EF 70-200mm has no autofocus with EF 2.0x II Extender

[murdocda]

I was gifted 2 Canon extenders 1.4x II and 2.0x II from a close friend who has passed. The 1.4 works great but the Auto Focus on the 2.0 does not work. I have cleaned the contacts which did not work. does anyone have any suggestions? Can it be repaired? Do I just toss it?

I would really like to keep and use this extender, coming from a friend.

Can any offer any suggestions?

Dave

[murdocda]

To all those who are trying to help me with this issue. I understand that the extender itself has no focusing ability and that it merely passes the communications between camera body and lens.

Using Canon EOS Rebel T5 body

Canon EF 70-200 Ultrasonic lens

Dave

[p4pictures]

There are multiple versions of the EF 70-200mm USM lens, and some will not work.

Look closely on your lens and it will include the maximum aperture value as part of the lens name and is written on the lens right at the front. On my lens the text is EF 70-200mm 1:2.8 L IS II USM and this will work on your camera with both the 2x and 1.4x extenders. 

However if the 70-20mm lens you have has the text EF 70-200mm 1:4 L on it, then your lens has a maximum aperture of f/4. With a 1.4x extender this becomes and effective f/5.6 aperture, but 2x extender makes the combination f/8. Your Rebel T5 is one of the cameras that needs the lens and extender combination to be f/5.6 or more, and therefore you cannot use the f/4 lens with the 2x on your camera and get AF to work. 

Check the spec table for the camera here: https://global.canon/en/c-museum/product/dslr818.html

Where you will find the text: 9-point (Cross-type AF sensitive to f/5.6 with center AF point)

These links are to the two latest versions of the 70-200mm lens

f/4 version - https://global.canon/en/c-museum/product/ef467.html 

f/2.8 version - https://global.canon/en/c-museum/product/ef469.html 

There is quite a size and weight difference between f/4 and f/2.8 lenses.

[murdocda]

Brian, First of all, thank you for spending time in helping me. I really appreciate it. My lens doesn't look like either of the two lenses you had links for. I have attached images of my lens.

Thanks,

Dave

[jrhoffman75 · Accepted solution]

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@murdocda wrote:

Brian, First of all, thank you for spending time in helping me. I really appreciate it. My lens doesn't look like either of the two lenses you had links for. I have attached images of my lens.

Thanks,

Dave

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This is the f/4 variant of the 70-200mm zoom. That is why I asked the question that I posted.

As shown in the chart posted by Stephen it has an effective f/stop of f/8 with the 2X extender.

The Rebel T5 cannot autofocus with a lens having an effective f/stop smaller than f/5.6. That is why everything worked well with the 1.4X and no joy with the 2X. You could use Live View to focus. 

[murdocda]

John, thank you very much for the time and effort that you have devoted to my problem. It appears that my camera and lens combination will not permit me to use the 2.0 extender well disappointed, I’m glad that I know why it’s not working; just not that it was broken For the nature shots that I plan to use that extender for the focus would be infinity in most cases anyway. Once again, thank you. Dave.

[Waddizzle]

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@murdocda wrote:

John, thank you very much for the time and effort that you have devoted to my problem. It appears that my camera and lens combination will not permit me to use the 2.0 extender well disappointed, I’m glad that I know why it’s not working; just not that it was broken For the nature shots that I plan to use that extender for the focus would be infinity in most cases anyway. Once again, thank you. Dave.

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That is accurate, but it does not tell the whole story.  It is not as simple as that.  There are far more moving pieces and parts than you seem to realize.

As I pointed out in my first reply, there are multiple actors that go into the how an extender perform.  Extenders only work with telephoto lenses.  The 2x will extender would work with with a 70-200mm f/2.8 lens with your T5, but not with a 70-200mm f/4 lens.  

Please refer to the document at this link, which explains lens groups for the EOS 90D.  This should give some idea how complicated the question of compatibility really is.  Your T5 cannot autofocus with lenses that have a maximum aperture smaller than f/5.6.

https://gdlp01.c-wss.com/gds/8/0300036248/02/eos90d-si2-en.pdf