In my experience, just get the basic Canon Mount Adapter EF-EOS R. The control ring is cool but def not worth the extra cash if ur on a budget. AF speed stays identical since its just a pass-through with no glass inside. Honestly, grab the Viltrox EF-EOS R Mount Adapter for like $55—it's been solid for me for years and saves u a ton of cash tho. gl!

In my experience, moving to the R6 is a game changer, but I'm always a bit cautious about the adapter choice. I've tried many over the years, and honestly, the AF speed is basically identical on all of them because it's a straight electronic passthrough. No glass involved, so ur 70-200mm will be just as snappy as it was on a DSLR. If ur trying to save cash, I've seen people use the Meike MK-EFTR-A Auto Focus Mount Adapter with good results. It's way cheaper than the official Canon versions mentioned earlier. But, from a professional standpoint, I'm always a bit wary of the build quality. Sometimes those third-party ones have a tiny bit of 'play' or wobble, which is sketch for weather sealing on a heavy lens like yours. The control ring on the Canon Control Ring Mount Adapter EF-EOS R is cool, but I personally found it redundant with the R6's existing dials. If ur used to the lens barrel, you probably won't even use it. Stick to a solid metal option for reliability. Cheers!

sooo, I've been shooting Canon for over 15 years and honestly, the control ring is nice but kinda overrated for most people. if ur coming from EF glass, ur probably used to reaching for the lens barrels anyway. in my experience, the real upgrade isn't the ring - it's the drop-in filter version. Here's what I recommend after trying basically every combo out there: * AF speed: It's identical on almost all of them because it's just pins passing data - no glass to slow things down.
* Better utility: Look at the Meike MK-EFTR-C Drop-in Filter Mount Adapter. Being able to slide a variable ND behind your Canon EF 70-200mm f/2.8L IS III USM is a total game changer for video.
* Budget option: The Commlite CM-EF-EOS R works fine, but I've found the weather sealing on the official Canon ones is better for long-term use. Basically, unless u really want that extra dial for ISO, save the cash or get the drop-in. peace.

I am absolutely obsessed with the Metabones Canon EF to RF Mount T Smart Adapter for my heavy glass! While the basic Canon ones are fine, the Metabones build quality is just amazing and feels way more professional for long-term use. If you want a really snug connection that wont wiggle with a heavy 70-200mm, this is definitely the one to get. Quick tip: definitely check out the Fotodiox Pro Fusion Adapter EF to RF as well. It is a fantastic alternative if you want something sturdy and professional without paying the first-party markup. Honestly, the internal flocking on these high-end third-party brands makes a huge difference in contrast when youre shooting in harsh lighting. You really cant go wrong with either of these for your R6!

Facts.