EF/EFS compatibility with R5 Markii

[krisz314]

I have read conflicting information on R5 Markii compatibility with EF/EFS lenses. Can they be used with an adapter or not? thank you

[shadowsports]

Greetings,

Most yes.  You may run into some compatibility / performance issues depending on age.

I'd avoid using EF-S lenses with a full frame body because it will reduce your effective resolution.  

[longqin11368]

I use my EF lens on Canon R8 with a converter, never had any issues. Make sure you get a high quality converter. 

[p4pictures]

If you use Canon EF-S lenses on the EOS R5 Mark II, the camera will automatically select 1.6x crop mode, so you only capture 22MP images, not the full 45MP. Some lenses designed for crop sensor DSLRs from other brands do not correctly tell the camera they are crop lenses and then you may see vignetting - significant darkening of the corners of the frame. 

EF lenses can be used, but depending on the age and model of lens you may find some restrictions of the functions or speed of the camera compared to using RF lenses.