TC on an R6

I have an EF70-300L. They are not supposed to work with a TC, but it seems to me that the lens and TC might work on an R6. Here's the question: Should the TC be an EF model or an R version? Would it matter? Would the addition of the EF to R converter foul up the optics in the TC?

Canon EOS R5 -> EOS R-EF Adapter -> EF 1.4X extender-> EF Lens (e.g. 100-400mm F5.6L Mk II) works.

Don't know why it wouldn't work on an R6.

The EF teleconvertor is designed with the assumptioni that the rear optic is mounted so that it is at the proper distance to focus on the film/sensor 47mm from the flange. The RF optic is designed for working with only 20mm flange distance.
The RF lens adator fills in the gap in distance between the RF flange and the EF lens.

If you tried to use the EF teleconvertor, you would have to use this stack:

RF-to-EF lens adapter --> EF teleconvertor --> EF zoom

I don't know that this would even work optically:

RF convertor --> EF-to-EF lens adapter --> EF zoom

dangermoney wrote in post #19235620
Canon EOS R5 -> EOS R-EF Adapter -> EF 1.4X extender-> EF Lens (e.g. 100-400mm F5.6L Mk II) works.

Don't know why it wouldn't work on an R6.

The reason is that you cannot fit the Canon EF TC to the 70-300L.

So the EF TC cannot be attached to the 70-300L. It is a physical limitation. There are many Canon lenses that share this limitation.
The 70-300 is a bit of an oddball being the only white lens (that I know of, I don't know about the white super zooms)

Some 3rd party TC will fit, eg some model Kenkos that do not have protruding element.

It is possible to use an RF TC on the R6, then an adapter, then the 70-300L. You will need to 'hack' the adapter or TC though.
The RF TC's protruding element will not fit inside the Canon Mount Adapter EF-EOS R. So the hack involves, for example, taking a dremel to the adapter.
People who want to do this usually buy a cheaper 3rd party adapter.
The other thing that may work is removing the rubber around the protruding front of the TC. This works for other brand TCs / other brand equipment.

If you do modify an adapter, there is no problem using the RF TC with regards to distances.
RF TC on the camera, or EF TC on the lens (if using say a 100-400 II that the EF TC is compatible with) will work.

The distances are not a problem.

Wilt wrote in post #19235629
The EF teleconvertor is designed with the assumptioni that the rear optic is mounted so that it is at the proper distance to focus on the film/sensor 47mm from the flange. The RF optic is designed for working with only 20mm flange distance.
The RF lens adator fills in the gap in distance between the RF flange and the EF lens.

If you tried to use the EF teleconvertor, you would have to use this stack:

RF-to-EF lens adapter --> EF teleconvertor --> EF zoom

I don't know that this would even work optically:

RF convertor --> EF-to-EF lens adapter --> EF zoom

It will work (optically)

https://www.the-digital-picture.com …News-Post.aspx?News=35054
Hacked: Making All Canon EF and EF-S Lenses Compatible with Canon RF Extenders

As Bryan kindly provided me with hindsight, I can sound smart by explaining why it works

Things we already know:
A TC provides an 'extension tube compensation factor' or whatever term you prefer.
An EF, TC compatible, lens is designed for a specific flange distance.
Using an extension tube changes the lens characteristics in a predictable way. Working distance is reduced, maximum magnification increases as a result, ability to focus at infinity is lost.
If we fit a TC however, working distance does not change, maximum magnification is increased due to the increase in focal length, ability to focus at infinity is retained.

The fact infinity focus is not lost provides the 'extension tube compensation factor'.
Maybe it is more accurate to say the plane of focus is moved forward by the TC. With the protruding element, I don't know if it moved to the front mount surface of the TC or the front of the protruding element. Whichever, fitting the RF 1.4 TC to the R6 means that it is now configured to accept an RF lens, or an EF lens with an EF-R adapter. Either the EF or RF choice will result in 1 stop of light loss and 1.4X increase in maximum magnification, but flange distance will be correct for either choice.

Thx for that explanation, Choderboy!

Time for me to play with an extension tube placed between EF teleconvertor and EF lens, to see what happens!

edit after test:
Canon 5D, Kenko 1.4x teleconvertor, aftermarket 21mm extension tube, Canon70-200mm f/4 IS lens

• at 70mm lens setting, combination focuses extremely close, to about 1.6' (compared to standard 4' MFD)
  
• at 200mm lens setting, combination focuses to about 3' ' (compared to standard 4' MFD)
  
• at 70mm lens setting, camera could not focus at 7'
  
• at 200mm lens setting, camera could focus at 7'
  
• Infinity focus lost at any FL
  

Although our Moon is only 240,000 miles away at not at infinity, this combination had no problems focusing on our Moon.

The images of Saturn and Jupiter were added in, using the same set up.

Cheers

Dennis

nardes wrote in post #19235973
Although our Moon is only 240,000 miles away at not at infinity, this combination had no problems focusing on our Moon.

The images of Saturn and Jupiter were added in, using the same set up.

No... you could not have gotten two planets in close conjunction with the moon, without Photoshop! or was this 'once in a blue moon'?

Canon 100-400mm Lens + Canon 1.4x TC + Canon extension + Canon 2xTC + Canon 2x TC + Canon RF-to-EF adapter, is that what I see?
Were you able to maintain communications to the lens from body, even with this stack?

Wilt wrote in post #19235976
No... you could not have gotten two planets in close conjunction with the moon, without Photoshop! or was this 'once in a blue moon'?

And probably not in the same exposure, either

Wilt wrote in post #19235976
No... you could not have gotten two planets in close conjunction with the moon, without Photoshop! or was this 'once in a blue moon'?

Canon 100-400mm Lens + Canon 1.4x TC + Canon extension + Canon 2xTC + Canon 2x TC + Canon RF-to-EF adapter, is that what I see?
Were you able to maintain communications to the lens from body, even with this stack?

"The images of Saturn and Jupiter were added in, using the same set up."

Did you miss this in the original post, indicating that Jupiter and Saturn were added in, i.e. not part of the Moon shot, but added in in post?

Cheers

Dennis

nardes wrote in post #19236056
"The images of Saturn and Jupiter were added in, using the same set up."

Did you miss this in the original post, indicating that Jupiter and Saturn were added in, i.e. not part of the Moon shot, but added in in post?

Cheers

Dennis

was making levity!

Wilt wrote in post #19236061
was making levity!

Ahh, got it now - thanks.

Just in case more details are required on how this combo works, here are links to previous post:

Jupiter and Saturn images.
https://photography-on-the.net …showthread.php?​p=19133296

Moon image.
https://photography-on-the.net …showthread.php?​p=19133339

Cheers

Dennis

Nardes, I am no astrophotographer, so I have no inherent understanding.

Is the blur of the two planets caused by Earth atmostpheric induced blurring, or
is the blur due to the planets moving too fast for the shutter speed selected for gathering of dim light?

Wilt wrote in post #19236111
Nardes, I am no astrophotographer, so I have no inherent understanding.

Is the blur of the two planets caused by Earth atmostpheric induced blurring, or
is the blur due to the planets moving too fast for the shutter speed selected for gathering of dim light?

#1 - atmospherics.

However, with a (large) telescope and a decent webcam, you can record movies files comprising several thousand frames of the Moon and Planets, and then process the movie file in specialised astro SW, which analyses each of the frames (typically 4,000 upwards) for quality, so you can then select say, the best 10% to then Align and Stack them to improve the image quality and minimise unwanted noise.

This is called "lucky imaging" as the SW is selecting the best frames and rejecting those where the atmospherics have smeared the surface detail.

Cheers

Dennis