Dumb Newbie Question..Lose AF using Extender?

I have gotten mixed results from using google.

If I add a 1.4 Extender onto a Canon 70-200 L F4 while using a 1D Mark II will I lose Auto focus abilities?

AF should work fine

Where you run into problems is when you extend a lens that's already f/5.6 or slower, like the long end of a consumer zoom. Many bodies need at smallest f/5.6 effective to AF; at least some of the 1-series goes to f/8.

The 1D bodies can AF down to f/8 so it's good. And, I often stop down to f/11!

Just a quick note all canon bodies will focus with the lens (and tc combo) wide open.
They only stop down at the time of the shot.

Yep, you'll even get AF(center point) with a 2x TC as well..albeit slow. Enjoy!

Awesome thank you guys,

Does anyone have any samples of a 70-200 with either a 1.4 or 2 extender on it?

Thanks!

tonylong wrote in post #12173042
The 1D bodies can AF down to f/8 so it's good. And, I often stop down to f/11!

You should know that stopping down doesn't change the max aperture. Digital cameras stay at the max aperture until right when you take the picture, then the diaphragm closes down to the correct aperture, and they releases back to max aperture right after, so you are always looking through max aperture so you have the brightest view finder. The only time you see through a stopped down aperture is if you use the DOF preview button.

So, your autofocus is always focusing via f/8, not f/11.

However, if you put a 2x TC on a f/5.6 lens making it a max aperture of f/11, it will not AF.

OP, you have a 1 series body, so you will have autofocus in your center point even if your max aperture is as slow as f/8, however, it will not be very fast or all that accurate. A max aperture of f/5.6 or faster will allow you to retain all autofocus functions.

So basically, do not use a 1.4x TC on a lens unless it is f/4 or faster and do not use a 2x TC on a lens unless it is f/2.8 or faster (to maintain f/5.6, at least).

Since you have a 70-200 f/4, a 1.4x TC would work just fine.

Thank you for the info Revo.

One last question and I will leave you folks alone for a day or two .

I see that with the 1.4 their is either the II or III the III is also more expensive. Is the III worth the extra cash?

Well, the IIIs are reportedly quite good, but I don't have one to test it out against the IIs.

HabertPhotography wrote in post #12174292
Thank you for the info Revo.

One last question and I will leave you folks alone for a day or two .

I see that with the 1.4 their is either the II or III the III is also more expensive. Is the III worth the extra cash?

The version III TC's are the most recent ones, and offer the latest and greatest. They help preserve image quality a little and also have a different chip which supposedly aids in autofocus accuracy. Autofocus speed is the same with both version II and III extenders - the 1.4x extender reduces AF speed by 50%, while the 2x reduces it by 75%. The reduction is speed is suppose to aid accuracy.

You see a much better improvement when going from II to III only when using "IS II" lenses, such as the 70-200 2.8 IS II (the only IS II lens currently out - 300mm f/2.8 IS II and 400mm f/2.8 IS II as well as a few other IS II super telephotos are on the way.

Honestly, I'd just stick with the version II. You can find one used on the forums for ~$225. I don't think it's worth the extra $250+ for the III unless you are using a new IS II lens. I have a 70-200 IS II and I opted for the III version since the difference is quite significant with that particular lens, and I plan to use the TC quite a bit (and I figured if I already invested so much into the lens to get that IQ, might as well invest some into the TC to retain it).