EF and EF-S lenses can be used on the Canon EOS R mirrorless camera by using a Canon EF-EOS R mount adapter. Canon provides 4 different adapters, each offers distinctive features, but all are 24mm deep and allow you to use your existing EF and EF-S lenses on an EOS RF mount. They do not have any lens elements so there is no loss of image quality. The standard adapter only allows EF and EF-S lenses to be used on cameras with an RF mount with full functionality. The other three adapters. The next model is the Control Ring Adapter, which adds an extra control ring. The third adapter is a Drop-in Filter Mount Adapter within a drop-in circular polarizing filter. The fourth is a Drop-in Filter Adapter with a drop-in variable ND filter.