When will canon fix the focus issues with the 70D?

[Photogirl55]

I was "T.H.I.S." close to buying the 70D.  I have read WAYYY too many posts about issues with the focusing on the 70D.  How is Canon handling the issue?  I would love to buy this camera, but not willing to gamble with that much money.

[Molybdo42]

I already use back button AF ; know the difference between one shot, Ai servo, and AI focus ; know when to use micro focus adjust, etc...

For the moment I'm more interested in knowing what the 19 point AF sensor sees when aimed at different objects (the raw data). The focus sensitive areas extend beyond the marks in the viewfinder and sometimes (like in my picture above) the camera focuses where I don't want to. I want to know what caused that.

One thing I still don't understand is when I look at pictures of the AF sensor, compared to the focus point distribution it looks completely different. What do those sensors see ?

I would also like to know what other sensors Canon might use. For example can they use the data from the exposure metering when doing AF ? Is there a different focus algorithm when using different focal length.

How does the raw signal measured by the AF sensor changes between a wide angle lens and a telephoto lens ?

I'm doing this mainly to know the limitations of my gear. I missed some nice shots because I wasn't aware of these limitations. This knowledge will also assist me in getting the most suited gear for my shooting style.

The only references I found were these :

http://fr.wikipedia.org/wiki/Autofocus_%C3%A0_d%C3%A9tection_de_phase

http://www.clarkvision.com/articles/understanding.autofocus/

Higher end cameras from Canon offer more customization options but they are so heavy and lack some features that make the 70D attractive : touch screen, swivel screen, dual pixel AF, weight...

[TTMartin]

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@Molybdo42 wrote:

I already use back button AF ; know the difference between one shot, Ai servo, and AI focus ; know when to use micro focus adjust, etc...

For the moment I'm more interested in knowing what the 19 point AF sensor sees when aimed at different objects (the raw data). The focus sensitive areas extend beyond the marks in the viewfinder and sometimes (like in my picture above) the camera focuses where I don't want to. I want to know what caused that.

One thing I still don't understand is when I look at pictures of the AF sensor, compared to the focus point distribution it looks completely different. What do those sensors see ?

I would also like to know what other sensors Canon might use. For example can they use the data from the exposure metering when doing AF ? Is there a different focus algorithm when using different focal length.

How does the raw signal measured by the AF sensor changes between a wide angle lens and a telephoto lens ?

I'm doing this mainly to know the limitations of my gear. I missed some nice shots because I wasn't aware of these limitations. This knowledge will also assist me in getting the most suited gear for my shooting style.

The only references I found were these :

http://fr.wikipedia.org/wiki/Autofocus_%C3%A0_d%C3%A9tection_de_phase

http://www.clarkvision.com/articles/understanding.autofocus/

Higher end cameras from Canon offer more customization options but they are so heavy and lack some features that make the 70D attractive : touch screen, swivel screen, dual pixel AF, weight...

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FWIW, I think BBF is overrated. I reprogram the AF ON button, to be an AF OFF button and use that to stop focus when needed in AIServo.

This is from the classic 7D, but, since the AF sensors appear to be very similar it should answer your question. He also explains his methodology if you want to duplicate it with your 70D. By the way this was originated by someone who had a very similar complaint about the classic 7D's AF that you have with the 70D.

Cross type AF points in EOS 7D * all 19 points are shown by rolling over the list below the 4th photo

Again not a 70D reference, but, a 7D Mk II. On pages 32, 33, and 34 you can see a list of what lenses work with what AF points. Not all lenses can use all 65 of the 7D Mk IIs AF points. Like you surmised wider angle lenses like the EF-S 10-22mm f/3.5-4.5 USM and the EF-S 10-18mm f/4.5-5.6 IS STM are lenses that have a reduced number of usable AF points. While this doesn't directly address your issue with the 70D, it does show that your thinking is on the right track.

EOS 7D Mark II AF-Setting Guidebook * link to PDF is on the lower left portion of the page 

[KeithR]

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@70Downer wrote:

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Stop spreading BS misinformation.  A potn poll showed that well over 10% of the 70D's on that forum were having focus problems. 

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Nope.

It was 10% of those that clicked the poll - a self-selecting bias if ever there was one. My 70D is superb, I'm on POTN, but I never saw the poll...

And then we deal with all the "what ifs" TT mentions...

Besides - and this is a question I've asked umpteen times without getting a straight answer from the anti 70D lobby.

There's all this noise about the 70D having a particular AF problem with the lens at f/2.8 or wider.

All DSLRs meter and focus with the lens wide open: so every single image taken with an f/2.8 or wider lens is focused at f/2.8 or wider, no matter how much the lens is stopped down.

How can that be? How can an AF problem exist at f/2.8 but go away at f/5.6, if every shot is actually taken at f/2.8?

