Pixel density information

Started Jun 15, 2011 | Discussions
Le Kilt
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Re: As I said...
In reply to bobn2, Jun 18, 2011

bobn2 wrote:

Le Kilt wrote:

ljfinger wrote:

Le Kilt wrote:

I did, comparing reach...

It's not directly useful for that. Pixel pitch is.

It gives me an idea of how many 'pixels per duck' you get, how is that not directly useful?

I would have thought that you'd want pixel spatial frequency (reciprocal of pitch) for that, or do you judge ducks by their area?

Here we go again...

No thanks, I don't want pixel spatial frequency (reciprocal of pitch) for that.

All I'm saying is that pixel density gives you a quick idea of reach, i.e. what some call 'pixels per duck'. I'm not saying anything else. It's not the only criteria for choosing a camera, but it gives you a quick, if basic, idea of reach.

E.g. Look at the pixel density of a 5D2, a 1D4 and a 7D. Tell me that you can't gleen anything from that and I'll tell you you're a dork...(don't worry, I know you won't go that far)
No offense meant to dorks

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John Sheehy
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Re: Utterly irrelevant.
In reply to kebwi, Jun 18, 2011

kebwi wrote:

That seems almost intentionally irrelevant. Clearly, the assumption in any reasonable discussion would be that a comparison is being made within a constant realm of other parameters. The question would be, "all other things being equal, should noise be better or worse with a higher or lower pixel density?" Phrased that way, I believe the question has a relatively clear-cut answer. Noise should be lower in the case of lower density, i.e., larger absolute pixel size.

Not at all; that is the most uncorrelated parameter to image-level noise. The product of quantum efficiency and sensor size comes first, and then, read noise per unit of sensor area, which is not correlated at all to absolute pixel size.

In fact, I can't say I understand the relevance of sensor size at all w.r.t. a discussion of noise.

Maybe you're lost in the Z-axis, and can't see the X and Y axises, and the significance of their scaling?

Can you explain to my how the degree of noise should correlate with the sensor size or the pixel count, as opposed to the pixel size (or by implication the pixel density)?

Can you explain to me how knowing that a 10-micron pixel captured 13 photons is less noisy than knowing that 4 5-micron pixels captured 1, 5, 4, and 3 photons?

-- hide signature --

John

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Robsphoto
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Pixel density calculation and pixel size calculation
In reply to Le Kilt, Jun 18, 2011

Le Kilt wrote:

bobn2 wrote:

Le Kilt wrote:

ljfinger wrote:

Le Kilt wrote:

I did, comparing reach...

It's not directly useful for that. Pixel pitch is.

It gives me an idea of how many 'pixels per duck' you get, how is that not directly useful?

I would have thought that you'd want pixel spatial frequency (reciprocal of pitch) for that, or do you judge ducks by their area?

Here we go again...

No thanks, I don't want pixel spatial frequency (reciprocal of pitch) for that.

All I'm saying is that pixel density gives you a quick idea of reach, i.e. what some call 'pixels per duck'. I'm not saying anything else. It's not the only criteria for choosing a camera, but it gives you a quick, if basic, idea of reach.

E.g. Look at the pixel density of a 5D2, a 1D4 and a 7D. Tell me that you can't gleen anything from that and I'll tell you you're a dork...(don't worry, I know you won't go that far)
No offense meant to dorks

I have prepared a summary of pixel density and pixel size comparisons for a few cameras, and I have found them useful for understanding reach etc. For example, a comparison between the Canon 7D and the Canon 5DII can be seen here:

http://www.robsphotography.co.nz/crop-factor-advantage-7D-5DII.html

and a comparison of the Sony A55 with the Sony A900 here:

http://www.robsphotography.co.nz/Sony-SLT-A55-A900.html

Regards
Rob
http://www.robsphotography.co.nz/crop-factor-advantage-appendix-3.html

Template showing how to compare the pixel density of any two cameras. This template deals with both linear and area relationships.

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bobn2
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Re: As I said...
In reply to Le Kilt, Jun 18, 2011

Le Kilt wrote:

bobn2 wrote:

Le Kilt wrote:

ljfinger wrote:

Le Kilt wrote:

I did, comparing reach...

It's not directly useful for that. Pixel pitch is.

It gives me an idea of how many 'pixels per duck' you get, how is that not directly useful?

