[falconeye]

Currently I guess that the AF base equivalent of Canon's MPAF may not be that large because the photodiodes are probably not that discriminating in terms of angular sensitivity. However, this will probably be addressed when MPAF uses 16 photodiodes, or so, in place of one conventional sensel.

Over at DPR, somebody now pointed me at a second Canon patent originally filed Dec 2011 in Japan but available as US patent. It treats the algorithmic problems and how to switch between contrast maximization and phase minimization. They call it sum or difference signal. It is a rather simplistic view at the problem. If Canon really does it that way, they are not exploiting their own invention's potential. A better approach would be to combine both approaches and to use (2D auto- and cross-) correlation functions rather than (1D) summation and difference filters. And to drive the sensor in varying modes (sparse, windowed etc.) to obtain an optimum signal at max. speed for a given phase within the still photo AF operation (target selection, focus, precision focus, stopped-down focus).

This is the patent: http://patentimages.storage.googleapis.com/pdfs/US20130147998.pdf

BTW, it doesn't seem to quote the original JP patent I found in the Japanese web. So, Canon did not file it in the US. Rather interesting. Maybe, they didn't want to make it too obvious what it is based upon.

Yes, Fuji's idea (as used by Hybrid-AF and MPAF) has a low angular sensitivity (although it can be large with fast lenses -- Canon in the patent even speaks of problems in this case to determine shift between then differently shaped signals, another hint at a simplistic approach). The low angular sensitivity can be offset by a high precision correlation function between the partial images which turns even small differences into a solid signal. My multi pixel idea (quad pixel) does not increase the angular sensitivity. But it solves the ambiguity problem where the cross correlation maximization has no clear single solution (either because of missing texture or too large a parallax error). It is the cross type AF sensor analog. More than 4 pixels most probably won't help, although it could at least in the case of very wide apertures.

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Last edited by falconeye; 07-05-2013 at 02:26 AM.

[falconeye]

I've attached a machine translation of the patent, for what it is worth. (apparently this site does not support uploading RTF files, so I made it a DOC).

Thanks.

(you could have used PDF). As the drawings have been "lost in translation", here is the link to the Japanese PDF:
-> http://nawaphotography.web.fc2.com/etc00/JPA_2012037777.pdf

Btw, the patent described to only split every 2nd green into two halves (this would have increased the pixel count from 20MP to 25MP only, but only using 1/4 of light for AF). And to create three groups, where the split is in the middle, or more geared towards one or the other side. Which would create 3 signals of differing phase shifts helping in eliminating ambiguities. Which is a good idea.

However, it does not describe of having e.g., two groups, where the split is either horozontal or vertical. Which would have been even better at resolving possible ambiguities. Another sign the patent was rushed to filing.

The later patent only describes all pixels all split equally.

[Clavius]

So it has come to this: A mid-grade beats the Pentax "flagship" K-5IIs with ease... That hurts.

[sarcasm]
Quick Pentax PRIC Ricoh, market the K-5IIs in all possible colours before it's to late!
[/sarcasm]

Who would have thought that we would wish Hoya back?

[JinDesu]

Er? I always thought the 60D was the competitor to the k-5? They are both the same class of cameras. And so far it only "beats" the k-5IIs in AF (but not low-light AF, unless the 7D's AF was good to -3EV too) and in touchscreen LCD. I have not seen anything about the new 20MP sensor, so can't comment on that. Otherwise - everything else is practically equal (excepting Canon's natural advantages such as flash support, etc).

[JPT]

falconeye - Thanks for all the insight in this thread. I'll probably buy a new camera in a couple of years and it makes me excited about what it will be capable of.

[Clavius]

Er? I always thought the 60D was the competitor to the k-5? They are both the same class of cameras.

Canon can't help it that Pentax is sitting still. The 70D is the replacement of the 60D:

The EOS 70D is a mid-range SLR for enthusiast photographers that from the outside looks like a sensible, indeed desirable upgrade to the EOS 60D.

So, it's a Canon mid range SLR that beats the Pentax flagship SLR.

