R5/EF Adapter compatibility

[drodow]

Hello, I have the EOS R5 with a Canon Mount EF Adapter and a 70-300mm 5.6L IS USM lens. I need to know it the Canon 1.4x extender will work with this configuration?  I hope so otherwise I will have to sell the 300 and buy the 100-400.
Thank you for your help.

[Tronhard]

I would be surprised if unit variation would account for what I found to be a significant inability to connect my 1.4 unit to the back of the 70-300L.  I could not get it to lock at all.  Using things like gaffer tape sounds to me like a very dubious way to proceed.  If one is going to invest in a lens of the quality of an L lens, it seems to me to be much safer to simply crop afterwards, or put the R5 into crop mode and it will render around 18MP with an image crop of 1.6 and no risk.

As to Canon's compatibility chart; HERE  is a link to what appears to be the current list. 

I have downloaded the official Canon 1.4 and 2.0 MkIII Extender user material which includes their list of compatible lenses HERE and the 70-300 is definitely NOT on the list.  So, if by some means  you can attach the extender, it is not recommended and, IMHO, highly risky.
The EF 70-300L does not appear on the chart.

[FloridaDrafter]

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@Tronhard wrote:

John,  I have the EF 70-300L  lens and both of the Canon MkIII extenders and literally just tried to attach them to the EF70-300L.  According to my experience in doing so, the rear element of the 70-300L has very little travel and the 1.4x MkIII extender cannot be attached at any focal length, while the 2.0x MkIII extender does but only very close to the 300mm FL, so your answer appears to be only partly correct. Furthermore, being a 2x unit, the lens loses 2 f-stops, rendering an effective f-stop of f/11. 
However, I would not suggest using an extender at all as the very limited benefit of attaching an extender is arguably not worth the risk of damage to the rear element is IMHO.  Canon have not recommended using any extenders with this unit.
If there is a 3rd party extender that does work, and you are basing your recommendation on this, it might be helpful to be specific.

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Trevor, after reading Johns post, I tried the EF 1.4X III on my EF 70-300mm L II and it fit after extending the barrel to 300mm. Just from observation, the rear element seems to move quite a bit on the 70-300 L II. Not sure I would use it like this, but on mine it fit and didn't feel forced nor did I feel or hear any disturbing noises when zooming what small amount is allowed with the extender attached.

Newton

[Tronhard]

From what I can see Canon does not make an EF 70-300L MkII lens, they DO make the EF 70-300 IS USM MkII lens, while the OP referred to the L version.  What colour is the lens  you tried?

I have tried to fit the 1.4x MkIII Canon extender to the following lenses, just now:

EF 70-300 IS USM MkI   the extender is too wide diameter to fit
EF 70-300 IS USM MkII  The rear element is fixed and flush, and does not fit
EF 70-300 IS USM L       Fits only the 2.0MkIII extender at 300mm
I cannot find any reference to a 70-300L MkII lens in any Canon lens lists.  The only other lens in this range is the EF 70–300mm f/4.5–5.6 DO IS USM, which I do not have, but is a very rare beast.

[FloridaDrafter]

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@Tronhard wrote:

From what I can see Canon does not make an EF 70-300L MkII lens, they DO make the EF 70-300 IS USM MkII lens, while the OP referred to the L version.  What colour is the lens  you tried?

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Ooops, you are correct, as usual. I was remembering back to the non L push/pull and it's replacement "mark II" and was thinking it was a push/pull L... My bad.

But, yes, I tested the 1.4X III on the 70-300 L.

Newton

[drodow]

Thank you very much for the helpful comments and recommendation!

[drodow]

Thank you for the help and especially the pics showing cropping advantage.  Very helpful info!

[Tronhard]

So, we have many points at which one can be confused!
Certainly, my experience indicates that the EF 70-300L does not accept an extender and I cannot find a listing of any suggestion from Canon that this is the case.  Nor can I find any reference to any lenses apart from the four units I listed.
I agree it seems logical to me that adding the extender between the EF-RF adapter and the body is unlikely to be incompatible.

