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.

[RobertTheFat]

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@Birdeyewrote:

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

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Thanks for the thought, Birdeye. We're about 20 miles inland, so all we got was rain and occasional howling winds. It was the towns along the shore that got inundated.

[ebiggs1]

"Yeah, but cameras in those days had manual focusing aids that most current cameras lack."

Yeah, there Robert, I wonder why Canon even bothers to put a AF/MF switch on their lenses.  We are such complete boobs that we can't use it.  A poor workman always blames his tools

[RobertTheFat]

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@ebiggs1wrote:

"Yeah, but cameras in those days had manual focusing aids that most current cameras lack."

Yeah, there Robert, I wonder why Canon even bothers to put a AF/MF switch on their lenses.  We are such complete boobs that we can't use it.  A poor workman always blames his tools

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Sorry, Ernie, I wasn't trying to be argumentative or blame my tools. It didn't occur to me that you wouldn't have gotten the more elaborate focusing screen for your Nikons. If it had, I wouldn't have brought it up.

[ebiggs1]

"...much more to the point and understandable than what I received from Canon tech support"

I am curious?  What did Canon tell you?  They usually are pretty good and through.  If you happen to get a bad one just hang up and call right back  They have some great people.

[Birdeye]

ebiggs1: Yes, I have called Canon tech support before and have been satisfied with the answers. This time around however I got a guy who did not leave me with a lot of confidence in the correctness of what he said. His answers did not explain things in the technical terms of the two good responses, Mike Sowsun and Waddizzle, I received here. He tried so I don't wish to bash him. 

[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? 

---

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.

[PLee]

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@Waddizzlewrote:

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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? 

---

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.

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The bolded comment is not correct and I wanted to clarify. Both the EOS-1D X Mark II and EOS 5D Mark IV support full time AI Servo AF with all 61 AF points when using the EF 100-400mm f/4.5-5.6L IS II USM with the Extender EF 1.4x III. Note that this functionality is not necessarily maintained especially with older long glass combined with older version extenders. In the OP's lens and extender scenario, the EOS 6D Mark II, EOS 80D and EOS 77D will support 27 points for AF out of their 45 point arrays at f/8. Access to a larger array of points in AI Servo can clearly have significant advantages for focusing on difficult to track subject matter and modern Canon EOS DSLRs offer a lot of that functionality.

[Waddizzle]

“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.


The bolded comment is not correct and I wanted to clarify. Both the EOS-1D X Mark II and EOS 5D Mark IV support full time AI Servo AF with all 61 AF points when using the EF 100-400mm f/4.5-5.6L IS II USM with the Extender EF 1.4x III. Note that this functionality is not necessarily maintained especially with older long glass combined with older version extenders. In the OP's lens and extender scenario, the EOS 6D Mark II, EOS 80D and EOS 77D will support 27 points for AF out of their 45 point arrays at f/8. Access to a larger array of points in AI Servo can clearly have significant advantages for focusing on difficult to track subject matter and modern Canon EOS DSLRs offer a lot of that functionality.”

Actually, I do not own a 1Dx Mark II, and what you described was my assumption, that all AF points should be active.  But, I was corrected, and told differently, that only a single row of 9 AF points will be active with this particular lens/extender combo.