7D, Extender, Autofocus ?

[cheech]

Hi All,
I've been searching but cant find my answer.
I have a 7D and a 100 - 400L.
If I use an extender will I loose autofocus ?

Anybody tried this set up with the mk111 extender ?

Would like to go 2x but what would be the minimum f stop ?

Thanks in advance for any advise.

 

[AndrewA]

Simple answeris yes you will. However some have managed AF using non reporting extenders duch as the Kenko 300 DGX or by taping the pins on a canon 1.4. Ive tried without success on a canon 1.4 TC. AT BEST AF WILL be slow and quite hit and miss i suspect and youll need very good light.
Using a 2x will give F11 so my guess AF will be impossible.
Andrew

http://www.andrewa.zenfolio.com

 

[modchild]

I still got my 100-400 to AF with a Kenko Pro300 DGX 1.4x extender on a 7D, a 550D and a 5D2. It worked really well, the AF speed wasn't slowed down by much and it focussed in most light, only started hunting in poor light, and the IQ didn't seem to be affected much either. So although Canon cameras, apart from the 1D, will AF up to f5.6 it does seem that if you use the right extender you can get away with it. The Kenko also reports correctly in the EXIF and doesn't need taping if you get the newer DGX model.

With a 2x extender it would make it f11 which would have to be manually focussed. I've just ordered a MkIII extender, but I no longer have a 100-400 to try it on. I've got it for my 70-200 2.8 MkII to make it up to a 140-400 f5.6.