INCOMPATIBLE with pre-2007 DSLRs and EOS AF SLRs. The reason why Intermittent Flash works with all of Canon’s speedlites are simple. The speedlite already has the hardware to support it. The older camera bodies lack the hardware to support. I have multiple articles about flashes under my PKB. Older flashes can show basic settings in the camera’s Flash Function menu. But these options are grayed or missing. You must change them directly on the speedlite. Unless the speedlite lacks an LCD screen to do so like my old 420EX released in 2000. The camera retains the ability to set rear curtain sync. For certain older speedlites which lack an LCD screen to set this function. This can only be set if the HSS sync switch is set to off. This overrides the body’s curtain sync option. With older speedlites all the camera menu can show you is. What your current flash settings are. The example picture below is my 550EX mounted on my EOS 5D Mark IV.