And so far it only "beats" the k-5IIs in AF (but not low-light AF, unless the 7D's AF was good to -3EV too) and in touchscreen LCD. I have not seen anything about the new 20MP sensor, so can't comment on that. Otherwise - everything else is practically equal (excepting Canon's natural advantages such as flash support, etc).

Equal? Excuse me?

- Autofocus from the 7D.
- Fully articulating touchscreen.
- Built in wifi.
- 20.2 MP
- Phase detection in live view.
- Phase detection during movie mode.
- And so on...

... And at that price!

[JinDesu]

Canon can't help it that Pentax is sitting still. The 70D is the replacement of the 60D:


So, it's a Canon mid range SLR that beats the Pentax flagship SLR.





Equal? Excuse me?

- Autofocus from the 7D.
- Fully articulating touchscreen.
- Built in wifi.
- 20.2 MP
- Phase detection in live view.
- Phase detection during movie mode.
- And so on...

... And at that price!

I conceded the touchscreen and standard AF. The only problem I had with your post is the "with ease". I understand that the k-5II/s is a stopgap camera and shows that Pentax is currently standing still. However, it is still a fantastic camera that stands practically toe-to-toe with the new D7100 and the newly announced D70 - especially with the IBIS and the proven 16MP sensor with great DR and noise control. Until I learn more about the 20MP sensor of Canon, I would not say it trounces the k-5II.

[JPT]

So, it's a Canon mid range SLR that beats the Pentax flagship SLR.

Even assuming that the IQ is now as good as the K-5 II, it's a camera announced 10 months after the K-5 II and probably only a few months ahead of it's replacement. It would be surprising if the 70D didn't perform better in some ways.

[Aegon]

The 70D is a step on the path toward next decade's camera. The K-5 IIs walks the path of the current decade's cameras. However good the K-5 IIs may be it does not inform the industry as to where the future of photography lies.

The consequences of the 70D (as well as the patent for the focusing techniques used by the 70D) will be far-reaching. The 70D shows that Canon has the potential to trounce the industry for the next decade.

As an example, Nikon's focusing system from the CX series of cameras had previously been limited to the red-headed stepchild CX series of cameras and lenses. Now Nikon *must* respond with on-sensor PDAF for their competitor to the 70D, which is an area they have been reluctant to explore. (As a side note, I believe their reluctance was based on market segregation rather than usefulness).

Furthermore, Nikon's approach may be just fine for hobbyists, and may compete well enough with the 70D. But 5 years from now the successors to Canon's 70D will be optimized and massaged into supreme autofocus machines, probably surpassing the PDAF of today's pro bodies. These cameras will have fewer moving parts and therefore be cheaper to manufacture. And the technology should trickle down into the whole lineup of bodies.

Meanwhile, Pentax may finally work out the details of PDAF, implementing more expensive solutions and providing features of current Canon/Nikon AF systems. I don't consider this to be a good position for Pentax.

[Samsungian]

Thesedays the Canon 60D sells for $599 in USA


Canon EOS 60D DSLR Camera (Body Only) 4460B003 B&H Photo Video

while Pentax K-5 remains at $996

Pentax K-5 II Digital SLR Camera 12016 B&H Photo Video

a $400 difference.

70D intrigues me even though I've given up on buying another aps-c sensor camera from anyone.

If Canon offered full frame with articulated viewscreen I'd sell off all my real Pentax Made in Japan gear to buy two Canon FF Dslrs & with remaining cash in hand leftover I'd buy more eos gear. Maybe 17mm TSE or 24mm TSE ??

If Nikon made an articulated viewscreen full frame dslr I'd sell off Pentax treasures and buy two from Nikon and have cash to spare to buy someting else...

Instead I watch as Ricoh after two years wrestles with renaming Pentax "Ricoh" & what 100 colors sell better than the other 100+ colors in 2013-14.

Er? I always thought the 60D was the competitor to the k-5? They are both the same class of cameras. And so far it only "beats" the k-5IIs in AF (but not low-light AF, unless the 7D's AF was good to -3EV too) and in touchscreen LCD. I have not seen anything about the new 20MP sensor, so can't comment on that. Otherwise - everything else is practically equal (excepting Canon's natural advantages such as flash support, etc).

