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Messages - x-vision

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16
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 21, 2014, 01:14:42 PM »
I'm no electrical engineer with a Ph.D ...

Yup, that was pretty obvious ... and I was right about that (so, I was definitely right at least about one thing  8) ).

Kudos for having the courage to admit it, though. Seriously.

Of course now all the people on your side of this argument should have second thoughts on
why they should be listening to you.

And btw, I happen to be an electrical engineering by training. Not a Ph.D., though.

17
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 21, 2014, 01:03:29 PM »
I don't really have the heart to continue the conversation, because the clueless one here is not me...
Here we go. Resorting to personal attacks and bullying again.

Admit it, you don't have a technical background.
That's why you run in circles, contradicting yourself, when you try to explain a technical concept.

You are the clueless one, not understanding the basic underlying principles.
I pointed out the flaws in your arguments about pixels vs photodiodes - but you are clueless to understand it.

Let's leave it at that.

18
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 21, 2014, 12:16:05 PM »
Your claim of a quad-pixel design is based on a flawed assumption you're making after totally misinterpreting a single piece of data (a picture of a part of the sensor that's not the active imaging area). 

My claim is not based solely on that.

I now admit, though, that the partial picture of the sensor die from Chipworks is not sufficient/reliable evidence to support any claims.
Therefore, I'm officially retracting it as evidence. I was wrong to quote it and I won't do it again.

Quote
The claim of a dual-pixel design is not based on assumptions, it's based on actual published patents issued to Canon for the technology.  That's established fact vs. ill-informed speculation. 

Of all those published patents, so far we've only seen a link to a schematic diagram of the 'dual-pixel' tech.
That's all. Everything else has been based on Canon's officially published information.

I'm not claiming that Canon's information is incorrect (hell, no). All I'm saying is that it's not guaranteed to be 100% revealing.

I asked for a link to the all-important patent that shows rectangular photodiodes.
As I said in a previous post, this patent would settle the discussion - but Jrista hasn't provided it.

Btw, this is the CanonRumors site.
By definition, most of the info published on the front page of this site is ... ill-informed speculation.
If you have such high standards for fact vs fiction, how come you are a regular on this forum ??
If you were holding CanonRumors accountable for the info that they are publishing, they should have closed shop by now.
???

Quote
If you want your claim to be in any way believable, you need actual evidence.  Read the Canon patents on dual-pixel AF - show us where a quad pixel design is mentioned.  Show us a verifiable image of the actual photodiodes of the 70D sensor (not the dead area at the very edge of the sensor in the Chipworks teaser). 

Fair enough.

I've never presented my speculations as facts. 
But if one day I decide to do that, I'll make sure that I have very solid evidence.

19
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 21, 2014, 04:35:56 AM »
Therefor, you cannot share the readout transistors, because both are read out simultaneously. Therefor, DPAF does NOT use a shared pixel design. There is, literally, two independent sets of transistors to read out each half of the pixel when the row is activated...and twice as many columns.

In other words, the two halves are read as ... independent pixels.
I feel that we are getting somewhere.
Oh, wait! That's what I've been saying all along.

The shared-transistor part is a different story.
I've never said explicitly which transistors are shared - and that's the key here.

20
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 21, 2014, 04:23:08 AM »
As for the rest, your making a LOT of assumptions, and piling assumption on top of assumption, then making bold claims about how you've discovered Canon has QPAF technology ...

Whenever I said anything on the topic, I've always started with 'by the look of things...', 'theoretically...', etc..
And I've been usually finishing my posts with 'it's all speculation', 'it's fun to speculate', or something like that.
I wouldn't say that I've been making bold claims. Mostly speculation and fun 8).

21
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 21, 2014, 04:14:55 AM »
That is the exact OPPOSITE of a shared pixel. Shared pixels SHARE readouts. Canon's DPAF use INDEPENDENT readouts.

Heh. You share readout circuitry between photodiodes ... to read their output independently.
What a paradox. And yet, that's exactly what the industry has been doing for a decade now (or more?).
Fascinating stuff. LOL.

