topic Re: Canon R5 mark II with flash how to remove pre flash? in EOS DSLR & Mirrorless Cameras

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

ElaTatiana — Sun, 21 Dec 2025 19:56:13 GMT

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..

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

SignifDigits — Sun, 21 Dec 2025 20:54:07 GMT

I've really got no idea to the answer, but I'm dropping a note here to let you know that I'm sure someone here will. I will ask for more details as that will be helpful to whoever does diagnose the problem:

What flash are you using? What mode? A quick search gave this answer "To disable the pre-flash ... you need to turn off features like red eye reduction and potentially set your flash mode to Manual (M) if using a speedlite, as E-TTL (Automatic) always uses a pre-flash"

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

ElaTatiana — Sun, 21 Dec 2025 20:59:40 GMT

Thank you for your suggestions. I don't have this option red eye reduction in this model. I am 100% sure it is some setting in camera as I have tried serval different flashes and all fired twice in both modes manual and ttl. I also checked the same settings and flash with my older canon R5 and its working fine.Thank you so much for your suggestions, I really appreciate it. I don’t seem to have a red-eye reduction option on this model. I’m fairly sure it’s a camera setting, since I’ve tried several different flashes and they all fire twice in both Manual and TTL modes. I also checked the same flash and similar settings on my older Canon R5, and everything works fine there. Thanks again for taking the time to help 🙏

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

deebatman316 — Sun, 21 Dec 2025 21:02:33 GMT

Full Frame bodies & the EOS R7 DO NOT have a red eye reduction setting this is due to lacking a built in flash. This only applies to APS-C cameras with a built in flash. Manual Flash has no pre-flash because you manually set the flash power.

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

SignifDigits — Sun, 21 Dec 2025 21:07:40 GMT

Glad to answer, sorry it wasn't more helpful and more authoritative. I've only got the Someone will probably drop in and know the real answer - hope so. I do know the R5 Mark ii supports a the newer Canon flash hotshoe that syncs better with the electronic shutter. For my R6 Mark ii I have to use manual shutter, not electronic. Have you tried the various shutter modes to confirm the behavior in all shutter modes?

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

SignifDigits — Sun, 21 Dec 2025 21:10:22 GMT

I should have said "...I've only got the R6 Mark ii to explore.." and "...I have to use manual shutter with my old Speedlite..."

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

deebatman316 — Sun, 21 Dec 2025 21:14:06 GMT

Hi @ElaTatiana welcome to the forums. What are your shooting conditions like. Is the ambient lighting too low for AF to work. Or is the camera struggling to acquire focus in low light? What mode are you shooting in on the top mode dial ie M, Av, Tv, P, A+ or Fv Modes. Was your older Canon body a DSLR or EOS 35mm AF SLR by any chance? If so those those cameras use a different method to help the camera AF in low light. What flash are you using by any chance is this a Canon Speedlite or a 3rd Party Flash by any chance. When does this "pre-flash" happen. Does it happen when the shutter button is pressed half way or the back button focus button ("*" or "AF-ON" button is configured for AF Start) is pressed. What lens are you using the full name is necessary also are you using native RF lenses. Or adapted EF lenses if so what mount adapter are you using. Is this the Canon brand adapter or is this a 3rd Party mount adapter.

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

ElaTatiana — Sun, 21 Dec 2025 21:15:11 GMT

That was very helpful. I just tried and it was the electronic shutter 🤦🏻

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

SignifDigits — Sun, 21 Dec 2025 21:16:21 GMT

grrr... I need to slow down "...manual shutter.." should have been "...mechanical or elect. first curtain..." But I still don't get a pre-flash. My old Speedlite just refuses to fire with electronic shutter.

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

deebatman316 — Sun, 21 Dec 2025 21:19:53 GMT

@SignifDigits only the EOS R3, EOS R1 & EOS R5 Mark II can fire a speedlite with the camera set to the fully electronic shutter. No other Canon mirrorless body can do this. This is a limitation of the image sensor's read out speed. With mirrorless cameras the speedlite has to pulse as if the speedlite is set to HSS to prevent banding.

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

SignifDigits — Sun, 21 Dec 2025 21:23:59 GMT

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.

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

ElaTatiana — Sun, 21 Dec 2025 21:27:05 GMT

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 🙏

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

SignifDigits — Sun, 21 Dec 2025 21:32:58 GMT

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

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

deebatman316 — Sun, 21 Dec 2025 21:43:07 GMT

@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.

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

deebatman316 — Sun, 21 Dec 2025 21:49:33 GMT

@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.

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

SignifDigits — Mon, 22 Dec 2025 02:49:29 GMT

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.

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

deebatman316 — Mon, 22 Dec 2025 03:33:53 GMT

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.