Tbh that point about the communication speed is spot on - it really makes or breaks the eye-AF performance when youre shooting portraits. I went down a total rabbit hole reading community benchmarks and user feedback before I finally committed to native glass. The main thing I noticed from the owner groups is the integration:
- No need for separate USB docks for lens firmware updates
- Perfect compatibility with the R6’s internal correction profiles Honestly, after seeing so many people on the forums mention "glitches" with non-native setups, the peace of mind is worth it, right?

I’ve been diving into the technical specs lately since getting my R6, and one thing I noticed is how much the pin connection matters for compatibility. I tried using a friend's older lens with a basic adapter and the autofocus felt kinda "stuttery" compared to native glass. From what I’ve been reading, the 12-pin connection on Canon RF mount lenses allows for way faster data communication than the old EF 8-pin setup. I think that’s why the eye-detect AF is so much stickier on native glass? Not 100% sure, but it’s something I’ve been researching before I drop my own cash. Quick tips:
1. If you go with an adapter, spend the extra bit for the Canon Control Ring Mount Adapter EF-EOS R. Having that extra dial for ISO is a total lifesaver when you're focusing on a model.
2. Always check if the lens firmware is up to date. I’ve heard some third-party glass can actually fight against the R6’s IBIS (in-body stabilization) if the software isn't current, which basically ruins the sharpness you’re paying for.

Noted!

Bump - same question here

RF 85mm f/2. It works. Cheaper than the 1.2, still sharp enough for me.

Sharpness, eh? Don't sleep on adapted EF glass! A used Sigma 85mm f/1.4 ART with an adapter could be surprisingly good. Technically, the RF primes are newer, but that Sigma is a beast optically. It depends if you *need* native RF. Are you cropping a lot? That's where RF might win.

Honestly, don't overspend. The RF 50mm f/1.8 is surprisingly sharp for the price. Spend the rest on lighting; it'll make a bigger difference than a pricier lens, unfortunately.

Skip pricey RF glass, adapt an EF 85mm f/1.8 USM. Under $300 used. Requires adapter, but plenty sharp. DIY calibration via R6's focus micro-adjustment (check online guides!). Results depend on your adapter quality and patience, but decent option to save serious cash.

Hey! I'm newer to RF lenses, but looking around, it seems like Sigma's consistently getting rave reviews *and* undercutting Canon on price. Are folks seeing that in real life? Happy with my old EF Sigmas (no complaints after 5 years!), and maybe that rep holds true here. Worth a look!

Sharpness is key, but consider the added weight. A heavier lens can shift your center of gravity while driving, especially during spirited runs to scenic overlooks. Think about mounting security first. The RF 85mm f/2 IS STM is a decent option; lighter and less likely to become a projectile in a sudden stop. Prioritize a secure camera mount inside the car. Test it!

Been shooting the RF 85mm f/2 for three years now on my R6. Stopped down to f/2.8, it's plenty sharp for portraits. Honestly, it's a solid performer and the IS has saved me more than once. No complaints after all this time, still happy with it. Reliable workhorse.