Canon Dual Pixel Liveview Autofocus

[Woody]

The new AF-system is faster, but can´t beat the AF-system of the HG3, G6 and GF6.

Prove this

 

[Bob Howland]

Interesting and promising. Still not as fast as true phase AF, I expect.

Still...I was considering the EOS M, but maybe I'll wait for the EOS M MkII with this technology...

For video, I would not want instantaneous autofocus, since that would provide no transition period. I would, however, want the autofocus to be smooth, with no hunting whatsoever, basically a superb electronic implementation of a highly-skilled focus puller (i.e., first assistant cameraman). (High slew rates provide faster response but are more prone to hunting.)

As for the M MkII, I agree completely, something to replace my G10 but with superb ISO6400 image quality and a decent EVF.

 

[Dylan777]

I'm interested...for video

 

[jasonsim]

Does it have AFMA?

 

[garyknrd]

The movie AF is of interest to me. Will not buy the 70D camera, but if the technology is really that good. Hope they start implementing it in other cameras? I have tried video with the birds I shoot and it is a real pain. This is a great feature. Right up my alley. I really want to get into wildlife videos. Looks like a fun and interesting hobby.
Things are looking up for me with this technology.

 

[weixing]

Hi,
If this dual cmos AF going into their compact camera, it'll be very interesting... ;D

I'm thinking of getting a SX50 to complement my EF 400mm F5.6L for birding, now I think I'll wait for the next model and hopefully, they'll incorporate this into their next generation of ultra zoom camera... hmm... actually, the SX50 pixel is already so small, just wonder can they still maintain usable ISO 800 if split it into 2???

Have a nice day.

 

[traveller]

The proof of this pudding will be the new sensor; if it can catch up with (or surpass) the competition, the 70D will be regarded as a great camera. If this new 20.2MP APS-C sensor is simply a rework of previous designs, the 70D will be seen as just another re-hash of the same old formula Canon, with yet more emphasis placed upon video.

 

[rs]

Interesting development.

For some number of pixels, it is going to reduce (halve?) the amount of light that is received by the photo diode.

If this is the green pixels, as suggested by some diagrams, then it may make little/no overall difference as there are already twice as many green receptors as there are red/blue.

Additionally, this means that there will be some pixels that do not record the same level of light as others. This will need a bit of new fancy footwork for raw converters to properly evaluate what it means to have a pixel that is not and will never have the same luminosity as all of the others around it.

This has potential to have an adverse impact on noise simply due to there being less signal available.

Will be interesting to see the outcome!

Each and every of those 20.2 million active pixels that makes up the picture (whether red, green or blue) is divided into two pixels. One for the left phase, and the other for the right phase. They both hide behind one micro lens, and are positioned next to each other (hopefully without any appreciable gap, as that might cause a strange bokeh effect) to receive the phases. Combined, they theoretically cover pretty much the same area as a conventional photodiode, and should give the same light gathering capability. Its no more than pixel binning to recreate a normal image from this sensor, with normal light gathering capabilities.

So in theory this dual pixel configuration should have no detrimental effects on SNR over a conventional 20.2MP APS-C sensor. Let's hope they've used a new sensor fabrication process to manufacture this sensor, to bring along the much anticipated (and reported) improvements in SNR - I'm guessing that was is in effect a 40.4 MP APS-C sensor would be next to impossible to make with the old sensor fabrication process.

 

[jrista]

According to DPR (http://www.dpreview.com/previews/canon-eos-70d/3), it sounds like PDAF in live view/video recording is possible ANYWHERE in the covered area of the sensor (80% of the central region). That seems pretty impressive...once live view or video AF tracking kicks in, it wouldn't matter where the subject was...there are theoretically no AF points in that mode...the entire sensor is an AF sensor at that point. Sounds like some intriguing new tech to me.

 

[miejoe]

There's a video on the Canon Global website that shows some nice diagrams and explains the process.

http://www.canon.com/news/2013/jul02e.html

Hopefully the added circutry and the inevitable gap from doubling the number of photoreceptors is very small and gives a minimal loss of SNR.

I'm also hoping that the pixels aren't all split in a left/right horizontal pattern, as the video shows, but that half of them are split vertically, because no one would want the AF system to be sensitive to horizontal contrast only.

 

[Loswr]

I'm also hoping that the pixels aren't all split in a left/right horizontal pattern, as the video shows, but that half of them are split vertically, because no one would want the AF system to be sensitive to horizontal contrast only.

Based on what I've read, including a statement from Chuck Westfall who was asked for clarification on the matter, they are all split in the same direction. That means the Dual Pixel CMOS phase AF system is a giant vertical line sensor, responsive only to horizontally-oriented details.

