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Author Topic: 40d vs 1Ds Mark 1  (Read 26917 times)
jani
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« Reply #40 on: December 18, 2007, 10:45:07 AM »
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To jerryrock:

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By decreasing both pixel size and circuit area, photodiode area was kept constant. Therefore, the same amount of light can be gathered as on previous sensors.

(http://web.canon.jp/imaging/cmos/technolog..._gathering.html)

The same advances were used in creating the sensor for the 40D and the 1Ds MkIII, and should illuminate the part of the physics that you ignored/didn't know about.
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Jan
jerryrock
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« Reply #41 on: December 18, 2007, 06:52:41 PM »
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To jerryrock:

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By decreasing both pixel size and circuit area, photodiode area was kept constant. Therefore, the same amount of light can be gathered as on previous sensors.

(http://web.canon.jp/imaging/cmos/technolog..._gathering.html)

The same advances were used in creating the sensor for the 40D and the 1Ds MkIII, and should illuminate the part of the physics that you ignored/didn't know about.
[{POST_SNAPBACK}][/a]

To Jani: Here is the other part of the same article that you chose to ignore:

A large CMOS sensor offers better image quality than a smaller because the larger may contain bigger-sized pixels. The relationship between image quality and pixel size can be readily understood if you imagine the pixel as a kind of bucket used to collect not water but light. This micron-sized bucket not only gathers light but also has a photodiode that stores an electrical charge.

[a href=\"http://web.canon.jp/imaging/cmos/technology-e/size.html]http://web.canon.jp/imaging/cmos/technology-e/size.html[/url]

Jerry  
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Gerald J Skrocki
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Misirlou
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« Reply #42 on: December 18, 2007, 09:14:03 PM »
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Quote from: jerryrock,Dec 18 2007, 06:52 PM
(http://web.canon.jp/imaging/cmos/technolog..._gathering.html)

The same advances were used in creating the sensor for the 40D and the 1Ds MkIII, and should illuminate the part of the physics that you ignored/didn't know about.
[{POST_SNAPBACK}][/a]

To Jani: Here is the other part of the same article that you chose to ignore:

A large CMOS sensor offers better image quality than a smaller because the larger may contain bigger-sized pixels. The relationship between image quality and pixel size can be readily understood if you imagine the pixel as a kind of bucket used to collect not water but light. This micron-sized bucket not only gathers light but also has a photodiode that stores an electrical charge.

[a href=\"http://web.canon.jp/imaging/cmos/technology-e/size.html]http://web.canon.jp/imaging/cmos/technology-e/size.html[/url]

Jerry  
[a href=\"index.php?act=findpost&pid=161585\"][{POST_SNAPBACK}][/a]
[/quote]

The analogy may be incomplete. What if the buckets were the same size in both cases, but with the larger sensor, they were merely sitting on a larger piece of floor? This is exactly what some of the posters are getting at. You can't assume that dividing sensor area by number of pixels will give you a reliable estimation of the size of the "buckets." It has been stated that the older sensors didn't squeeze as much detecting space out of their comparitively larger pixel areas as you might expect. Add to that the improvements in microlens technology, and it may be possible that a newer sensor with a higher pixel pitch is actually gathering more photons per pixel than an older, larger sensor.

Look at another analogy. The 8.1 litre engine in my pickup doesn't make anywhere as much horsepower as a 2.5 ltre formula one car engine. But the same laws of physics apply in both cases. It's just that combustion chamber volume is only one variable in the equation. Same thing with these sensors. All other factors being equal, a larger photo site will collect cleaner data. But it would be foolish to assume that all other factors are actually equal with every camera sensor, especially given the rapid development curve we're in with digital cameras.
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jerryrock
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« Reply #43 on: December 18, 2007, 10:59:35 PM »
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"Look at another analogy. The 8.1 litre engine in my pickup doesn't make anywhere as much horsepower as a 2.5 ltre formula one car engine. But the same laws of physics apply in both cases. It's just that combustion chamber volume is only one variable in the equation. Same thing with these sensors. All other factors being equal, a larger photo site will collect cleaner data. But it would be foolish to assume that all other factors are actually equal with every camera sensor, especially given the rapid development curve we're in with digital cameras."

I was just regurgitating the same Canon marketing hype that was presented to me.

But your comparisons of camera sensors to car engines is just over the top!

