Patent: How Canon Increased AF Point Spread in the EOS 5D Mark IV

[Canon Rumors Guy]

<a href="http://www.northlight-images.co.uk/cameras/Canon_rumours.html">Northlight</a> has broken down a patent that shows how Canon was able to increase the spread of the AF points in the EOS 5D Mark IV.</p>
<blockquote><p>A Canon patent shows how by replacing the sub mirrors with laminated diffraction gratings, the normal angle of relflection can be altered, adding or subtracting to the usual angle. In the example of the 5Dmk4 this is used to expand the vertical coverage of the AF sensor array.</p></blockquote>
<p><a href="http://www.canonrumors.com/wp-content/uploads/2016/08/5d4-supermirror.png"><img class="aligncenter size-medium wp-image-26632" src="http://www.canonrumors.com/wp-content/uploads/2016/08/5d4-supermirror-593x575.png" alt="5d4-supermirror" width="593" height="575" srcset="http://www.canonrumors.com/wp-content/uploads/2016/08/5d4-supermirror-593x575.png 593w, http://www.canonrumors.com/wp-content/uploads/2016/08/5d4-supermirror-610x591.png 610w, http://www.canonrumors.com/wp-content/uploads/2016/08/5d4-supermirror.png 708w" sizes="(max-width: 593px) 100vw, 593px" /></a></p>
<p>As with a lot of Canon DSLRs, there are subtle advancements that will make using the tool better. Increased AF point spread is something a lot of photographers have wished for, and I think a lot of photographers will welcome once they have it.</p>
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[LordofTackle]

So is this probably the same technique used in the 1DX II? Since it also has a vertically expanded AF area.
Or did they do something else with the 1DX II?

Edit:
Since the increase in the spread of AF points is the same for both cameras (8% more in the center field, 24% more in the side fields), it's most likely the same technique.

 

[sulla]

OK, in case you do not want to develop a new, bigger AF sensor, it might be just cheaper to develop a diffraction secondary mirror.
I however wonder why they haven't simply used a curved secondary mirror?

 

[[email protected]]

Quote: "I however wonder why they haven't simply used a curved secondary mirror?"

Likely because the curve at the focus point would give a range of distances, rather than a simple focal plane distance. It would make things fudgy. This grating solution is pretty clever.

 

[Sator]

Egami states very clearly that while there seems to be a lot of new technology in the 5DIV, he cannot tell whether the patent under discussion here was implemented on the 5DIV. I quote:

EOS 5D Mark IVでは測距エリアが垂直方向に広げられています。 この特許がEOS 5D Mark IVで使われたのか分かりませんが、EOS 5D Mark IVには数多くの新技術が投入されているようですね。

It is thus simply incorrect to state unconditionally that this was "How Canon Increased AF Point Spread in the EOS 5D Mark IV".

I suspect this is based on a misunderstanding of the Egami's commentary. I talked more about that here:

https://plus.google.com/u/0/116458677975033889029/posts/Xxtr5QAW3jZ

 

[Maiaibing]

OK - I'll take any expansion - but that's not the most impressive "expansion" one could imagine... ???

 

[TWI by Dustin Abbott]

I shared my first video on the 5D MKIV (https://www.youtube.com/watch?v=p_sqG76FBlU) and why I'm preordering and got a surprising amount of angry responses. Lots of "2012 technology" responses, etc... That wasn't the initial reaction, but there seem to be some bloggers and reviewers that have really come out negatively. People are also upset by the price (in non US markets), obviously.

Here's the thing, though. It is the little things like this (expanded AF point coverage) that will make the camera better than the specs suggest. There's one thing that I admire Canon for, and that is that they tend to deliver mature tech that is fully executed as opposed to others (Sony is one example) who have magnificent spec lists but sometimes poor concept execution.

 

[[email protected]]

Dustin, I think you're right, but people often think this is merely rationalizing inadequate advancement because they don't have a feel for the cumulative feel a bunch of these small upgrades actually bestows on the camera.

Here is how I know: I shot the 7D2 for a year before I got a 5D3. The 5D3 was a superior camera in most ways due to the full frame sensor, but there were at least a dozen things about the 7D2 that were upgraded because it came out a couple years later. The lack of those things frustrated the heck out of me whenever I used the 5D3. I completely favored using the 7D2 as a result.