22
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 21, 2014, 03:05:30 AM »
I know EXACTLY what I am talking about ...

Hmm. Doesn't look like it. Let's see.

First you say this:

Quote
The photodiode is the light-sensitive part of a pixel. A standard bayer pixel is comprised of a photodiode, at least one microlens layer (sometimes two), and a color filter, as well as the row/column activate wiring, amplifier, and readout transistors.

And then you say:

Quote
In a DPAF pixel, the photodiode has been split in half, with insulating material between the two halves. Each halve has independent readout.

So, a pixel has a photodiode and readout transistors (in addition to the other stuff).
Simialrly, a DPAF pixel is a (half) photodiode ... with an independent readout.

Do you even realize that by splitting the photodiode in two, and by providing independent readouts for each half,
you have essentially created two pixels ?

I don't think you do!
That's why you can't grasp that a split photodiode is in fact a separate pixel - etched on the silicon wafer.

The microlenses and color filters are secondary - put on top of the already etched wafer.
You can put a microlense and a color filter on top of multiple pixels.
That's what Canon is doing - and what you call a pixel with a 'split photodiode'.
What you don't grasp, obviously, is that a split photodiode with independent readouts ... is two separate pixels.

Quote
The photodiode, despite being split, still exists below the color filter and microlenses. Therefor, there is still ONE pixel...with two photodiodes.

There you go. That's the part that is escaping you.
It's ONE pixel in the image, not on the silicon wafer.

There is a reason I mentioned the 'classic' 3T pixel and the shared transistor designs.
And that is to illustrate the point that a 'pixel' can be implemented in different ways.
The important distinction is that the wafer is etched in a way so that you can read photodiode charges independently.

That's what a pixel is on the wafer level.
You can certainly combine the output of multiple pixels into one.
Or put a single microlens on top of multiple pixels.
But as long as you have a photodiode and independent readout circuitry, regardless of configuration,
you have a pixel - and that part is definitely escaping you.

And the reason is that you are not technical enough to grasp the underlying principle here.
So, no, you don't know what you are talking about.

Quote
You misunderstand shared-pixel designs. Shared pixels do not share the photodiode. Each pixel still has it's own independent photodiode.

You mean just like a split photodiode with two independent readouts???


Quote
The photodiodes ARE rectangular! That's EXACTLY what they are! That's exactly how they are described in Canon's patents on the technology!  ::)

O-o-kay. Care to share a link to least one of these patents. That should settle it, right?
So, let's settle it by you providing a link to at least one of these patents.
You have the link handy, don't you?

Look, I suggest that you drop the 'I'm the authority' attitude - because you are not an authority.
In fact, it's very clear that you don't even come from a technical background.
So, drop the attitude and let's have a friendly discussion.
That's the reason why we are all here, no?. What's with all that bullying ??

23
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 21, 2014, 01:48:51 AM »
Magic 8-Ball says "All signs point to 2 photodiodes." 
Fair enough.

Quote
You still might be right, but the bulk of evidence is against you.

Heh. All the evidence is coming from one source - Canon.
If it corroborated by at least one other source, I maybe wouldn't have argued.
But for now we either accept what Canon is saying ... or not  8).

24
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 21, 2014, 12:53:04 AM »
... but it's based on published material. 

Right. But that's still marketing materials.

25
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 21, 2014, 12:18:29 AM »
No, that is fundamentally incorrect. You start with a 20mp sensor, which has 40mp PHOTODIODES.


Jrista, you are just assuming that Canon's dual-pixel tech is in fact a dual-photodiode tech.
My assumption is that it's already a quad-photodiode tech - and it's equally valid, as neither
one us has info on the actual implementation.

In general, before making any claims for photodiodes and pixels, consider the following:
A 'classic' pixel design has a photodiode plus three transistors (you can read about it on Wikipedia):
  • a reset transistor for resetting the photodiode voltage
  • a source-follower transistor for signal amplification
  • a row select transistor

So, one definition of a pixel is a photodiode with three transistors.