I'll tell you: because there's no f/2.8 AF problem. Every example I've ever seen of this "problem" was actually a misunderstanding about DoF, pure and simple.

And yet here you are. rolling the same drivel out yet again. And you have the nerve to tell TT to stop spreading "BS misinformation"!   

[KeithR]

"All my pictures with the Viewfinder are blurred while they are sharped with the Live viewer."

So AFMA the camera!

[TTMartin]

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@KeithR wrote:

"All my pictures with the Viewfinder are blurred while they are sharped with the Live viewer."

So AFMA the camera!

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This is correct micro focus adjustment should correct your issue.

Because you have to do micro focus adjustment does NOT mean there is anything wrong with your camera.

Please read this to understand why - "This lens is soft" and other myths ~ by Roger Cicala, lensrentals.com

[Matt8275]

Hi Keith, 

Then you think that for all the people who have the same issues with their 70D autofocus, the solution is the AFMA ?

https://www.youtube.com/watch?v=cA6JnzYSDJE

https://www.youtube.com/watch?v=-bx9povjPtI

http://photography-on-the.net/forum/showthread.php?t=1354075

Seriously ?  

[TTMartin]

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@Matt8275 wrote:

Hi Keith, 

Then you think that for all the people who have the same issues with their 70D autofocus, the solution is the AFMA ?

https://www.youtube.com/watch?v=cA6JnzYSDJE

https://www.youtube.com/watch?v=-bx9povjPtI

http://photography-on-the.net/forum/showthread.php?t=1354075

Seriously ?  

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The Toby one definitely. In fact after he micro focus adjusted he didn't have an issue with the camera and most of the lenses. The one or two he still had issues with were likely a lens issue, not a camera issue, since MFA correct the 'issue' with some lenses. Unfortunately Toby seemed to misunderstand the real issue that some people had with a few early cameras in Germany and perpetuated a myth that you should have to micro focus adjust your camera

MichaelTheMentor one says it is not an issue and that micro focus adjustment did correct it for him. You probably shoud have watched that one first, before posting it.

The photography-on-the.net one links to a video of the very few early cameras that were limited to Germany that really did seem to have an issue. The real issue was that after micro focus adjustment, the center phase detect AF point focused differently than the other phase detect AF points.

It is perfectly normal to need micro focus adjustment for phase detect AF to match the live-view contrast detect or dual pixel AF.

Again, please read this to understand why - "This lens is soft" and other myths ~ by Roger Cicala, lensrentals.com

[macdaddy]

The defenders of this issue are simply full of it.  When I am able to attain clean and accurate focus using any of the viewfinder squares OTHER than the center square not matter the MFA performed, then there is an issue with the camera.  I've been able to replicate the issue with two Canon and one Sigma lens.  Canon Service refused to acknowledge there was an issue on my body.  So when I want no questions asked quality results, I try to use the live view as much as possible.  And if I am forced to use the viewfinder (to use remote flash because I can't afford Canon's that will work with liveview), I have to use any of the focus squares other than the center one.

To claim that MFA fixes an issue that is limited to a single, but most used, square is simply ridiculous.

[TTMartin]

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@macdaddy wrote:

The defenders of this issue are simply full of it.  When I am able to attain clean and accurate focus using any of the viewfinder squares OTHER than the center square not matter the MFA performed, then there is an issue with the camera.  I've been able to replicate the issue with two Canon and one Sigma lens.  Canon Service refused to acknowledge there was an issue on my body.  So when I want no questions asked quality results, I try to use the live view as much as possible.  And if I am forced to use the viewfinder (to use remote flash because I can't afford Canon's that will work with liveview), I have to use any of the focus squares other than the center one.

To claim that MFA fixes an issue that is limited to a single, but most used, square is simply ridiculous.

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What you describe is different than what the previous poster described. 

If you MFA your center AF point, and then repeat the MFA process for each surrounding AF points and you have MFA settings that vary by more than 8 from the center AF point and the surrounding points you may have one of the very few cameras that actually have an issue. 

While your camera may actually have a problem, not everyone does. 

It is perfectly normal for AF to vary between Liveview AF and the Viewfinder's PDAF. It is not normal for AF to vary substantially between different viewfinder PDAF focus points. These are two different things.

The problem is that far to many people misinterpret the perfectly normal difference between Liveview AF and the Viewfinder's PDAF as being a problem with the 70D's AF.

[Dobbsincrete]

1. Sorry to be a pain on this issue, but to me (not a professional photographer), the viewfinder is the preferential method of viewing the subject, the monitor is for viewing the photograph taken. In the case of the EOS70D, the articulated screen does give you the added ability to view the subject from those difficult angles that would be impossible looking through the viewfinder. Now Canon have produced a camera where using the viewfinder does not take such a good picture. That can't be right can it?