Things like a much better shutter sound and feel; anti-flicker; the thumb control; wider af points (albeit partly due to crop nature of sensor); intervalometer; and etc... made the camera a real favorite. This despited the fact that any one of those factors could have been taken out, and I would have shrugged without thinking it terribly significant.

The *FEEL* of the camera with these improvements is something that you're not going to be able to easily convey to your audience, and they will complain at you vociferously until they too have a chance to shoot the 5D4.





Dustin quote:
"I shared my first video on the 5D MKIV (https://www.youtube.com/watch?v=p_sqG76FBlU) and why I'm preordering and got a surprising amount of angry responses. Lots of "2012 technology" responses, etc... That wasn't the initial reaction, but there seem to be some bloggers and reviewers that have really come out negatively. People are also upset by the price (in non US markets), obviously.

Here's the thing, though. It is the little things like this (expanded AF point coverage) that will make the camera better than the specs suggest. There's one thing that I admire Canon for, and that is that they tend to deliver mature tech that is fully executed as opposed to others (Sony is one example) who have magnificent spec lists but sometimes poor concept execution."

 

[Sator]

I shared my first video on the 5D MKIV (https://www.youtube.com/watch?v=p_sqG76FBlU) and why I'm preordering and got a surprising amount of angry responses. Lots of "2012 technology" responses, etc... That wasn't the initial reaction, but there seem to be some bloggers and reviewers that have really come out negatively. People are also upset by the price (in non US markets), obviously.

Here's the thing, though. It is the little things like this (expanded AF point coverage) that will make the camera better than the specs suggest. There's one thing that I admire Canon for, and that is that they tend to deliver mature tech that is fully executed as opposed to others (Sony is one example) who have magnificent spec lists but sometimes poor concept execution.

I totally agree with this. One Japanese site mentioned that the IQ of the 5DIV rivals that of the 5DsR. The reason is that IQ isn't just about megapixels, but Canon also upgrades a whole lot of other algorithms at the same time.
Unfortunately people hate sobriety, and prefer bloated spec delirium, however poorly implemented, because it gives them more bragging rights.

As for pricing, that is largely due to Brexit pushing up the Yen vs other currencies like the Canadian and Australian dollar which are both collapsing due to a drop in iron ore and mineral export pricing driven by a slump in Chinese demand. Not Canon's fault at all (unless you think Canon singularly manipulates the entire world economy).

However, once again we do not yet have evidence that Canon have implemented this particular sub-mirror patent in the 5DIV.

 

[GMCPhotographics]

OK, in case you do not want to develop a new, bigger AF sensor, it might be just cheaper to develop a diffraction secondary mirror.
I however wonder why they haven't simply used a curved secondary mirror?

I'm sure if the science was that easy, Canon would have done that years ago.

 

[ashmadux]

What would it take to spread the points beyond the middle?

This tiny amount of re-positioning will have a very minute effect, imho. I tend to waste sooooo much pixels because im trying to hit the top left or tight third in (either orientation). for medium telephoto lenses, its a S___eshow.

 

[sulla]

I doubt the physics behind a curved mirror is too difficult.
Also, they could probably have used an anamorphic lens in the focussing unit of the AF system, I guess.
But a diffraction grating on the secondary mirror is way cooler and probably cheaper to manufacture.

 

[M_S]

I shared my first video on the 5D MKIV (https://www.youtube.com/watch?v=p_sqG76FBlU) and why I'm preordering and got a surprising amount of angry responses. Lots of "2012 technology" responses, etc... That wasn't the initial reaction, but there seem to be some bloggers and reviewers that have really come out negatively. People are also upset by the price (in non US markets), obviously.

Here's the thing, though. It is the little things like this (expanded AF point coverage) that will make the camera better than the specs suggest. There's one thing that I admire Canon for, and that is that they tend to deliver mature tech that is fully executed as opposed to others (Sony is one example) who have magnificent spec lists but sometimes poor concept execution.

