> I thought it would be magic, but unfortunately, it felt... Just found this thread today. I went through this last year when I picked up my R6 and had a bag full of older Sigma glass. Honestly, I totally get the hesitation with the official one being so pricey. I ended up trying the Meike MK-EFTR-A Auto Focus Mount Adapter which was only like $50. Basically, it felt pretty solid but I did notice some slight wiggle with my heavier Sigma 70-200mm f/2.8 DG OS HSM Sports for Canon EF. It was super annoying cuz I hate loose mounts. Then I tried the Commlite CM-EF-EOS R Mount Adapter which cost me about $60. Technically, the metal finish on the Commlite felt a bit better and the AF hunting wasnt any worse than the official one my buddy let me borrow. I guess the real trick is checking for firmware updates on the adapter itself, which some people forget. If your on a budget, maybe look at those options but just be careful with the heavier glass because that mount tension is literally everything for long term reliability. idk if it's magic but it saved me enough cash for a new battery lol. gl!

Respectfully, I'd consider another option. Honestly, I had a bit of a disappointing experience with the official Canon Mount Adapter EF-EOS R because it's like $130 and didn't really fix the autofocus hunting on my older glass like I expected. I thought it would be magic, but unfortunately, it felt just like the cheaper ones I tried later. If you're looking to save money for other gear, there are way more budget-friendly ways to go:

• Commlite EF-EOS R Mount Adapter
• Usually around $45 and basically does the same thing.
• Meike MK-EFTR-A Auto-Focus Mount Adapter
• About $50 and it's built surprisingly well.
• Viltrox EF-R2 Mount Adapter
• This one has the control ring for like $80, which is highkey a steal. So yeah, I guess I'd say save ur cash. I mean, the official one is nice but is it $80 nicer?? Probably not if ur just using older lenses that might struggle a bit anyway. good luck!

To add to the point above: the reliability of these things usually comes down to the internal pin contact quality and the protocol translation between the older lens chips and the RF communication speed. I think the issue with older Sigmas specifically is often the firmware on the lens side rather than the adapter itself, which can lead to some weird behavior regardless of the brand you pick. Before I can suggest a specific path, i had a couple questions:

• which sigma models are we talking about specifically?
• are they the older ex series or the newer global vision stuff?
• are you planning to use high speed burst modes often? Not sure but I think I remember reading that some third party adapters might struggle with the power draw of those older big glass elements. Iirc some people mentioned internal reflections on some of the cheaper metal tubes too... honestly i havent seen it myself but its something to watch out for. lmk the lens details and ill see what i can find.

I would suggest sticking with the official Canon adapter for your switch. Yeah, honestly, I've been using EF glass on RF bodies for years and you gotta be careful because some third-party mounts I tried felt kinda loose after heavy use. With those older Sigma lenses, you really dont want to risk AF hunting or communication errors. Its definitely worth the extra cash for that long-term reliability!! gl!