 
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Gerald J Skrocki
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« Reply #44 on: December 19, 2007, 12:18:11 AM »
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"Look at another analogy. The 8.1 litre engine in my pickup doesn't make anywhere as much horsepower as a 2.5 ltre formula one car engine. But the same laws of physics apply in both cases. It's just that combustion chamber volume is only one variable in the equation. Same thing with these sensors. All other factors being equal, a larger photo site will collect cleaner data. But it would be foolish to assume that all other factors are actually equal with every camera sensor, especially given the rapid development curve we're in with digital cameras."

I was just regurgitating the same Canon marketing hype that was presented to me.

But your comparisons of camera sensors to car engines is just over the top!

 
[a href=\"index.php?act=findpost&pid=161657\"][{POST_SNAPBACK}][/a]

You're missing the point. Did I say car engines were the same as camera sensors? No.

My point was that you can only carry an analogy so far. Some here are arguing that bigger pixels always produce lower noise. All I'm saying is that rules of thumb, such as that one, have their limits. In the automotive world, the old maxim used to be that "nothing beats cubic inches." My example demonstrated that you can't apply any such crude rule without equalizing all the other variables. I'm merely suggesting that maybe the pixel size argument has its limits as well. You're certainly welcome to disagree, but if you're going to argue about matters of sensor physics, you ought to have more evidence to back up your claims than a few simplistic general rules.

My own opinion is that anyone chosing between these cameras based solely on sensor-centered image quality should probably broaden their considerations. These cameras are different in many other ways. For example, it's easier to limit depth of field with a full frame sensor, especially if you're going to use the same lenses. Might be a very big deal for a portrait photographer. Maybe no impact at all for a landscape guy.

A lot of people end up realizing those other factors are really more important to photography than absolute resolution. There's a cranky guy I've heard of that's always going on about whether or not camera controls work well when you're wearing gloves. Maybe you've heard of him?
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jani
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« Reply #45 on: December 19, 2007, 06:19:17 AM »
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To Jani: Here is the other part of the same article that you chose to ignore:
The reason I pointed out that exact quote from the article, is not because I choose to ignore your mantra, or that part of the article, but because you ignore the following facts:

1) Pixel pitch <> pixel well size/photodiode area
2) Pixel pitch <> microlens size

So the smaller sensor (CMOS or whatever) can have BETTER "pixels" than the larger sensor.

I should think that Canon's illustration makes that clear.

If you reread the excerpt from Canon's technology pages, you might see what we're getting at here:

I can have a pixel pitch of 5 meters, yet it helps nothing at all if the microlens is only 5 m and the sensor well is 4. Sure, my 12 megapixel sensor would cover an area of 300 km, but the image quality might not be so great compared to a 10 megapixel sensor with microlenses covering  25 m and sensor wells of 16 m.

I suggest that you stop presuming that everyone else on this forum knows less than you about what's going on and perhaps assume a slightly humbler attitude. The issues you raise are hardly new, and have been discussed at length in this and other technically-minded fora before, with contributions from people who do know how sensors are made and how technology progresses.
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Jan
jerryrock
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« Reply #46 on: December 19, 2007, 09:29:28 AM »
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"I suggest that you stop presuming that everyone else on this forum knows less than you about what's going on and perhaps assume a slightly humbler attitude."

Look Jani,

I expressed my opinion in this tread quite sometime ago and stand by it. You chose to resurrect this discussion by directing your comment to me.  I do not presume to know any more or less than the other posters in this thread. What I do know is based on five years of experience with the Canon EOS 1Ds (the original, full frame, 11.1 megapixel) professional camera and a degree in Visual Communication.

Your suggestion is both rude and out of line.

Jerry
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Gerald J Skrocki
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jani
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« Reply #47 on: December 30, 2007, 05:19:53 PM »
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Look Jani,

I expressed my opinion in this tread quite sometime ago and stand by it. You chose to resurrect this discussion by directing your comment to me.
Yes, I did, because there was a rather significant point that wasn't addressed by other posters.

This is quite normal in a web forum discussion, on netnews, and even in more traditional media.

Quote
I do not presume to know any more or less than the other posters in this thread. What I do know is based on five years of experience with the Canon EOS 1Ds (the original, full frame, 11.1 megapixel) professional camera and a degree in Visual Communication.

Does this mean that you admit that your claims have certain technical weaknesses, or are you now claiming that this one-camera experience and degree makes you more qualified?

Perhaps you do not see it that way, but what you're suggesting goes against what Canon claims, as well as what other, experienced posters to this forum seem to understand as how the physics might work.

You have not put forward convincing evidence, yet you keep on claiming that you're right and others who put forward rather well-documented, contradicting evidence are wrong.

And do forgive me if I'm wrong, but Visual Communication does not appear to be an engineering or science degree, and is as such largely irrelevant to the technical issues at hand.
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Jan
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