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Author Topic: 9% larger pixel size on 1D X - how does that translate IQ-wise?  (Read 11267 times)

Redreflex

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9% larger pixel size on 1D X - how does that translate IQ-wise?
« on: October 18, 2011, 05:38:38 AM »
Here's a comparison of relative pixel sizes. Quote from Chuck Westfall (Canon USA Pro Engineering division) via dpreview: (http://www.dpreview.com/articles/5149972341/canon-eos-1d-x-overview)

When asked to for the biggest improvement in the new camera, Westfall stresses that every aspect of the camera has been re-assessed but finally concludes: 'If you had to highlight just one thing, I'd say the sensor. It's a new level for us in terms of image quality.'

'There's a couple of things that we consider when we think about IQ: number one on this sensor is noise. It's clear the noise level is better than in the 1D Mk IV or the 1DS III. The pixel size is larger than in the 1DS III or 5D Mark II (6.95 microns, versus 6.4) and the difference is even more striking compared to the 5.7 micron pixels in the 1D Mark IV. That helps us in terms of light capturing ability and increases the signal to noise ratio. In turn, that does nothing but help the dynamic range of the camera.'


The pixel size is 8.5% larger in the 1D X compared to 1Ds3 or 5Dm2.

Everything else being equal, how does that translate into real-world image quality improvement? (I accept there'll be other factors to consider other than pixel size)

« Last Edit: October 18, 2011, 05:51:14 AM by Redreflex »

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9% larger pixel size on 1D X - how does that translate IQ-wise?
« on: October 18, 2011, 05:38:38 AM »

Gothmoth

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #1 on: October 18, 2011, 05:46:32 AM »
The pixel size is 8.5% larger in the 1D X compared to 1Ds3 or 5Dm2.

the diameter is 8.5% larger.


Edwin Herdman

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #2 on: October 18, 2011, 07:06:55 AM »
Chuck Westfall demonstrates he isn't an engineer; nothing else.  He's a good guy but don't forget he's a PR guy and these numbers might as well have been pulled out of a hat as far as his description of them here.

I accept as true that at some point smaller-size pixels do run into IQ problems.  The actual point where you'd draw the line for IQ is not guaranteed to be the point where they are drawing the line, because they have to produce these sensors in bulk and so a smaller pixel pitch could translate into higher reject rates for chips.

I think Gothmoth is right here; this is discussing (as usual) pixel diameter.  9% would be less than a generational change in technology would improve ISO performance, but it fares better than 9% in comparison with the Mark IV (less by far in comparison with the 1Ds Mark III though).  I'm not positive my numbers are right, but squaring both micron sizes (1D X versus 1D Mark IV) gives me an end ratio of (1D X micron size / 1D Mark IV size) = 1.486... times the sensor size.  You'll note that's a little bit larger than the 1.3x crop factor would allow for (again, I might be making an error here; though it doesn't make sense to normalize one pixel size to the other).  It goes to show that, once again, sheer sensor size trumps other considerations, but otherwise this isn't a straight comparison - for a 1.3x sensor camera to compete on a per-pixel basis (remembering that noise or any other picture attribute is meaningless on a single pixel basis) with the 1D X it would have to have a low megapixel count, by any modern standard, which is why I wondered for a moment if it wouldn't make sense to normalize the Mark IV pixels to their size on a full frame sensor (this would be a silly comparison, of course, since they'd be even slightly larger than the 1D X pixels).

My feeling is that Canon is joining Nikon (actually, they did some time ago as a German rep for Canon described a relationship between noise and pixel density which sounded a lot like the typical Nikon statement) in downplaying the importance of more megapixels, but the real calculations on the tradeoffs between ISO and production being done are likely trade secrets and not revealed.  Furthermore, many shooters simply are not going to buy this public argument because they require as much resolution as possible.  It will be interesting to observe the silence when a 5D Mark II replacement comes out that is also full frame but features a smaller pixel pitch.

The interesting question here, however, is one I would think holds true even if you believe (and I admit it's quite possible) that they actually aren't obfuscating the truth with marketing, and that there is this relationship (and they've only simplified it a bit for the masses) - what are the assumptions about the market use of cameras that leads them to downplay megapixel counts on one camera and not another?  The shooting rate of this new 1D X is limited by more than just the number of pixels on the sensor, such as the CPU (in this case, interestingly, we see that the new DIGIC 5 does indeed come in various "flavors," this one being the "5+" but still used in a pair for the new camera, so perhaps a sole 5+ will be the CPU for more mainstream DSLRs, and the "DIGIC 5" may be for compacts, if I have not misread this) and the actual hardware of the SLR mechanisms - in combination, a fast mirror return rate with a high megapixel count sensor would send much more data to the sensor than seen here.  If they're using two DIGIC 5+ CPUs, we don't have proof that these CPUs are being taxed to the limit, but it doesn't seem likely that just one would suffice.

9% larger pixels seems less significant to me (and I think the numbers back this up) than just the typical generational change in the sensor production technology and other patented elements that are esoteric and do not follow this easy (and I think misleading) apparent mathematical relationship - like improving microlenses, or most importantly improvements in the photon to signal capture chain (including the ADC).
« Last Edit: October 18, 2011, 07:20:07 AM by Edwin Herdman »

Ivar

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #3 on: October 18, 2011, 08:37:14 AM »
The only thing needed to be be done for a proper comparison between the technologies (NB! not sensor sizes) is to compare the output for exactly the same sensor area.

Thus, take a high ISO shot (highest native for the 1D mk4 as to stay at the hardware level) with both, with the 1D Mk4 & 1Dx, crop the latter one to the 1.3x (the 1Dx has then 13.85MP left out of 18MP) and downsize the bigger 1D Mk4 file to 13.85MP.  This way, it is possible to compare the technologies rather than the cameras.

