Autofocus with telconverters on 10D

[CyberDyneSystems]

I remember reading somewhere that you can "force" an EOS to try and autofucus with a lens and converter that would otherwise be too stopped down, by taping over one of the electronic contacts on the teleconverter.

Does anyone know which contact,. or if this is even truue?

[chris maddock]

http://www.fredmiranda.com/TipsPage/

It does work, although all it actually does is to stop the AF being disabled. it doesn't miraculoulsy give perfect AF with a lens/TC combination that is out of spec for the camera. My 100-400IS, 1.4x Extender and D30 get on pretty well provided the light is good enough.

Just one point - that article suggests taping the pins on the extender. Doing that works fine with my 100-400 but caused my 70-200/f4 to be very poor at focussing with the 1.4x - it hunted a lot. I found that removing the tape means the 70-200/f4 and 1.4x now focus as quickly and reliably as without the extender. Accordingly, I've shifted the tape to the back of the 100-400, not the front of the extender.

KRs
Chris

[CyberDyneSystems]

Thanks Chris :)

...and as I would use the extender on more than one lens (including a 70-200 f/2.8 that LOVES the extender),. I will do the same :)

[dchan1212]

Hi Chris,

I was curious as to which 1.4x teleconverter you are using. I have ordered a 70-200mm f/4 from B&H for my 10D and am debating between the Kenko Pro 300 and the Canon 1.4x II for the L lenses. The price difference is about $100. Any thoughts on either one?

Thanks, David

[chris maddock]

Hi David,

Mine is the Canon 1.4x Extender, Mk I.
I've no real knowledge about any other - unless you count a genuine "el-cheapo" shop-brand 2x that I was daft enough to buy some years ago ;-)
AFAIK the main difference between the 1.4x I and the 1.4x II is more enviromental sealing on the later one, I don't think the optics were changed.

I do know that not all extenders have the extra contacts that cause the camera to know the overall max aperture, so not all may need the tape trick. My 2x doesn't and it was some time (I didn't have the canon 1.4x then) before I twigged quite what people were talking about with the tape trick ;-)

KRs
Chris

[dchan1212]

Hi Chris,

Thanks for the info. So I take it that you really like your Canon 1.4x! I am still debating between that and the Kenko but either one will be a much cheaper alternative to the reach afforded vs. buying a new lens in its place. As for the contacts, I think the Kenko may NOT have the pins that sense aperture. Nor does it have the little "nub" that the Canon has that will only limit you to using it with L lenses. Again, thanks.

David

[chris maddock]

Hi David,

I certanly do - despite it only fitting two of my lenses ;-)

Check out the list of lenses that the Canon will fit (Canon's website will tell you). If you don't have, or don't intend to get, many lenses from that list (or intend to get other makes, which it might not fit) then the Kenko would probably be a better bet for you.

KRs
Chris

[CyberDyneSystems]

Dchan,..

I would not put that fine peice of Canon "L" glass on the Kenko,.. I'm not knocking the Kenko,. as I have no expeirience with it,. but you were concerned enough about your equipment to get a really high quality Canon lens,. it seems an odd choice to then trust the Kenko to maintain that image quality.

[ctgoldwing]

dchan1212 wrote:
Hi Chris,

I was curious as to which 1.4x teleconverter you are using. I have ordered a 70-200mm f/4 from B&H for my 10D and am debating between the Kenko Pro 300 and the Canon 1.4x II for the L lenses. The price difference is about $100. Any thoughts on either one?

Thanks, David
David I was able to pick up a 1.4x Canon extender in exclnt condition on ebay for abt $150. Just takes some patient lurking - lol!
Jerry

[CyberDyneSystems]

ctgoldwing wrote:

David I was able to pick up a 1.4x Canon extender in exclnt condition on ebay for abt $150. Just takes some patient lurking - lol!
Jerry

AAARRRGGHHH!

I am bidding on one myself NOW!!!

If I see any of your names bidding on it I'll be pissed :D :D Kidding! :)

[dchan1212]

Thanks Guys! Your comments have been very, very helpful. I posted a similar post at dpreview.com and got similar answers. Most people do point towards the Canon 1.4x. You do get what you pay for so I think I will seriously consider it. My only worry is compatability with other lenses. I only mentioned the Konko Pro 300 because some people liked it and it allows freedom of compatability with all EOS tele lenses by Canon, Sigma, Tamron and so on. But the sharpness of the Canon 1.4 is too tempting. Darn! Thanks so much again guys.

david