The thing is, to improve fill factor and for other design considerations, modern sensors are using transistor sharing.
That is, a single set of the 'classic' transistors is shared between multiple phododiodes.

Transistor sharing is widely used in small sensors.
In the case of these sensors, though, each photodiode has its own microlens.
Thus, the photodiode is the pixel in these designs.

In short, depending on the implementation, a photodiode and a pixel could mean the same thing.

Canon's 'dual-pixel' tech is assumed to be based on a shared-transistor design.
That is, it is a multi-photodiode design.
But since in a shared-transistor design photodiodes are effectively equivalent to pixels (as explained),
Canon's tech could be called multi-pixel design as well.

So, you can stop correcting people who use dual/quad-pixel terminology, as these could in fact be used interchangeably.
The line between between a pixel and a photodiode is blurred in shared-pixel designs.
And the fact that the two photodiodes are read independently for auto-focus further
indicates that these could very well be independent pixels - if they didn't share the
same microlens and color filter.

Also, your claim that there are exactly TWO PHOTODIODES (and that's it!) is not based on fact.
We don't know for sure if Canon's design is a dual-pixel design (your assumption) or a quad-pixel design
(my assumption).

Canon's marking is selling it as a 'dual-pixel' tech likely because it's easier this way to communicate
the concept to the general public.
But we don't know for a fact what the actual implementation is.

So, your TWO PHOTODIODES claim is based on marketing materials, really.
If I were you, I wouldn't put too much weight into these  8).

My assumption for a quad-pixel design is based on simple geometry.
If there are just two photodiodes per pixel, these photodiodes need to be rectangular.
This would be uncommon - if not even a first in the industry.
But with a quad-pixel design, the photodiodes are square just like in any other sensor.

Considering the potential future advantages of a quad-pixel design (e.g. for a non-Bayer sensor),
I'd speculate that Canon would have invested in a quad-pixel design from the start - rather than
designing rectangular photodiodes that later would need to be made square anyway.

Just a speculation, of course - but based on some informed assumptions.

26
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 20, 2014, 12:20:26 PM »
What do you all think are the chances, that the 7D II will surpass the 5D mark iii/1DX on certain things? Such as IQ, ISO, DR or other things?

IMO, the 7DII will at best match the ISO/noise performance of the 5DIII.
And if Canon has finally decided to implement on-chip analog-to-digital conversion (ADC),
DR at low ISO could be better than on the FF cameras.
That's about it, though, in terms of IQ.

Also, just like with the 7D, we might see some features on the 7DII that will later make it
into the higher end cameras.

Overall, it's hard to imagine that the 7DII will offer much more from what you can get
already with the 5DIII today (except for higher frame rate and more pixels per duck).

27
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 19, 2014, 10:06:02 PM »
So, you never know. The 7DII could have the first non-Bayer sensor in a DSLR.

Sigma beat them to it back in 2002 with the SD9 and it's foveon sensor.

Heh. You are right, of course.

28
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 19, 2014, 09:29:39 PM »
You are wildly misinterpreting something you do not understand, and purpetrating a falsehood.

Relax, we are all just speculating here. Even if I'm wrong, so what ??
So, cool down.

29
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 19, 2014, 12:18:31 PM »
You mean your previous post that was bogus and immediately discredited, because your conclusion was based on erroneous interpretation?   ::)
It's all a matter of interpretation, I guess  8).
The arguments against my previous post were extremely weak.

30
EOS Bodies / Re: New Sensor Tech in EOS 7D Mark II [CR2]
« on: June 19, 2014, 12:17:18 PM »
I did a quick drawing of the idea....
The thing about this arrangement is that it uses single-color (monochromatic) filters.
So, you are still 'throwing away' 2/3rds of the incident light.
The trick would be to use more transmissive filters (say R+G, R+B, G+B) and thus throw away less than 2/3rds of light.
Your arrangement does improve resolution, though.

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