The results - the 1Dx might be better per area, but it is not as good as marketing tries to show, it is the sensor size what adds most to the equation, not the individual size of the sensel. 

P.S obviously the real test can be only done when the new X is available.

NotABunny

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #4 on: October 18, 2011, 08:38:03 AM »
Everything else being equal, how does that translate into real-world image quality improvement?

Umm, but nothing else is equal. They are launching a new platform, DIGIC 5: processor and sensor technology.

It's far more interesting to look at the maximum native ISO: 51200. They are confident that this is the maximum native ISO which delivers acceptable quality when a shot must be taken. The maximum native ISO of the 5D2 is 6400, so 3 stops more is mind-bending.
« Last Edit: October 18, 2011, 08:39:40 AM by NotABunny »

mreco99

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #5 on: October 18, 2011, 08:48:10 AM »
i guess some actual image output samples will be available very soon, within the next two weeks.

Redreflex

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #6 on: October 18, 2011, 09:06:19 AM »
9% larger pixels seems less significant to me (and I think the numbers back this up) than just the typical generational change in the sensor production technology and other patented elements that are esoteric and do not follow this easy (and I think misleading) apparent mathematical relationship - like improving microlenses, or most importantly improvements in the photon to signal capture chain (including the ADC).

That seems sensible. It's just interesting that a Canon USA engineer chose pixel size as the one thing to highlight, and not all the other aspects.

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #6 on: October 18, 2011, 09:06:19 AM »

archangelrichard

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #7 on: October 18, 2011, 09:12:53 AM »
There is much more to this than just pixel size / count (and that part is often overstated), they have redesigned the microlenses, etc. to improve image quality

the 18 MP is not just about "bigger pixels" but about processing speed - I think that was a target and they had to reduce MP count to keep processing speed at target (note also they have gone from 8 bit to 16bit internally for video processing speed)

I think people need to look beyond the specs to what this accomplishes, what kind of camera this is, where it fits in the marketplace

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #8 on: October 18, 2011, 09:14:10 AM »
Don't expect too much from our main man Chuckie, he's the same guy who said the 50D was two stops better than the 40D at high ISO.  ::)
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Redreflex

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #9 on: October 18, 2011, 09:27:07 AM »
Don't expect too much from our main man Chuckie, he's the same guy who said the 50D was two stops better than the 40D at high ISO.  ::)

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Ivar

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #10 on: October 18, 2011, 09:27:20 AM »
I hope this all stands true.

However, Sony is able to do 24MP@12fps (also on paper like the 1Dx but released in a couple of weeks instead of March). Ok, it will do it at 12bits, but I believe this is the last thing in the chain giving the real tangible differences, what concerns anything over 12bits.

There is much more to this than just pixel size / count (and that part is often overstated), they have redesigned the microlenses, etc. to improve image quality

the 18 MP is not just about "bigger pixels" but about processing speed - I think that was a target and they had to reduce MP count to keep processing speed at target (note also they have gone from 8 bit to 16bit internally for video processing speed)

I think people need to look beyond the specs to what this accomplishes, what kind of camera this is, where it fits in the marketplace

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #11 on: October 18, 2011, 11:35:20 AM »
9% larger pixels seems less significant to me (and I think the numbers back this up) than just the typical generational change in the sensor production technology and other patented elements that are esoteric and do not follow this easy (and I think misleading) apparent mathematical relationship - like improving microlenses, or most importantly improvements in the photon to signal capture chain (including the ADC).

That seems sensible. It's just interesting that a Canon USA engineer chose pixel size as the one thing to highlight, and not all the other aspects.

Well, since the number of pixels got smaller, he sure as heck couldn't highlight that, right?   :P
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Redreflex

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #12 on: October 18, 2011, 12:22:05 PM »
9% larger pixels seems less significant to me (and I think the numbers back this up) than just the typical generational change in the sensor production technology and other patented elements that are esoteric and do not follow this easy (and I think misleading) apparent mathematical relationship - like improving microlenses, or most importantly improvements in the photon to signal capture chain (including the ADC).

That seems sensible. It's just interesting that a Canon USA engineer chose pixel size as the one thing to highlight, and not all the other aspects.

Well, since the number of pixels got smaller, he sure as heck couldn't highlight that, right?   :P

I think that's the definition of marketing and PR

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #12 on: October 18, 2011, 12:22:05 PM »

Canon-F1

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #13 on: October 18, 2011, 02:34:45 PM »
The pixel size is 8.5% larger in the 1D X compared to 1Ds3 or 5Dm2.

the diameter is 8.5% larger.

you mean that the pixel AREA has seen a bigger increase then 8.5%?
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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #14 on: October 18, 2011, 05:21:47 PM »
I hope this all stands true.

However, Sony is able to do 24MP@12fps (also on paper like the 1Dx but released in a couple of weeks instead of March). Ok, it will do it at 12bits, but I believe this is the last thing in the chain giving the real tangible differences, what concerns anything over 12bits.

There is much more to this than just pixel size / count (and that part is often overstated), they have redesigned the microlenses, etc. to improve image quality

the 18 MP is not just about "bigger pixels" but about processing speed - I think that was a target and they had to reduce MP count to keep processing speed at target (note also they have gone from 8 bit to 16bit internally for video processing speed)

I think people need to look beyond the specs to what this accomplishes, what kind of camera this is, where it fits in the marketplace

Ivar, don't disregard the difference between 12-bit and 14-bit files.  I'm still waiting to see 16-bit RAWs on our cameras.  the difference, whether perceiving it on-screen or printed, is huge in terms of smooth gradations and color accuracy.

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Re: 9% larger pixel size on 1D X - how does that translate IQ-wise?
« Reply #14 on: October 18, 2011, 05:21:47 PM »