[JinDesu]

Thesedays the Canon 60D sells for $599 in USA


Canon EOS 60D DSLR Camera (Body Only) 4460B003 B&H Photo Video

while Pentax K-5 remains at $996

Pentax K-5 II Digital SLR Camera 12016 B&H Photo Video

a $400 difference.

70D intrigues me even though I've given up on buying another aps-c sensor camera from anyone.

If Canon offered full frame with articulated viewscreen I'd sell off all my real Pentax Made in Japan gear to buy two Canon FF Dslrs & with remaining cash in hand leftover I'd buy more eos gear. Maybe 17mm TSE or 24mm TSE ??

If Nikon made an articulated viewscreen full frame dslr I'd sell off Pentax treasures and buy two from Nikon and have cash to spare to buy someting else...

Instead I watch as Ricoh after two years wrestles with renaming Pentax "Ricoh" & what 100 colors sell better than the other 100+ colors in 2013-14.

https://www.pentaxforums.com/forums/pentax-price-watch/226860-k-5-18-55-fs-725-buydig.html

https://www.pentaxforums.com/forums/pentax-price-watch/229902-k-5-699-shipped-adorama.html

https://www.pentaxforums.com/forums/pentax-price-watch/228411-k-5-original-6...-w-coupon.html

?? $100 more maybe, not $400 more.

[Samsungian]

I only shop at B&H period

Nice to see the K-5 is dropping in price elsewheres.
Why Pentax refuses to share the love with B&H is a mystery to me.


No doubt more Pentax logo'd gear is sold thru B&H in USA than anywhere else & I won't buy from anyone else, so no new "Pentax" goodies to taunt me. Best price via other vendors is another reason keep my money in my wallet.

No biggie, no great deals on K-5 at B&H on Pentax gear leaves me with cash in my pocket. I'm kinda put off with everyone thesedays, the epic 25% yen depreciation vs dollar gets me no traction. Same prices since 2011, whats up with that ? I use what I own & buy nothing more from any imaging company in the meantime...
...well till Turkey Day,
I have high expectations I'll see major price drops in Canon~Nikon.

No clue about what Pentax plans are except the easy guess:

More color decorating, more of the same without ANY full frame k mount option, as usual...

https://www.pentaxforums.com/forums/pentax-price-watch/226860-k-5-18-55-fs-725-buydig.html

https://www.pentaxforums.com/forums/pentax-price-watch/229902-k-5-699-shipped-adorama.html

https://www.pentaxforums.com/forums/pentax-price-watch/228411-k-5-original-6...-w-coupon.html

?? $100 more maybe, not $400 more.

[johnmflores]

"Canon claims the new Dual Pixel CMOS AF system is 30% quicker than its previous hybrid AF implementation"

What is the previous hybrid AF system that they are benchmarking themselves against? For their sake I hope it's not the EOS-M.

[Fogel70]

So it has come to this: A mid-grade beats the Pentax "flagship" K-5IIs with ease... That hurts.

[sarcasm]
Quick Pentax PRIC Ricoh, market the K-5IIs in all possible colours before it's to late!
[/sarcasm]

Who would have thought that we would wish Hoya back?

Does it also hurt that Pentax entry level K-500 beat Canon 70D in some ways.

K500 has
Larger sensor
Larger pentaxprism OVF with 100% coverage
Most likely better IQ at high ISO.
Image stabilization on all lenses
...

[falconeye]

"Canon claims the new Dual Pixel CMOS AF system is 30% quicker than its previous hybrid AF implementation"

What is the previous hybrid AF system that they are benchmarking themselves against? For their sake I hope it's not the EOS-M.

Good question. I took it as sign that the 70D incarnation of Multi Pixel AF isn't all that great. However, I don't care as it doesn't compromise the technologies' huge potential.

As for the 70D, Canon only advertizes it as a break-thru for movie and I am sure they know why