Canon EF to RF adapter question

[bill@plunkettphoto.com]

Please explain how using Canon's EF to RF adaptor with no glass elements doesn't work like an extension tube and prevent infinity focus?

[mcbroomf]

Adapters like these are made to take up the difference in flange focal distances (distance from the sensor to the camera flange) from one design to another.  If you look at the table in the link below you'll see for example that an EF mount flange distance is 44mm while the RF flange distance is 20mm so the adapter is exactly 24mm deep.  If you tried to fit an EF lens onto an RF camera with no adapter then the lens would be 24mm too close to the sensor and you'd get nothing in focus.  Hope this helps.

https://en.wikipedia.org/wiki/Flange_focal_distance