Perhaps the crowd has a voice too and not all is praise and glory with this camera. Looking at the some technical aspects it can't be denied that its old on arrival in certain aspects. Especially on the video front.
Old HDMI-port v 1.3, old storage standards, especially the UHS I is way too much for my taste, old and inefficient codecs for video, buffer not as big as others and the list goes on. Dustin I like your reviews, but sometimes they tend to be too positive when there are things that stick out and say "why on earth, now, really". Mature tech could easily translated to gold old trusted. This however comes short of outdated, missing some innovation, not the technical leader, playing it safe. This is a camera they are releasing today to compete with the best on the market...for another 4 years. Lets put that into perspective and compare it to existing gear.
* The old D800 surpases the MP count, the D820 will be around he corner, at least in the 4 year cycle. Put some form of D5-AF system (3D) in there, put the speed up a but and you have a very fine body, besting the Mark 4 in some key areas in stills photography
* The A7R2 has already a whopping 42MP and does 4K from the whole sensor (giving it that full frame look), putting the signal out over the HDMI. The newly released 5dIV can't do that at all, because of old tech limitations and has a chuge crop (1,74x) . How embarassing is that? Since you are stuck with the lenses you have to adjust accordingly but you will never get that full frame look you hoped to get in the first place. Speedboster won't work, so there goes nothing.
* GH4 can do a compressed codec. MK4 uses the Motion jpg codec wih huge file sizes you have to convert to work with in post.
* Log picture style is missing as well. Sony and other major companies are putting it in to give you better options in post.
So all is not limitations here, it is clearly possible to implement it in a camera body, but Canon plays safe and puts old tech in there or leaves things deliberately out the competition is alreay implementing.
How does the Wifi-connection work? Tony Northrup made some statements about this and it doesn't sound very intuitive to me. If true, Wifi looks better on the spec sheet than in real use. But that is better left oit for the final reviews.
I am not saying that the other competitors do it with waving flags. The Sony menu system is a pain, the battery life is a joke, Nikons system speed is not to my liking. Thats why I sticked with Canon and bought into the system. But thats about it. I like the convenience factor. But when I see, what other manufacturers can offer, I look twice now if the convenience is the most important thing or if there are aspects, where in my opnion, Canon is lacking features I really would have to in my arsenal. Usable 4K would have been key to me, future proof saving system and interfaces as well and no AA Filter for sharper pics (like in the Nikons)...I simply can't understand why they even bothered to put 4K in, the way they did it, why even market it?

 

[cazza132]

All I have been hearing is people whinging and bitching about Canon's apparent lack of innovation (probably people paid to do so).
Last time I checked, Canon came up with:
- anti-flicker
- BD optics and
- more importantly, dual pixel tech.
Diffraction grating to improve effectiveness of AF spread - now that is pretty cool! And people still bitch?
In the 5DIV, it will be interesting to see if the dual pixel tech will (by default) increase DR if readout to file is indeed 60MP to 30MP (SQRT 2 read noise) and not just the newly standard on board ADC. We saw DR increase with pixel density alone with the 5Ds.
Yes, it is a bitch here in Australia atm. Exchange rate is down, so consumer imports cost way more - exactly as Sator pointed out The 5D Mark III was released when the Australian Dollar was on parity or more than the US Dollar - people need to remember that.
One thing that I am confident with, it that the 5D Mark IV will be a rockin' cam!

 

[Ozarker]

My old man told me, before he left this world, the right camera can make ya, and the wrong camera can break ya.

Proud to be a Canon man.

 

[Ozarker]

All I have been hearing is people whinging and bitching about Canon's apparent lack of innovation (probably people paid to do so).
Last time I checked, Canon came up with:
- anti-flicker
- BD optics and
- more importantly, dual pixel tech.
Diffraction grating to improve effectiveness of AF spread - now that is pretty cool! And people still bitch?
In the 5DIV, it will be interesting to see if the dual pixel tech will (by default) increase DR if readout to file is indeed 60MP to 30MP (SQRT 2 read noise) and not just the newly standard on board ADC. We saw DR increase with pixel density alone with the 5Ds.
Yes, it is a bitch here in Australia atm. Exchange rate is down, so consumer imports cost way more - exactly as Sator pointed out The 5D Mark III was released when the Australian Dollar was on parity or more than the US Dollar - people need to remember that.
One thing that I am confident with, it that the 5D Mark IV will be a rockin' cam!