[Tronhard]

So, just this is what I understand so far...
You and John seem to be able to get the 70-300L to be able to attach the EF 1.4x MkIII extender.
I have now repeated my experiment with that combination three times and under no circumstances does the 1.4x attach to the back - it's not even close...  I can get the 2.0x MkIII unit to attach in much the way John suggests.
HERE I cannot find any current documentation from Canon that they recommend using any extender with the EF70-300L.  THIS is the user guide with the official Canon compatibility list for both of the MkIII extender versions, and the 70-300L is not on the list.

I would certainly be interested to see a specific reference somewhere that they DO.  Otherwise anything else, even if they are work-arounds is a risk of damaging the lens IMHO.

[FloridaDrafter]

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@Tronhard wrote:

"So, just this is what I understand so far...
You and John seem to be able to get the 70-300L to be able to attach the EF 1.4x MkIII extender.
I have now repeated my experiment with that combination three times and under no circumstances does the 1.4x attach to the back - it's not even close...  I can get the 2.0x MkIII unit to attach in much the way John suggests.
HERE I cannot find any current documentation from Canon that they recommend using any extender with the EF70-300L.  THIS is the user guide with the official Canon compatibility list for both of the MkIII extender versions, and the 70-300L is not on the list.

I would certainly be interested to see a specific reference somewhere that they DO.  Otherwise anything else, even if they are work-arounds is a risk of damaging the lens IMHO."

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I think John just stated that it was supposed to attach/work if you extended the barrel to 300mm and that it was limited to 270mm-300mm. I'm not sure where he got that info and I don't think he said he actually tried it. I will go back and reread and make corrections to this post if I'm wrong. At any rate, his statement made me want to examine it further, which I did. I'm silly like that 🙂

EDIT: I now see where john got his info and that he did try it.

I guess you could damage the lens or extender if you forgot you were limited to 270-300mm and tried to pull it back to aggressively to 70mm, but my thought is you are taking a zoom lens, which in my case is why I have the lens to begin with (it's a zoom), and basically turning it into a prime (of sorts) without the advantages of a prime. So, IMO, it's a waste. But from my experiments, the EF 70-300mm f/4-5.6L IS USM with the EF 1.4X III Extender works as a 420mm.

Now, I have no idea why you can't get it to attach and I can't, without a doubt, prove that it does on my end because the EXIF data in DPP 4 from the test shots I took shows just the EF 70-300 L with no mention of the EF 1.4 III extender, and just shows the focal length being 300mm instead of 420mm. Typically the EF 1.4X III shows up in the EXIF data.

This is the EF 70-300mmL, EF 1.4X III Extender, attached to the EOS R5 using the Canon EF-RF adapter.

Screen cap of shot in DPP 4. Image was taken with a 5D mark IV, EF 70-300mmL, using the EF 1.4X III extender at 420mm even though EXIF says 300mm. This is 1 of 2 just to show that it is actually zooming to 420mm.

Screen cap of shot in DPP 4. Image was taken with a 5D mark IV, EF 70-300mmL, without the EF 1.4X III extender from the same spot in the room just to show that the lens is reaching 420mm. This is 2 of 2.

Please note that I used screen captures because the new forum does not show EXIF data any more in my plugin, or I just haven't figured it out yet. What a shame.

Newton

[Tronhard]

Hi Newton:

Thank you for your studied and well-documented answer.  I have been more concerned about two things:

1. the complications of all the variations in 70-300 lenses (there are 4), plus the different versions of the extenders (2x types, 3 versions of each).

2. The (to me) clear statement by Canon that the 70-300L is not on their list of approved lenses compatible with extenders.  So, while I am glad that putting the extender on the lens may work for you (again, it doesn't for me), I am very dubious about the risk of doing so.  For example, the 70-300L extends to zoom in, so if it was accidentally bumped from the front end, it could retract and cause the extender to impact the rear element of the lens.
I challenge anyone to provide proof that this is accepted by Canon in their own documentation - I have already offered links to the contrary. 

So, as I see it the risk is very much the individual's decision. Certainly, in the context of the original question, I think it would be very unwise to suggest an undocumented and unapproved means of adding an extender to a person seeking advice.  I accept the fact that John sought to provide some context, but I am dubious of the validity of the sources he quotes to justify the measure - to me what the manufacturer recommends should be the bottom line.