The today freshly announced Canon R6 Mark III might fit in R6 II underwater housings and natevily offers now X-Sync speed of 1/320 putting it close to this charming Sony A1 feature 🤩

https://m.dpreview.com/reviews/canon-eos-r6-iii-initial-review

Flash sync speed	1/320 sec

15 hours ago, Adventurer said:

The today freshly announced Canon R6 Mark III might fit in R6 II underwater housings and natevily offers now X-Sync speed of 1/320 putting it close to this charming Sony A1 feature 🤩

https://m.dpreview.com/reviews/canon-eos-r6-iii-initial-review

Flash sync speed	1/320 sec

It will be close, comparative views at Camera decision with III copy and pasted over II at 50% opacity on left.

https://cameradecision.com/compare/Canon-EOS-R6-Mark-III-vs-Canon-EOS-R6-Mark-II

The top dials seem to have moved very slightly. but everything else is very close.

8 hours ago, Chris Ross said:

The top dials seem to have moved very slightly. but everything else is very close.

I have the impression, this is just a slight perspective shift resulting from two different photos taken.

Putting myself in Canon's product management shoes, I would try to utilise the same body tooling + parts when the design change and upgrades are all internal. So I conclude the camera body is very likely to fit in all existing R6 II underwater housings in the market.

Let's wait and see for the confirmation.

3 hours ago, Adventurer said:

I have the impression, this is just a slight perspective shift resulting from two different photos taken.

Putting myself in Canon's product management shoes, I would try to utilise the same body tooling + parts when the design change and upgrades are all internal. So I conclude the camera body is very likely to fit in all existing R6 II underwater housings in the market.

Let's wait and see for the confirmation.

Agree it has a good chance of working - we'll wait and see what the housing makers do - maybe a R6 II user will take a chance and try a MkIII in their housing for us?

I made the same comparison with cameradecision visuals and apart for the on/off switch also saw that the joystick is a bit more sticking out.

I am going to check whether this prevents any movement and will keep you updated.

I might be an early adopter as these were the specs I was expecting from my next camera when I was in the market. However, I settled with the R6 II as there was no such offering.

Additionally, I still believe that the R6 II is an excellent camera even though the R6 III is out.

The new x-sync speed is a real treat and makes me consider it as another camera body next to R6II. The additional megapixel count raises the attractiveness even more.

For photography, it is basically the same camera except for the 32.5 MP sensor upgrade where you can get more sharpness and more cropping ability.

I think there is a misunderstanding with the sync speed of the camera and I had a look at the detailed specs. The x-sync speed of 1/320 applies for cropped resolution which is not very useful:

This is the same for R6 II for full frame resolution.

There is a slight banding issue visible when EFCS is used at 1/250 with my YS-D3s. So, I would be careful when relying on maximum specs given. The number 9 and 10 footnotes in the screenshot also mention that these speeds are only compatible with Canon’s own flashes.

I usually shoot at 1/200 and use 1 or 2 stop ND filters internally depending on the scenario if I really want to block ambient light. This results in the equivalent exposure of 1/400 and 1/800 of light stopping speed and would also recommend this.

9 hours ago, Thales said:

The x-sync speed of 1/320 applies for cropped resolution which is not very useful:

Are you sure ? It's heavily marketed everywhere!
I still hope that the combination of Electronic Shutter + FullFrame Res will allow you to have X-Sync of 1/320s
That would explain the above exeptions.

Yes, electronic shutter is not supported. It is the same as the R6 II. Above screenshot is directly from Canon.

If you want to use HSS, you should use UW Technics trigger or similar and Marelux’s or Retra’s HSS capable strobes and explore that route.

Anyone get their hands on one to see if it might work in an R6 ii housing? Since Nauticam released a specific housing for it - it makes me think that the III won't fit in the II housing.

I'm happy to report that after some light dremmel work on the mounting tray (seems camera body + screen is 1-2mm thicker than the Mark II, the Canon R6 Mark III fits perfectly in the Nauticam R6 Mark II housing. As far as I can tell, every single button, dial, lever, etc - works the same as on the Mark II.

So while the body does differ a little, the differences seem to be small enough that they're within the tolerences for the Nauticam R6 Mark II housing at least.

Shucks. Now I'm seriously tempted to upgrade....

These guys had to have about 1-2mm sanded off in with a dremmel (I'm sure hand file would work just as well) to let the camera sit properly on the tray since it's marginally thicker. But once I did that.. everything else fit like a glove.

Hi DreiFish, can I ask you if all controls are working fine with your canon R6 III in the R6II housing ? Especially the top left dial for movie/photo switch ? On the official photos its shape and placement looks a bit different between the mark II & mark III.

Thanks !

Edited January 5Jan 5 by Chris Martinat

On 1/5/2026 at 7:02 AM, Chris Martinat said:

Hi DreiFish, can I ask you if all controls are working fine with your canon R6 III in the R6II housing ? Especially the top left dial for movie/photo switch ? On the official photos its shape and placement looks a bit different between the mark II & mark III.

Thanks !

Yes, everything works as far as I could see, including the photo/movie switch. (Sorry, only had the body for a few hours, so didn't test it in the water, but everything seemed to work on land).

Many thanks @DreiFish. Beat me to it :)

Still no one in my community has bought one yet and I might be the first one to purchase it as well.

What I suppose is that if you order only the tray from Nauticam there will not even be a dremel work which is really interesting as they completely designed a new housing for the R6 III.

I also saw that the joystick is a bit more sticking out. How was the joystick usage? Was there any movement not being registered by the camera or was it firmer?

As this also occasionally happens underwater, maybe, it being firmer, will be an accidental benefit.

Here is and interesting YouTube video which overlays a 3d scan of both the Mkii and Mkiii so that you can visualize the size changes. Also, this short shows how the viewfinder top is larger and my interfer with other housings.

Ben