Canon Explorer of Light Keith Ladzinski and the RF600mm F4 L IS USM Lens 

Congrats bloke, you must be wealthy.

He was.....and then he bought an rf 600 f4 !!!

Hi Noa! Interesting question. You will need a Mount Adapter EF-EOS R to use any EF series lens with the R5. The mount adapter will not affect the performance of the EF lens. Now if you also want to use an Extender EF 1.4x, this will reduce the light reaching the sensor by 1 f-stop. This can affect the performance some compared to the EF lens without the Extender. Our camera support agents can explain this in more detail. You can reach them at 1-800-652-2666 Monday-Friday: 9:00 am to 9:00 pm ET, Saturday: 9:00 am to 7:00 pm ET, excluding holidays. Hope this helps.

@@CanonUSA Excellent! I'll contact them tomorrow!

Hi Jeffery! Using the R5 with a battery grip does not change the focusing speed of the lens. We hope that helps.

@@CanonUSA Thanks much for your input! Kind regards

Hi Peter, This lens is optically identical to the EF 600mm f/4L IS III USM lens and no difference in focusing speed is listed. The EF version requires an adapter to mount to R-series cameras. If you have additional questions, our camera support agents are happy to help. You can contact them via 1-800-652-2666 Monday-Friday: 9:00 am to 9:00 pm ET, Saturday: 9:00 am to 7:00 pm ET, excluding holidays. We hope this helps.

@@CanonUSA Thank you very much for the quick reply. It was just a matter of technical interest. It is said in the advertisement that with the R3 the new RF optics would focus faster. I recently own the RF600/F4. I didn’t find any practical difference in focusing speed between R3 and R5 nor to an adapted EF400/F2.8. Thank you again.

No worries! We take arms and legs as well!

It might be a lot easier to own the RF600mm F4 L IS USM by taking advantage of interest-free financing from PayPal. Visit canon.us/3RTSS7f to learn more!

While Keith would know for certain, he earlier references the Mara River that runs through Kenya and Tanzania. That might a good starting point!

Southern carmine bee-eater

What canon camera body did u use for this lens?