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Occasional Contributor
Posts: 9
Registered: ‎05-17-2018

Canon R5 with Extender


will this setup work?

Canon R5 + 2X teleconverter + Canon 70-300mm f/4-5.6 L IS USM.


of course, R5 would need an RF-EF Adapter. But is this scenario even possible with 4-5.6 Aperture?


Thanks in advance.

Posts: 11,698
Registered: ‎08-13-2015

Re: Canon R5 with Extender

That lens does not even work work on EF mount with extenders

"Doctor told me to get out and walk, so I bought a Canon."
Respected Contributor
Posts: 1,436
Registered: ‎01-25-2018

Re: Canon R5 with Extender

As Wadizzle states, that 70-300 is not compatible with either the 1.4X or 2X converters because of the lens construction which won't allow mounting it.


The IQ of that particular lens isn't great to start with and even Canon's best great white primes produce significantly reduced image quality when used with a 2X converter.  Crippling one of Canon's better efforts with a lousy lens setup is a really poor approach.  If you are looking for decent image quality, you don't want to choose any lens that requires the use of a 2X to provide the focal length range that you need. 


With the better Canon primes (and the later 70-200 f2.8 effort), the 1.4X produces very nice although still somewhat degraged images but if you are at all critical about image quality, the 2X isn't going to suit you.  I have Canon's 300 and 400 f2.8 great white primes which I believe are as sharp as anything Canon makes.  Images made with either lens and a 1.4X are quite good but the same isn't true when using a 2X.





EOS 1DX M3, 1DX M2, 1DX, 5DS R, 1D M2, EOS 650 (film), many lenses, XF400 video
Frequent Contributor
Posts: 119
Registered: ‎11-14-2018

Re: Canon R5 with Extender

[ Edited ]

If you are looking to use the longer fl on an R5 why not pickup an RF 600mm or 800mm prime.  They are f11 only but still work quite well with the R5.  They are not real inexpensive but quite a bit of bang for the buck.  I have the 600mm and have been very happy with it.

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