'Revolutionary' Dual Pixel AF Explained

[Canon Rumors]

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<p><strong>Dual Pixel CMOS AF will change —High Image Quality” the basic assumptions about Digital SLRs

</strong>Canon USA has posted a PDF explaining the “revolutionary” Dual Pixel AF technology.</p>
<p><strong>Introduction</strong>

This is not just a new technology. It is a revolution that will significantly expand the possibilities of DSLR cameras.</p>
<ul>
<li><em>“The correct way to take photos is by looking through an optical viewfinder and shooting”</em></li>
<li><em>“Live View is a subsidiary function, inferior to the optical viewfinder”</em></li>
<li><em>“The DSLR’s movie mode is so difficult, as to be usable only by a professional”</em></li>
</ul>
<p>Dual Pixel CMOS AF is a new technology that will cast aside these assumptions. The entire surface of the sensor is lined with pixels composed of two photodiodes each, and the image plane phase-difference detection AF focuses using the phase-difference of the two parallax images.</p>
<p><strong><a href="http://www.learn.usa.canon.com/app/pdfs/articles/Canon_Developers_Interview_nonfacing_pressquality.pdf" target="_blank">Read The Entire Article</a> | <a href="http://www.bhphotovideo.com/c/product/986389-REG/canon_8469b002_canon_eos_70d_dslr.html/bi/2466/kbid/3296" target="_blank">Canon EOS 70D at B&H Photo</a></strong></p>
<p><strong><span style="color: #ff0000;">c</span>r</strong></p>

 

[Lee Jay]

The supported lens box has some very disconcerting information. I'm wondering about 3rd party lenses that should work but will be in contrast-detect just because they aren't "supported". Also, what's the point of having this function work at f/11 if it doesn't work with teleconverters? Who has a "supported" bare f/11 lens?

 

[bsbeamer]

I think this is just the start of a "new wave" of better quality STM lenses on the way to work with this AF technology... not sure if they'll get to the "L" series with STM, especially at the price point of the capable camera bodies, but just below that would be welcomed by many and there would be a market for them, if this AF works as promised. (Though the C100 can work with STM lenses apparently, maybe the C300 as well?)

Interesting developments for sure...

 

[Mt Spokane Photography]

I think this is just the start of a "new wave" of better quality STM lenses on the way to work with this AF technology... not sure if they'll get to the "L" series with STM, especially at the price point of the capable camera bodies, but just below that would be welcomed by many and there would be a market for them, if this AF works as promised. (Though the C100 can work with STM lenses apparently, maybe the C300 as well?)

Interesting developments for sure...

The STM lenses were made to smooth out AF for Video. With the Dual Pixel system, that is no longer a problem to be solved, so STM lenses will continue to be built because they are cheaper to make.

 

[jonjt]

I'd like to see how Sigma and Tokina are going to deal with this. My 11-16 and my 85/1.4 are both lenses and, I'd hate for them to be made unusuable.

 

[dstppy]

My takeaway from this is that they're eventually going to produce a mirrorless that has a 'viewfinder' that eventually will work as well as an optical viewfinder . . .

Meh for now.

Cool for later. Progress is progress

 

[3kramd5]

If the entire sensor is capable of phase detect, why are there still discrete autofocus points? What keeps them from using a touch screen to say "focus here"?

 

[bchernicoff]

If the entire sensor is capable of phase detect, why are there still discrete autofocus points? What keeps them from using a touch screen to say "focus here"?

I believe they demoed exactly that in some of the 70D promo videos.

 

[Marsu42]

Thanks for explaining why this dual pixel af doesn't provide any significant step forward to what I do...

* I like to shoot through an (o)vf, and with heavier lenses everything else is non-practical except ...
* When on mono-/tripod in lv I use mf with Magic Lantern's focus peaking (and raw zebras/histogram)
* I don't do video, for my 2ct they could release a non-movie 6d w/ a lower price

 

[Timothy_Bruce]

Thinking about every pixel being used für phase-detection-AF, so also there will be the Bayer filter in front of them making the AF system able to recognize the color of the AF-subject.
So this could lead to a really good hold on to AF-Servo-targets when there is a Color Difference towards the background or obstacles.

Maybe the next 1D will have an AF sensor of this type... think of an viewfinder-AF with 10.000.000 AF-Points and an intelligent binding system with a dot-matrix lcd overlay...

 

[Drizzt321]

Thanks for explaining why this dual pixel af doesn't provide any significant step forward to what I do...

* I like to shoot through an (o)vf, and with heavier lenses everything else is non-practical except ...
* When on mono-/tripod in lv I use mf with Magic Lantern's focus peaking (and raw zebras/histogram)
* I don't do video, for my 2ct they could release a non-movie 6d w/ a lower price

Not going to happen. At this point it's an expected feature checkbox for new DSLRs to have a movie mode. Frankly, it wouldn't make economic sense for them to. They'd need 2 separate tooling lines for the body with the switch to movie mode, and one without. Plus they'd need to maintain 2 separate firmwares, one with movie support and one without.

