EOS R EF Lens Compatibility

[Nitro54]

I have a question I hope someone can answer for me.

I have the Canon R camera. I found a good deal on a used EF 600 older lens.

Can I put on my R to EF lenses converter, put on a 2x teleconverter, then the lens

and still have it work on my camera? 

Thank you, Glen

[kvbarkley]

I doubt the teleconverter will yield good image quality, but it should work. Ken Rockwell showed something like this.

[kvbarkley]

Found it!

https://www.kenrockwell.com/canon/eos-r/r.htm

Scroll down the page to see him use the EF 100-400, a 1.4 TC and a 2.0 TC!

[Nitro54]

I have the RF 2x and a RF 100-400 lens. Just looking for more reach with a full frame camera.

[Mitch_P]

It will work, but the picture quality won't be as good as with the RF Extender. There's a hack out there to modify a cheap EF to RF adapter and use the RF Extender on an EF lens. I tried it and it works, but it's definitely not ideal.

[Waddizzle]

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@Mitch_P wrote:

It will work, but the picture quality won't be as good as with the RF Extender. There's a hack out there to modify a cheap EF to RF adapter and use the RF Extender on an EF lens. I tried it and it works, but it's definitely not ideal.

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I’m not so sure about that.  He wants to use the RF Extender with the RF-EF mount adapter.  I do not believe that would work.  The RF Extender is made exclusively for RF lenses, not adapted EF lenses.  The OP needs an EF Teleconverter for EF mount lenses.

It might though.  One can never say never.  I would be truly surprised if it did.  

[Mitch_P]

I read it as camera -> to EF-RF converter -> to EF Extender -> then EF Lens. That definitely works, I've done it many times. The RF Extender -> to EF lens is do-able with a hack. It will also work with lenses that are not normally compatible with a extender. The EXIF gets a little messed up, but lists the RF Extender so it's not unworkable. Not ideal, but it's just a hack. And the RF extender is a lot sharper than the EF II, at least to my eye. I haven't tried the EF Extender III.

[ata]

Of course it works, I have Canon Ef 300mm f/2.8L IS USM II + 2x Extender III +1.4x Extender III with RF-EF mount adapter but I recommend you buy a 1.4x III converter instead of 2x III. You can get cleaner photos than 2x III.

[Nitro54]

I just tried a RF 2x extender and, RF-EF adapter and a EF 75-300 lens

and the Rx Extender won't attach with the adapter. Looks like I would also need a 

2x Extender III  or 1.4x Extender III  to make this work. Thanks for all the advice.

[Mitch_P]

Your description is confusing. An RF Extender will not work with an EF camera or lens, or stock EF-RF adapter.