EF extender on RF mount?

I'm not really into telephoto shooting much (yet?) but I was just wondering something. So I have an RP and 60D with mostly EF (or EF-S) glasses from the 60D days, and a third party EF lens to RF mount adaptor. One tele lens I have is the EF 70-200 f4L IS. This is quite wild,

1. would an RF extender put on the RP, then the adaptor in front of it, and then the lens work? Or

2. is it better to use an EF extender between the adaptor and the lens then put the adaptor on to the body? Heck,

3. would the second configuration work with an RF extender between the body and adaptor?

I know it would be like f/16 at the brightest aperture (using both 2x extenders) but it's a theoretical experiment anyway. Danke

The only configuration that will work is camera>adapter>ef extender>Ef lens

BobKnDP wrote:

Steven Blackwood wrote:

The only configuration that will work is camera>adapter>ef extender>Ef lens

I'm not disagreeing, but could you explain?

The RF extender expects an RF mount device at the back and and RF mount device up front

The EF extender expects an EF mount device at the back and an EF mount device up front

An RF camera expects an RF mount device up front

An RF-EF adapter expects an RF mount device at the back and an EF mount device up front.

You cannot mount an RF adapter in front of an RF extender, although if you want to hack up your adapter, you can try

https://www.the-digital-picture.com/News/News-Post.aspx?News=35054

If you put this all together

Camera > Adapter > EF Extender > EF lens

BobKnDP wrote:

Steven Blackwood wrote:

The only configuration that will work is camera>adapter>ef extender>Ef lens

I'm not disagreeing, but could you explain?

The short answer is that the RF-EF adapter doesn't physically fit in front of RF extender. The adapter has a protruding baffle inside which interferes with the protruding front element if the extender

So, taking the RF extender out of equation, what remains is above combination

sushipep wrote:

BobKnDP wrote:

Steven Blackwood wrote:

The only configuration that will work is camera>adapter>ef extender>Ef lens

I'm not disagreeing, but could you explain?

The RF extender expects an RF mount device at the back and and RF mount device up front

The EF extender expects an EF mount device at the back and an EF mount device up front

An RF camera expects an RF mount device up front

An RF-EF adapter expects an RF mount device at the back and an EF mount device up front.

You cannot mount an RF adapter in front of an RF extender, although if you want to hack up your adapter, you can try

https://www.the-digital-picture.com/News/News-Post.aspx?News=35054

If you put this all together

Camera > Adapter > EF Extender > EF lens

The CommLite CM-EF-EOS R works better with only minor mods:

Re: How did you stack the EF 2x III and EF 1.4x III: Canon EOS R Talk Forum: Digital Photography Review (dpreview.com)

BobKnDP wrote:

Steven Blackwood wrote:

The only configuration that will work is camera>adapter>ef extender>Ef lens

I'm not disagreeing, but could you explain?

You can put the RF extender behind a suitable, modified EF/RF adapter, and it will function. The only problem is that the R5 will display the RF extender in the EXIF, but it won't multiply the focal length by the extender ratio. So this may affect IBIS stabilization.