 

[meli]

The supported lens box has some very disconcerting information. I'm wondering about 3rd party lenses that should work but will be in contrast-detect just because they aren't "supported". Also, what's the point of having this function work at f/11 if it doesn't work with teleconverters? Who has a "supported" bare f/11 lens?

Perhaps 3rd party lenses wont have a problem after all, here is a preview of a 70d with a 18-35 sigma performing splendidly apparently:

Canon 70D Review + Sigma 18-35mm f1.8 lens preview

 

[viggen61]

If the entire sensor is capable of phase detect, why are there still discrete autofocus points? What keeps them from using a touch screen to say "focus here"?

The phase detect on the sensor only works with the mirror up, and is seamless across the image. With the mirror down, using the viewfinder, you're still using the "old" phase detect system, which still requires the discrete points.

 

[justsomedude]

I think the Dual Pixel AF is indeed revolutionary, and posted up my opinions on this a couple of weeks ago when the 70D was launched.

On a side note, it's nice to see Canon back at innovating new technology and pushing the industry forward. I was a little worried after the 5D3-vs.-d800 forum angst last year, but clearly Canon is responding. Next up... the 75mp body everyone's itching to see!

Thanks, Canon, for getting back on track!

 

[gruhl28]

The supported lens box has some very disconcerting information. I'm wondering about 3rd party lenses that should work but will be in contrast-detect just because they aren't "supported". Also, what's the point of having this function work at f/11 if it doesn't work with teleconverters? Who has a "supported" bare f/11 lens?

I'm concerned about the 100mm f/2.8 Macro (non-IS), which I own. This is a currently sold lens, and the document said that dual pixel would support all current lenses, but the macro is on the list of lenses that are not fully supported. This seems like a contradiction. This is the only high quality current lens that I noticed on the list that is not fully supported.

 

[sandymandy]

Am i the only one who prefers shooting with the optical viewfinder, even if live view is tzhe same speed? I think its not long anymore til Canon only releases only mirrorless cameras if the AF speed is the same. And then people like me can pay another 899$ or whatever for an electronic viewfinder

 

[photonius]

The supported lens box has some very disconcerting information. I'm wondering about 3rd party lenses that should work but will be in contrast-detect just because they aren't "supported". Also, what's the point of having this function work at f/11 if it doesn't work with teleconverters? Who has a "supported" bare f/11 lens?

As pointed out, each lens has to be calibrated. based on the report, it seems they did an algorithm that can cover all lenses. However, there is absolutely nothing against have specific look-up tables for lenses that don't fit the normal algorithm. So, in theory there is nothing wrong with Canon providing firmware updates to include additional lenses. This could also include a separate set of algorithms for say the current 103 lenses attached to the 1.4x teleconverter. After all, it's just a matter of testing all lenses, teleconverter combinations, and develop the correct algorithms. Then load it into the camera body, provided the memory is large enough to hold all info.

As to third party lenses. In the case of sigma, they work already by pretending to be Canon lenses. At least in Sigma's case with their new lenses and the dock for updates, they might be able to make it work. I.e. first, they have to choose a lens in the the 103 line-up, then they have to check that the algorithm works. If not select another lens. Amongst the 103, hopefully they find one that with some firmware update works.

 

[3kramd5]

If the entire sensor is capable of phase detect, why are there still discrete autofocus points? What keeps them from using a touch screen to say "focus here"?

I believe they demoed exactly that in some of the 70D promo videos.

Cool - haven't seen them.

The phase detect on the sensor only works with the mirror up, and is seamless across the image. With the mirror down, using the viewfinder, you're still using the "old" phase detect system, which still requires the discrete points.

Ah, yes that makes sense. The ability to (auto)focus anywhere on the frame is pretty revolutionary indeed.

Am i the only one who prefers shooting with the optical viewfinder, even if live view is tzhe same speed?

I've never used a system where your "even if" is true, but if one were available I wouldn't mind EVF. I'd rather hold the camera up to my eye than cantilevered in front of my face. In other words, given the "even if," I'd prefer OVF to back mounted LCD in most cases.

 

[unfocused]

Am i the only one who prefers shooting with the optical viewfinder, even if live view is tzhe same speed? I think its not long anymore til Canon only releases only mirrorless cameras if the AF speed is the same. And then people like me can pay another 899$ or whatever for an electronic viewfinder

No, you are not the only one. But, I am increasingly thinking I am more of a dinosaur than I realize (But then again, that happens every time I look in the mirror anyway).

I get that Canon is trying to make live view as useful and accurate as an optical viewfinder, but I hope they don't start to compromise optical viewfinder performance. Sorry, but I just don't see how live view can ever compete with the ergonomics of a viewfinder especially with longer lenses and in bright light.

This seems to me to be another sign of the convergence of video and stills and I suspect that stills photographers are just going to have to learn to accept some compromises as video starts to rule the world.

 

[Joellll]

So let me get this straight....

What the Dual Pixel AF is doing, is that the sensor is actually a two 20mp sensor that is adjacent to each other in a way that it is detecting parallax from the slightest difference between the two pixels?

If that is the case, isn't it actually easier for macro lenses to focus? Since the closer an object is, the parallax effect is more apparent, giving the sensor more difference to detect.