1.4x Extender iii function

[Birdeye]

I purchased the 1.4x Extender iii to use with a Canon 70D and the Canon EF 100-400mm f/4.5-5.6L IS II USM lens. I am not able to find setting for which the AF will work when looking through the viewfinder. The AF will work in live view. My question is will these three components ever allow AF without live view? A second question is will AF work with these components if a 7D II camera body is used instead of the 70D? 

[Waddizzle · Accepted solution]

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@Birdeyewrote:

I purchased the 1.4x Extender iii to use with a Canon 70D and the Canon EF 100-400mm f/4.5-5.6L IS II USM lens. I am not able to find setting for which the AF will work when looking through the viewfinder. The AF will work in live view. My question is will these three components ever allow AF without live view? A second question is will AF work with these components if a 7D II camera body is used instead of the 70D? 

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When you use an extender, you get the benefit of apparent extended focal length.  Since nothing in life is free, the price you pay is that the minimum aperture range of the lens being used gets raised by one full stop.  Your f/4.5-5.6 lens becomes a f/6.3-8 lens.

A check of the specs show that the 70D does not have AF points sensitive enough to focus at a minimum aperture smaller than f/5.6.  Remember, a lens focuses at its’ widest aperture, and then stops down to take a photograph.  When using the adapter, the widest aperture is at 100mm, and the value would be f/6.3.  At 400mm, the widest aperture would be f/8.  These aperture values are too narrow for your 70D to auto focus.

Some of the high models have a center AF point that is sensitive at f/8.  The 7D2 is one of those camera bodies with a center AF point that is sensitive at f/8.  This means when the EF 100-400mm f/4.5-5.6L IS II USM + EF1.4x III is used with the 7D2, you will see only one available AF point, although the 7D2 will allow the surrounding AF points to act as focus assist points, effectively expanding the AF coverage of th single AF point.

For the record, it is my understanding that the lens/extender combo will allow a row of 9 AF active AF points on the 1Dx Mark II.  For comparison, the 80D will allow three rows of 9 AF points, as will the 6D2 and the 77D.

[MikeSowsun]

Like most consumer grade DSLR's, your 70D needs a minimum of f/5.6 for phase-detection Auto Focus. That is why the 100-400 1.4x combo won't work for you. You will need to uograde to a 5D Mark III, 7D Mark II, or 80D in order to AF at f/8

[Birdeye · Accepted solution]

Thank you MikeSowsun and Waddizzle! Your explanations are clear and very helpful I am certain others will benefit as well from your responses. By the way, your information is much more to the point and understandable than what I received from Canon tech support. I am veryhappy I posted my query here. 

[diverhank]

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@Birdeyewrote:

Thank you MikeSowsun and Waddizzle! Your explanations are clear and very helpful I am certain others will benefit as well from your responses. By the way, your information is much more to the point and understandable than what I received from Canon tech support. I am veryhappy I posted my query here. 

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Of course if you want this to work (albeit sluggishly), you can tape some of the pins on the 1.4X.  You can google how to do it easy enough.

[Birdeye]

Thanks diverhank! I've read about this online and have wondered if equipment could be damaged that way. Also, setting the lens to manual works better than live view -- I photo birds and the eye must be in focus or you really don't have a picture (hence my user name). Yet birds don't always wait for manual focus (hence my dilemma).

[diverhank]

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@Birdeyewrote:
Thanks diverhank! I've read about this online and have wondered if equipment could be damaged that way. Also, setting the lens to manual works better than live view -- I photo birds and the eye must be in focus or you really don't have a picture (hence my user name). Yet birds don't always wait for manual focus (hence my dilemma).

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No there should be no damage, at least it never damages my camera/lens.  By taping the pin, the lens can't report the aperture to the camera and it continues to focus...the camera is programmed to stop focus, not that it can't.  I used to do this all the time when I had the 50D that can't focus at f/8.

By the way, I believe that live view focus still works for f/8. For non-moving birds, that should work really well.

[ebiggs1]

"Yet birds don't always wait for manual focus (hence my dilemma)."

And, at one time we didn't have AF on any lens or camera.  Guess what?  We got the photos anyway.  It can be done! 

[Birdeye]

ebiggs1: Yes, indeed. I began with a Canon AE1 in 1978 however none of my bird photos from the film days compare with what digital today can do. I find on the bird websites some incredible shots from average photographers. Most people who take bird photos today are birders who carry a camera, or "guy with camera" in he vernacular of some photographers, yet they get really good photos. And, with digital we can take far more photos today that we could with expensive film thus increasing the probability of an accidental good capture.  Back in the time you are talking about most of the good photos were taken by photographers, like Eliot Porter, or ornithologists who spent a lot of time with cameras (e.g. Arthur A. Allen, Chester A. Reed, William Lovell Finley, and R. W. Shufeldt) rather birders with cameras. More recently, 1990s, Bill Burt has taken some outstanding photos of birds on film. 

[RobertTheFat]

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@ebiggs1wrote:

"Yet birds don't always wait for manual focus (hence my dilemma)."

And, at one time we didn't have AF on any lens or camera.  Guess what?  We got the photos anyway.  It can be done! 

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Yeah, but cameras in those days had manual focusing aids that most current cameras lack. My Nikon F-2 had a split-image rangefinder and a Fresnel ring built into the viewfinder. None of my digital cameras have had anything comparable.

[Birdeye]

Good point! I had forgotten about the split image. We got by not know anything about the coming technology. I wonder what is around the corner that we can not now concieve. Will we be saying some day that all we had was a hunting AF? 

I hope, RobertTheFat, that you are weathering the bomb cyclone. 

Birdeye

Bozeman, MT