 

[cazza132]

Perhaps the crowd has a voice too and not all is praise and glory with this camera. Looking at the some technical aspects it can't be denied that its old on arrival in certain aspects. Old HDMI-port v 1.3, old storage standards, especially the UHS I is way too much for my taste, old and inefficient codecs for video, buffer not as big as others and the list goes on. Dustin I like your reviews, but sometimes they tend to be too positive when there are things that stick out and say "why on earth, now, really". Mature tech could easily translated to gold old trusted. This however comes short of outdated, missing some innovation, not the technical leader, playing it safe. This is a camera they are releasing today to compete with the best on the market...for another 4 years. Lets put that into perspective and compare it to existing gear.

That's a pretty big whinge dude. A very video-istic point of view. I don't think video people would mind the dual pixel AF servo offered in no other brand on the market. An alternate codec could be implemented via firmware (Magic Lantern or Canon down the track if the 5DII is anything to go by) Can you pull 8.8MP stills from highly compressed Sony or any other video? Given enough RAM and a decent CPU, a decent computer can manage Canon's vid output.

The old D800 surpases the MP count, the D820 will be around he corner not to long I guess.
If you want MP - the 5DsR is the king.

Put the AF system (3D) of the D5 in there and you have a very fine body, very likeliy outperforming the Mark IV in every aspect.
No proof - AF performance D5 vs 1DXII is similar and reviews depend on reviewer. D5 for low light and IDXII for all other is the general consensus. Many comparisons haven't exploited the 1DXII's ability to be customized. The same applies to the 5DIV. The 5DIV has added AF servo to dual pixel live view for stills, which is unique.

The A7R2 has already a whopping 42MP and does 4K over the whole sensor
With loads of jello and inferior performance to its native heavily cropped alternative.

The newly released 5dIV can't do that because of old tech limitations and has a chuge crop. How embarassing is that? I am not saying that the other competitors do it with waving flags.
I have had girlfriends that whinge like that about a new microwave oven. Lucky I do most of the cooking

Usable 4K would have been key to me, future proof saving system and interfaces as well and no AA Filter for sharper pics (like in the Nikons)..
A lack of AA filter below 36 MP is questionable at best for an all round camera. What are you thinking? The choice of having and AA filter is wise for a cam like this that would be used by many wedding togs.
Sounds like you need a Sony A7s for video and what ever alternative you like for photos.

 

[cazza132]

All I have been hearing is people whinging and bitching about Canon's apparent lack of innovation (probably people paid to do so).
Last time I checked, Canon came up with:
- anti-flicker
- BD optics and
- more importantly, dual pixel tech.
Diffraction grating to improve effectiveness of AF spread - now that is pretty cool! And people still bitch?
In the 5DIV, it will be interesting to see if the dual pixel tech will (by default) increase DR if readout to file is indeed 60MP to 30MP (SQRT 2 read noise) and not just the newly standard on board ADC. We saw DR increase with pixel density alone with the 5Ds.
Yes, it is a bitch here in Australia atm. Exchange rate is down, so consumer imports cost way more - exactly as Sator pointed out The 5D Mark III was released when the Australian Dollar was on parity or more than the US Dollar - people need to remember that.
One thing that I am confident with, it that the 5D Mark IV will be a rockin' cam!

Hahaha! Yep

 

[cazza132]

I can't see the 'front page' worthiness of this feature. "Here's how Canon increased the vertical AF Point spread by a couple millimeters" .... ???

This was one of the things mentioned by the Canon 'Explorers of Light' in the B&H video as well. Prior to that video this was not a feature on my radar. The B&H video made me look for the change specs ... the change specs documented on CR then made me LOL.

https://youtu.be/l-57O3cpzPs?t=3019

Image diagonal is only 21.6mm radius. A few mm becomes quite a bit!

 

[SPL]

I shared my first video on the 5D MKIV (https://www.youtube.com/watch?v=p_sqG76FBlU) and why I'm preordering and got a surprising amount of angry responses. Lots of "2012 technology" responses, etc... That wasn't the initial reaction, but there seem to be some bloggers and reviewers that have really come out negatively. People are also upset by the price (in non US markets), obviously.

Here's the thing, though. It is the little things like this (expanded AF point coverage) that will make the camera better than the specs suggest. There's one thing that I admire Canon for, and that is that they tend to deliver mature tech that is fully executed as opposed to others (Sony is one example) who have magnificent spec lists but sometimes poor concept execution.

+1