Patent: Canon RF APS-C pancake prime lens optical formulas | Canon Rumors

Exactly. The M6 with M22mm fits in my coat or cargo pants pocket.

When going to an event where my primary lens was the 70-200/2.8, it was great to be able to drop the EF 40/2.8 into my pocket and swap on a normal focal length lens as needed (I typically carry with a BR strap attached to the lens foot, so the 70-200 could simply dangle from that as I shot with the 40 mm pancake) – it was a great, portable solution.

That’s not really an option with my R3, because having to carry both the adapter and the pancake lens defeats the purpose. I would definitely like a normal or wide (not ultrawide) pancake prime for RF full frame.