 

[traveller]

I'm also hoping that the pixels aren't all split in a left/right horizontal pattern, as the video shows, but that half of them are split vertically, because no one would want the AF system to be sensitive to horizontal contrast only.

Based on what I've read, including a statement from Chuck Westfall who was asked for clarification on the matter, they are all split in the same direction. That means the Dual Pixel CMOS phase AF system is a giant vertical line sensor, responsive only to horizontally-oriented details.

This will be the 80D's big selling point - "Cross-type Dual Pixel CMOS" ;D

 

[Random Orbits]

I'm also hoping that the pixels aren't all split in a left/right horizontal pattern, as the video shows, but that half of them are split vertically, because no one would want the AF system to be sensitive to horizontal contrast only.

Based on what I've read, including a statement from Chuck Westfall who was asked for clarification on the matter, they are all split in the same direction. That means the Dual Pixel CMOS phase AF system is a giant vertical line sensor, responsive only to horizontally-oriented details.

Any guess as to whether the next generation will have a quad split (2x2) to do both vertical and horizontal or would it be better to use the next neighboring pixel of of the same color instead?

 

[tron]

If they like "playing" with the sensors they might as well make a lower noise/higher DR one : ;D 8)
(Let the debates begin... )

 

[tron]

Or to put it another way, the noise characteristics of the 70D should be about that for a 40MP APS-C sensor using the same sensor technology without the PDAF split.

But then the two parts are combined to one pixel so it isn't it a kind of pixel binning?

 

[BruinBear]

According the Canon the EOS 70D's Dual Pixel CMOS AF system has the following key characteristics:

Usable phase detection AF area covers 80% of the frame horizontally and vertically
AF works at apertures down to F11
AF works in light levels as low as 0 EV
Can work with face detection to keep moving subjects in focus

 

[alan_k]

This is from the DP-Review hands-on Preview (bold mine)

According the Canon the EOS 70D's Dual Pixel CMOS AF system has the following key characteristics:

Usable phase detection AF area covers 80% of the frame horizontally and vertically
AF works at apertures down to F11
AF works in light levels as low as 0 EV
Can work with face detection to keep moving subjects in focus

Does this mean, for example, I could get AF on a 70-300L + 2xTC, and if so, only in live-view?

e: you read my mind!!!

 

[Loswr]

This is from the DP-Review hands-on Preview (bold mine)

According the Canon the EOS 70D's Dual Pixel CMOS AF system has the following key characteristics:

Usable phase detection AF area covers 80% of the frame horizontally and vertically
AF works at apertures down to F11
AF works in light levels as low as 0 EV
Can work with face detection to keep moving subjects in focus

Does this mean, for example, I could get AF on a 70-300L + 2xTC, and if so, only in live-view?

e: you read my mind!!!

Sure...but you could do that with Live View on any camera (although not with phase detect AF).

 

[Mt Spokane Photography]

I'm also hoping that the pixels aren't all split in a left/right horizontal pattern, as the video shows, but that half of them are split vertically, because no one would want the AF system to be sensitive to horizontal contrast only.

Based on what I've read, including a statement from Chuck Westfall who was asked for clarification on the matter, they are all split in the same direction. That means the Dual Pixel CMOS phase AF system is a giant vertical line sensor, responsive only to horizontally-oriented details.

That's also what I surmised from Canon's video. However, I believe that in Portrait mode, the sensor would be only seeing vertical details unless the camera is able to switch between the two automatically, which doesn't seem likely - at least not in a mid range model.

I am wondering about things like banding, or a new type of artifact that might appear due to the divided photo sensors. That's pretty dependent on the actual fine details of how it works, something that we are not going to get from Canon.

As to patents, the sensor sounds like it uses this recent patent from Canon.

http://translate.google.com/translate?twu=1?sl=auto&tl=en&u=http%3A//egami.blog.so-net.ne.jp/2012-08-12

After reading the patent document, I found it to be very complex, but it is almost certainly what we are seeing.

The wording is very engineering like, and looks like something intended for a mirrorless camera, which is why it was not anticipated to appear in a DSLR first.

While AF is said to be 30% faster, its obviously not yet going to beat conventional phase detect AF for speed. However, with more computing horsepower as might happen with a dual Digic 5+ processor or a newer version of Digic, we might see the mirror go away for good.

 

[@!ex]

Here is another video showing what the focus pulls look like when you use the touchscreen to focus while you are shooting in live view. It actually looks pretty nice. They also have some examples of auto focus ect. if you watch after the credits in the middle of the video they replay the video with an overlay showing focus info and some metadata.

https://www.youtube.com/watch?v=Tf0BBNr6Epk&feature=player_embedded