Canon Extender EF 1.4 X III/EF 2X III (on a 70-300mm f/4.0-5.6L)

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Emmet Brickowski
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I'm getting told mixed things when I enquire about the Canon EF 2X Extender III or the 1.4 X III.

Maybe you good people can put things right.

Will the above extenders work with a Canon EF 70-300mm f/4.0-5.6L IS USM?

Some people are saying yes, other no, others yes but only at 300.

Anyone know the real answers?
 
No, they won't work on the EF70-300mm f/4-5.6 L IS USM

The only one that I know that works for certain is the Kenko Pro 300 DGX 1.4x and it works really well too! :)

There's a protrusion on the Canon converters that prevents them from connecting with the lens.

Hope that helps,
Si
 
Spiritflier said:
No, they won't work on the EF70-300mm f/4-5.6 L IS USM

The only one that I know that works for certain is the Kenko Pro 300 DGX 1.4x and it works really well too! :)

There's a protrusion on the Canon converters that prevents them from connecting with the lens.

Hope that helps,
Si
Click to expand...

Helps a lot, thank you. Do you have the Kenko Pro 300 DGX 1.4x yourself?
 
Yeah, I bought it especially for the 70-300L and it worked brilliantly. Image quality was outstanding with it! :)
 
Spiritflier said:
Yeah, I bought it especially for the 70-300L and it worked brilliantly. Image quality was outstanding with it! :)
Click to expand...

Cheers. Just trying to find the best price to get one :)

As above. Does auto focus work well?
 
sigma extensions are also usable also and autofocus is possible just somewhat slower
 
Daverkl said:
Cheers. Just trying to find the best price to get one :)

As above. Does auto focus work well?
Click to expand...

Canon extenders won't fit, Kenko will, Sigma maybe. But none of them will AF because any extender takes the f/number over the f/5.6 ceiling for all Canons except 1D and 1DS.

Don't believe those who say you can tape over the communication pins and fool the camera. That doesn't change the fact the the aperture has been changed optically so, if the AF works at all, it will be poor.
 
HoppyUK said:
...none of them will AF because any extender takes the f/number over the f/5.6 ceiling for all Canons except 1D and 1DS...
Click to expand...

I'm sorry Richard but you're wrong... The EF70-300mm f/4-5.6L IS USM works perfectly well with the Kenko Pro 300 DGX 1.4x teleconverter! :)

If the autofocus didn't work properly, there's no way I'd have got this shot! The proof is in the EXIF.

 
Spiritflier said:
I'm sorry Richard but you're wrong... The EF70-300mm f/4-5.6L IS USM works perfectly well with the Kenko Pro 300 DGX 1.4x teleconverter! :)

If the autofocus didn't work properly, there's no way I'd have got this shot! The proof is in the EXIF.

Click to expand...

Faved :lol:
 
Spiritflier said:
I'm sorry Richard but you're wrong... The EF70-300mm f/4-5.6L IS USM works perfectly well with the Kenko Pro 300 DGX 1.4x teleconverter! :)

If the autofocus didn't work properly, there's no way I'd have got this shot! The proof is in the EXIF.

<snip>
Click to expand...

Clearly I'm wrong there! What camera was that on? My exif reader won't pick it up.

But it shouldn't work, as Canon states, though I have heard a couple of reports of the 5D3 and 1DX actually doing what they're not supposed to. Other cameras though, a very mixed bag. From my own experience, 7D wouldn't, 40D wouldn't, old 350D would AF very slowly with pins taped (100-400L, Kenko 1.4x).
 
Hi Richard,

It was on the 5D3 but it also worked on my 5D2 and my old 7D... I know about the whole 'f8' thing but it even works well on a friends EF100-400mm. I guess it'll have to sit in the file along with my 300mm f/2.8 and TC issue! :)

Cheers,
Si
 
Spiritflier said:
Hi Richard,

It was on the 5D3 but it also worked on my 5D2 and my old 7D... I know about the whole 'f8' thing but it even works well on a friends EF100-400mm. I guess it'll have to sit in the file along with my 300mm f/2.8 and TC issue! :)

Cheers,
Si
Click to expand...

That's all good info Si :) Just to be clear, is the 5D2/3 and 7D all with the 70-300L and Kenko 1.4x?

Cheers.
 
HoppyUK said:
That's all good info Si :) Just to be clear, is the 5D2/3 and 7D all with the 70-300L and Kenko 1.4x?

Cheers.
Click to expand...

Yep, it was all three models... I'll have a dig through my files for some more examples when I get five minutes. Here's one more example from Flickr that pretty much proves the AF accuracy! :)

 
This is my understanding of how things work:
Reporting TCs (Canon I & II, Kenko DG, Sigma): A TC-compatible lens (e.g. 400/5.6) detects the presence of a TC through the 3 extra contacts and reports the correct f-stop for the combination to the camera. If the f-stop is above f/5.6, AF is disabled for non-1-series bodies.

Non-reporting TCs, or taped TCs, or TCs with non-TC-compatible lenses: The lens does not detect the TC and just reports its own f-stop. AF may still work, because the camera doesn't know about the true f-stop, and tries to AF even if the combination is outside the specs.

Kenko DGX: Unlike the above TCs, the DGX manipulates the communication between the lens and the body so that the f-stop is always reported correctly for the combination, and so that AF is retained even if the combination is above f/5.6. From your and others observations that f/8 is reported but AF still works, my guess is that wide-open f-stop and used f-stop is reported separately and the camera looks at the wide-open f-stop to determine if it should try to AF.
 
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