100-400mm Lseries and new 2x Canon tele-extender

[stegosaurus]

I can't get the 100 - 400mm L series and 2X Canon tele extender to auto focus.  Is this something that will ne manual only?  I recently purchased the Extender 2x III since it is "fully compatable"  Is there a autofucus mode that will work.  I have the ISO set so that I have it fully open.

[cicopo]

It won't AF on the majority of cameras with a 1.4 TC due to design limits in the camera. The Pro bodies & 5D3 can AF at F8 but those are the only bodies that can. Your lens with a 2 X TC is at f11 wide open.

[stegosaurus]

Thanks, I am using a 5D 3 but you're right it's f11 with the 2 stop loss. Thanks

[amfoto1]

5D Mark III with the latest firmware is limited to f8 aperture or larger, for AF to work. And that will only be with several of the center AF points. (The 5DIII is the only non-1D series camera to offer this, all others require f5.6 or larger.)

As mentioned, putting a 2X (that "costs" two stops of light) on the 100-400mm f4.5-5.6 makes that into an effective 200-800mm f9-f11 lens. So when that registers with the camera,  AF is turned off.

You can try taping up a couple of the electronic contacts on the TC or lens (Google for info on which ones to tape), so that the camera doesn't know the TC is there and will try to focus. However, to be frank, I wouldn't expect AF performance to be very good or for the image quality to be all that great. In general, teleconverters work better with prime lenses than with zooms.

Alternatively, you could just try to manually focus, except your viewfinder will be pretty dim (and, like most modern AF cameras, isn't very "manual focus friendly"). It might help to use Live View with Exposure Simulation enabled and the image magnified.... but this will be relatively slow to work with.

Or, swap the 2X for a 1.4X (that "costs" one stop of light)... to  make the lens TC combo an effective 140-560mm f6.3-8, so your camera should still be able to AF, though perfomance may drop off a bit. I'd still be concerned about image quality, but haven't tried it personally and different combos of TC and zooms can work better or worse.

Note: Changing the ISO or even the selected aperture makes no difference what-so-ever. All EF lenses are maintained wide open at their rated aperture until the moment of exposure, when they stop down very briefly during exposure, then immediately after exposure re-open to give the brightest view possible (hence the need for a Depth of Field preview button to see how DOF will be with any particular aperture other than wide open).

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Alan Myers

San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
FLICKR & PRINTROOM 

[ebiggs1]

Again, IMHO, tele converters are a bad idea.  I got 4 or 5 of them around here and tried to use them and yeah they work, I guess. The 1.4 is more usable but still you give to get.

The best solution is a 7D. I use my 600mm f4 on my 7D and reap the no loss benefits of the 1.6 crop factor. BTW, a 7D is way cheaper than buying a 600mm Canon lens.

My 100-400mm, on my 7D, yields a 160-640mm lens and there is not f-ratio loss! The 600mm is a whopping 960mm! 

[stegosaurus]

I have a 7D also.  Wanted to compare with my 5D III that I got recently.  I agree with you but thought that carrying the extender and the 70 -200 would lighten my pack for a quick airline trip without serious photos (Navy reunion trip)

[Robifumi]

I bought a 2x converter to try with my 7D and 100-400MM IS USM but have the same problem, no autofocus, its pretty useless without AF as I mainly photograph motorbike racing, is it worth trying the tape up option or better to get a 1.4x converter? cheers 

[cicopo]

In general BUT based only on what I've read (never tried this) adding a TC slows down the AF which suggests that shooting action through a TC will have a very low keeper rate in the best of light. If you need a longer lens for the action you shoot right now I think you should research the new Sigma 150-600's. I've seen some aviation samples that looked very good.

[amfoto1]

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@Robifumi wrote:

I bought a 2x converter to try with my 7D and 100-400MM IS USM but have the same problem, no autofocus, its pretty useless without AF as I mainly photograph motorbike racing, is it worth trying the tape up option or better to get a 1.4x converter? cheers 

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Why would you need more than about 400mm on a crop sensor camera like your 7D? 400mm is already an extremely long focal length on that camera. 400mm + 2X = 800mm would be insanely long, very hard to hold steady for a shot and you'll lose a lot of image quality just to all the atmosphere you'll be shooting through, in additon to the IQ that's lost to even the best 2X. I shoot a lot of sports and rarely use longer than 300mm (also with 7D), though occasionally I'll put a 1.4X on it. I have 500mm, but it's usually just too long... I tend to use it more for small wildlife at a distance, rather than sports.

Maybe you should just get closer and/or concentrate on shooting what's within reasonable reach?

If you really need more reach, hey there's the Canon EF 200-400/4L 1.4X IS USM that has a built-in, dedicated and optically-matched 1.4X teleconverter. Of course it costs about $11,000 USD.... But a 200/2.8, 300/4, 400/4, and 500/4 would cost close to $20,000, wouldn't be as fast and convenient as a zoom, plus one big zoom owuld be a lot easier to haul around.

***********
Alan Myers

San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
FLICKR & PRINTROOM