No 2X extender for 70-300mm L Series

[Mt Spokane Photography]

I've used non reporting extenders on many different lenses and bodies. There is no pattern that I can find to determine what will work with any given body. There is enough variation body to body apparently, that some bodies work, and another body of the same model won't.

My old 40D was one of the best I've seen for focusing at f/8 or even f/11. My 1D MK III would sometimes focus at f/11, but very slow, but manually pre-focus to the approximate area and it would snap in instantly.

You just have to try, but don't overlook manually focusing first, and then seeing if AF will lock on.

My 70-200mm f/4L IS seemed to be pretty good focusing on some bodies at f/8 or even f/11. I could stack a 1.4 and 2X on it and often it will focus fine.

I'm interested in seeing how the 5D MK III does with its -2 EV low light AF capability.

 

[brianwallace21]

If you buy the newest models (DGX) you do not need to tape pins. The aperture and focal length will still report correctly but the Kenko does not cause the AF to be deactivated.

@wallybarthman: Are you using a 1d body which does af @f8? Because what you're saying is the opposite of everything else I ever read of putting a 1.4x tc on a 5.6 lens and using it on a non-1d eos body!
[/quote]

I am not - this is on a 7D.

Kenko changed how the TCs report when they moved from the DG to the DGX series. The DG series (and I owned a 2x DG model) would disable autofocus if it went above f5.6. However, the new DGX series TCs do not disable autofocus. In fact, I can stack teleconverters (Canon 2x, Kenko 2x, Kenko 1.4x) on my 200 f2.8 and it reports the correct aperture (f16 in this case) and still does not disable autofocus.

 

[Marsu42]

Kenko changed how the TCs report when they moved from the DG to the DGX series. The DG series (and I owned a 2x DG model) would disable autofocus if it went above f5.6. However, the new DGX series TCs do not disable autofocus.

Ok, this contradicts what I've read before, but I guess I believe you since you have a 7d. To make dead sure: We are talking about the "Kenko 1.4X PRO 300 Teleconverter DGX for Canon EOS Digital SLRs", are we:

http://www.amazon.com/Kenko-1-4X-Teleconverter-Canon-Digital/dp/B002C6QC3E/ref=sr_1_1?ie=UTF8&qid=1332344013&sr=8-1

 

[brianwallace21]

Ok, this contradicts what I've read before, but I guess I believe you since you have a 7d. To make dead sure: We are talking about the "Kenko 1.4X PRO 300 Teleconverter DGX for Canon EOS Digital SLRs", are we:

http://www.amazon.com/Kenko-1-4X-Teleconverter-Canon-Digital/dp/B002C6QC3E/ref=sr_1_1?ie=UTF8&qid=1332344013&sr=8-1

That's the one!