Teleconverter to use with 100/400 f/4.5-5.6L IS

I have the 100/400L, which is a great lens that I use with my 20D, and I'd like to get some more reach without laying down several grand. A TC seems the obvious solution.

But according to what I've read, autofocus won't work with the 100/400L using the Canon 1.4x TC. But I've also read that the Canon 2x TC (which apparently autofocus WILL work with) sucks, image quality-wise.

I haven't had good experiences with third party TCs in the past, but that wasn't with a Canon.

Any advice here? Image quality (sharpness) is my top consideration, and I really need autofocus. Is the Canon 2x really that bad? Are any of the 3rd party TCs any good? Will AF work with them? What do you recommend?

Thanks
--
Tony Dunn
http://www.adunnphotography.com

Tony Dunn wrote:

I have the 100/400L, which is a great lens that I use with my 20D,
and I'd like to get some more reach without laying down several
grand. A TC seems the obvious solution.

But according to what I've read, autofocus won't work with the
100/400L using the Canon 1.4x TC. But I've also read that the Canon
2x TC (which apparently autofocus WILL work with) sucks, image
quality-wise.

Not correct on both counts - image quality with the 2x can be good, but not with the 100-400, which is too slow, and not sharp enough (it works best with sharpest primes like the 300/2.8 L). AF will NOT work with the 2x and 100-400.

This lens can AF with a 3rd party 1.4x TC or with the Canon 1.4x TC with some pins covered/taped.

misha wrote:

Not correct on both counts - image quality with the 2x can be good,
but not with the 100-400, which is too slow, and not sharp enough
(it works best with sharpest primes like the 300/2.8 L). AF will
NOT work with the 2x and 100-400.

According to the Canon website ( http://www.usa.canon.com/app/pdf/lens/Lens_Extender_chart_new.pdf - page 2), AF does work with the 100/400 - or at least it doesn't say that it doesn't.

This lens can AF with a 3rd party 1.4x TC or with the Canon 1.4x TC
with some pins covered/taped.

Any particular recommendation on 3rd part TC? Do you know where I can get info on which pins to tape for the Canon 1.4x TC?

Thanks
--
Tony Dunn
http://www.adunnphotography.com

Taping pins:
http://www.michaelfurtman.com/taping_the_pins.htm

BTW
Link to your wildlife shots is incorrect
http://www.adunnphotography.com/galleries/index.asp

Your gallery is superb, good luck

TCs with only 7 pin contacts will allow (theoretically) AF to work. These are cheaper versions of the third party TCs. Or get a Pro version TC, Canon or Kenco/Tamron with 10 pins & cover the last 3 of them. I use a Kenco 1.4 cheaper version TC and AF works only with bright light. But it slows down AF quite a bit. AF does not work at all with 2x TC which is also a 7 pin version.
--
Gautam

Well, don't expect the AF to work as well with the TC, it just won't. The AF will work reasonably well in well lit conditions and it can be terribly slow (or not focus at all) and thus frustrating in low light. Using a TC is a cheap way to increase your reach but there are shortcomings as I have mentioned. I do believe you will also loose 1-1/2 f/stop if I'm not mistaken and a slight decrease in sharpness.
100% crop 100-400L IS @ 400mm

100% crop + Kendo 1.4X DG PRO 100-400L IS @ 400mm

Tape these 3 pins

Tony Dunn wrote:

misha wrote:

Not correct on both counts - image quality with the 2x can be good,
but not with the 100-400, which is too slow, and not sharp enough
(it works best with sharpest primes like the 300/2.8 L). AF will
NOT work with the 2x and 100-400.

According to the Canon website
( http://www.usa.canon.com/app/pdf/lens/Lens_Extender_chart_new.pdf

• page 2), AF does work with the 100/400 - or at least it doesn't

say that it doesn't.

Maybe it does not say, but I give you a 100% guarantee that it does not work If a 1.4x does not AF, there's even (much) less of a chance of AF with 2x (because you lose 1 stop with a 1.4x and 2 stops with a 2x).
--
Misha

Tony - Others may also have written this - There are two ways - two good ways - to get autofocus to work with the 100-400 and a TC. The combo can get some really good images and is well worth trying.

First of all, with the Canon 1.4 or 2 TC, you can tape the leftmost 3 contact points on the lens (the leftmost 3 as you look at the back of the lens, contacts near you, lens pointed downward). That works fine. Place a little piece of Scotch tape or similar tape ( not duct tape please!) on those contacts, and be careful mounting the lens, so you don't wind up with that little piece of tape inside your camera.

Second, and probably just as good (though there is some argument over optical quality) you can use the 100-400 with the Kenko Pro TCs, without taping the contacts at all.

In low light, autofocus will be a little slower. I like to "prefocus" as best possible, tapping the shutter button halfway a time or two before I actually want to take the shot.

Of course there will be some loss of image quality, but the 1.4 TCs are still capable of producing very good quality images with the 100-400.

The only other way is to spend the big bucks and carry that bazooka, the 500mm lens or longer, around with you.

Bill Hansen

bill hansen wrote:

Tony - Others may also have written this - There are two ways - two
good ways - to get autofocus to work with the 100-400 and a TC. The
combo can get some really good images and is well worth trying.

First of all, with the Canon 1.4 or 2 TC, you can tape the leftmost
3 contact points on the lens (the leftmost 3 as you look at the
back of the lens, contacts near you, lens pointed downward). That
works fine.

I think you will find that with a 2x TC, even with taped pins, the lens might autofocus only in extremely bright conditions.

misha wrote:

I think you will find that with a 2x TC, even with taped pins, the
lens might autofocus only in extremely bright conditions.

I'm sure that's true, since it would be an f 11 lens. In bright light, it would work. In dim light it would be difficult or impossible to manually focus an f11 lens.

I do have experience using the 100-400 with a Canon 1.4X TC in daylight which was not bright sun. It worked well. I wouldn't argue that focus was as fast as it would have been with out the TC, or that image quality was exactly as good. That would be silly. But the combo was very very good. For those who can't afford a 500mm+ lens or who don't want to carry one around, the 100-400 with TC works well. Photographers far better than I have used it and like it.

Bill