# Extender EF 2X III Help



## westr70 (Dec 4, 2014)

I bought 2 X Mark III extender on ebay to use with a 300mm f2.8 II (which I haven't bought yet) and tried it out on my 5dMarkIII and 7dMarkII with my 70-200mm f2.8 lens. No autofocus at any aperture. I checked the autofocus on the lens and it was on. Did I make a mistake in my assumptions that it would work on these cameras? or is something wrong with the extender. I use my 1.4 extender and it works fine. The 2X extender looks immaculate with everything clean and the sensors bright and shiny. Any ideas would be appreciated.


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## Dylan777 (Dec 4, 2014)

Make sure lens, 2x TC III and body making good contact. Otherwise, you might got a bad one.

My 70-200mm f2.8 IS II & 2x TC III combo works just fine on 5D III.


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## westr70 (Dec 4, 2014)

It's pretty snug Dylan. Once its locked in, it doesn't move. The contacts look clean too.


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## DanoPhoto (Dec 4, 2014)

Return to seller for a refund. If he will not honor the return, hopefully the transaction qualified for buyer protection from eBay.


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## neuroanatomist (Dec 4, 2014)

DanoPhoto said:


> Return to seller for a refund. If he will not honor the return, hopefully the transaction qualified for buyer protection from eBay.



A'yup...it's broked.


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## East Wind Photography (Dec 5, 2014)

westr70 said:


> It's pretty snug Dylan. Once its locked in, it doesn't move. The contacts look clean too.



Return to the seller and buy a used one from B&H or Adorama. They guarantee everything works.


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## Mt Spokane Photography (Dec 5, 2014)

You should have no issue returning it to the seller, but you might have to pay return postage.


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## DanoPhoto (Dec 5, 2014)

East Wind Photography said:


> Return to the seller and buy a used one from B&H or Adorama. They guarantee everything works.




+1


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## dgatwood (Dec 5, 2014)

Does aperture control actually work? If so, autofocus ought to work, because it uses the same communication pins. You might check your camera's AF settings to make sure it is set to continue searching upon a focus miss.

Failing that, the TC might be decentered or something.


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