I have a EF 70-200 F/2.8 IS lens and a canon 5D Mark IV. I'm planning to upgrade to an R6. I will sell the 5D.

I will purchase the EF to RF adapter so that I can use the 70-200 mm lens and other EF lenses that I own on the R6.

All that's good, but I will be going to safari in Kenya in a few months and to extend the reach of the lens I'll need a 2X Extender.

I know the Canon EF 2X Extender is compatible with the EF 70-200. However I'm not sure if the setup outlined below even works.

Note: "" means "mounted on"

EF 70-200 → EF 2X → EF to RF adapter → R6 camera

On paper this works, but will I face auto focus issues? I know I'll lose 2 stops of speed and some image quality. I can't afford the 100-400 mm glass (either the RF or EF versions). Anyone else tried this set-up and had any issues?

I guess I could hold off on selling the 5D until after the Kenya trip and use the 5D with the 2X Extender on the 70-200. The R6 could be the backup camera with a 24-105 f4 lens for landscapes and for shots of animals that get too close for the extended 70-200.

But ideally I want to sell the 5D before going to Kenya as it will defray the cost of the trip.

PS: wish I was rich 🤑

  • \$\begingroup\$ The EF to M adapter is basically an extension tube that carries the electrical signals to the EF lens. There are off brand versions that are much less expensive than the Canon one. The switch to the M6 will reduce the sensor size to APS-C, effectively lengthening your focal lengths by a factor 1.6. That will be a good thing here. I have used the Canon 1.4x extender and EF-M adapter with the 100-400 and 35/1.4 with good results. \$\endgroup\$ Commented Mar 6, 2022 at 16:24
  • \$\begingroup\$ If the off-brand versions are like some off-brand extension rings I know, they will have some slack and I wonder what that does to the lens alignment... \$\endgroup\$
    – xenoid
    Commented Mar 6, 2022 at 20:59

1 Answer 1


There's nothing in your setup that shouldn't work. In general, if a setup consisting only of official Canon components works on an EF mount camera, it will work on an RF mount camera with the adapter.

Since this setup works:

EF 70-200 --> EF 2x TC --> 5D camera

This will work too:

EF 70-200 --> EF 2x TC --> EF to RF adapter --> R6 camera

With non-Canon lenses it might be different. For example, I understand that Tamron teleconverters may not work at all on RF cameras and that many Tamron lenses require firmware update to work, and even then, they will have autofocus issues. Some older Tamron lenses may not even have a firmware update available.

Do note that autofocus will be slower with a teleconverter. Likely it will be usable, though.

If you haven't purchased the teleconverter and EF to RF adapter yet, something else to consider: RF 100-400 f/5.6-8. Not much more expensive as new than a 2x converter plus the EF to RF adapter together. Your 70-200 is a f/5.6 lens with a 2x teleconverter. The RF 100-400 f/5.6-8 is one stop slower than f/5.6 in the tele end. It may also be sharper.

I don't think losing the one stop of light is fatal in this case. People are doing bird photography on Canon f/11 lenses in daylight. Compared to that, f/8 is fast.

f/8 will not gather enough light at sunrise and sunset, though, but then again, f/5.6 will not do that either.

  • \$\begingroup\$ Juhist, thanks for your response. Excellent suggestion on the RF 100-400 mm f/5.6-8 lens. However I have a few other canon EF lenses and either I get rid of all of them and buy their RF equivalents (expensive undertaking) or choose the more cost effective option of buying the EF to RF adapter. The EF to RF adapter is basically a necessity. Once that's bought I think the EF 2x TC makes sense. In a year or two I could save up for a 100-400 mm L series lens rather than buying the slower but cheaper RF 100-400 non-L lens. Photography is all about tradeoffs! \$\endgroup\$
    – Vikram B
    Commented Mar 6, 2022 at 12:10
  • \$\begingroup\$ Keep in mind that the R6 is not AF limited by apertures narrower than f/5.6 the way the 5D Mark IV is. That's one of the advantages of Canon's newer mirrorless bodies. Also keep in mind that using an EF 2X extender with your 70-200mm f/2.8 IS and 5D Mark IV will cause focusing to be slower. If you use the EF 2X III, image quality doesn't take near the hit it did with the older EF 2X and EF 2X II extenders. Having said that, I wouldn't personally use any 2X with the original EF 70-200mm f/2.8 L IS, only with the EF 70-200mm f/2.8 L IS II or III versions. There's that much difference at 200mm. \$\endgroup\$
    – Michael C
    Commented Mar 15, 2022 at 8:26
  • \$\begingroup\$ Having said all of that, if it were me I'd rather spend the cost of an EF 2X on renting an EF 100-400mm IS II (it's a much better lens than the original) instead. Or rent a 7D Mark II (the 20 MP APS-C sensor has the same pixel density as a 50MP FF sensor) to use with the 70-200 and crop the stink out of it. The only time I've found a 2X makes sense with a 70-200 II is with tripod mounted astro work. For sports/action when I know I'll need to crop at least as tight as an APS-C sensor, I find that using my 7D Mark II with higher pixel density works better than using my 5D Mark IV. \$\endgroup\$
    – Michael C
    Commented Mar 15, 2022 at 8:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.