I would have thought that you'd want pixel spatial frequency (reciprocal of pitch) for that, or do you judge ducks by their area?

Here we go again...

No thanks, I don't want pixel spatial frequency (reciprocal of pitch) for that.

All I'm saying is that pixel density gives you a quick idea of reach, i.e. what some call 'pixels per duck'. I'm not saying anything else. It's not the only criteria for choosing a camera, but it gives you a quick, if basic, idea of reach.

E.g. Look at the pixel density of a 5D2, a 1D4 and a 7D. Tell me that you can't gleen anything from that and I'll tell you you're a dork...(don't worry, I know you won't go that far)
No offense meant to dorks

I was just asking whether a linear measurement is not more suitable than an area one. After all, with lenses people judge reach either by focal length or angle of view, both of which are linear not area. I'd think if area was the thing we'd be squaring the focal lengths and angles of view.
--
Bob

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bobn2
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Re: Pixel density calculation and pixel size calculation
In reply to Robsphoto, Jun 18, 2011

Robsphoto wrote:

Le Kilt wrote:

bobn2 wrote:

Le Kilt wrote:

ljfinger wrote:

Le Kilt wrote:

I did, comparing reach...

It's not directly useful for that. Pixel pitch is.

It gives me an idea of how many 'pixels per duck' you get, how is that not directly useful?

I would have thought that you'd want pixel spatial frequency (reciprocal of pitch) for that, or do you judge ducks by their area?

Here we go again...

No thanks, I don't want pixel spatial frequency (reciprocal of pitch) for that.

All I'm saying is that pixel density gives you a quick idea of reach, i.e. what some call 'pixels per duck'. I'm not saying anything else. It's not the only criteria for choosing a camera, but it gives you a quick, if basic, idea of reach.

E.g. Look at the pixel density of a 5D2, a 1D4 and a 7D. Tell me that you can't gleen anything from that and I'll tell you you're a dork...(don't worry, I know you won't go that far)
No offense meant to dorks

I have prepared a summary of pixel density and pixel size comparisons for a few cameras, and I have found them useful for understanding reach etc. For example, a comparison between the Canon 7D and the Canon 5DII can be seen here:

http://www.robsphotography.co.nz/crop-factor-advantage-7D-5DII.html

and a comparison of the Sony A55 with the Sony A900 here:

http://www.robsphotography.co.nz/Sony-SLT-A55-A900.html

Regards
Rob
http://www.robsphotography.co.nz/crop-factor-advantage-appendix-3.html

Template showing how to compare the pixel density of any two cameras. This template deals with both linear and area relationships.

Seems like a lot of work. My question remains, would not either pixel pitch or its reciprocal be more appropriate than an area based measure. Seems to me when talking about these things we usually use linear measures. Just wondering. If you can produce a convincing argument, then we'll need to start using square of focal lengths and angles of view.
--
Bob

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Robsphoto
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Big pixels vs small pixels
In reply to Graystar, Jun 18, 2011

Graystar wrote:

sirrah wrote:

Have I missed something or has DPreview stopped stating pixel density in camera specs.

It was there when I last needed to do a comparison but now I cannot find it.

I found it quite useful

That spec was from the days when DPR thought higher megapixel counts were bad, and would complain about smaller noisy pixels by saying things like...

"...and a small sensor with more than a few million pixels is going to be noisy."
http://www.dpreview.com/reviews/panasonicfz8/page12.asp

"A 1/1.8" chip with 8 - or 10 - million pixels is always going to be noisy"
http://www.dpreview.com/reviews/PanasonicFZ50/page12.asp

.

But DPR has changed its tune (or at least turned off the old tune) and appears to not complain about small pixels anymore. That's because the evidence is pretty clear that sensor size, not pixel density, is the determining factor in noise.

The topic of big pixels vs small pixels is becoming more relevant these days. For example, it is strongly rumoured that Sony will shortly announce a 24 megapixel APS-C camera, known as the Sony A77, which will replace the Sony A700. The topic of noise in a 24mp APS-C sensor is being discussed in this thread:

http://forums.dpreview.com/forums/read.asp?forum=1037&message=38660346&changemode=1

For people like myself who are not engineers or physicists, we tend to rely on the views of experts in this field, such as Dr Eric Fossum and Dr Roger Clark. These articles are being discussed in the above thread:

http://www.clarkvision.com/articles/does.pixel.size.matter/

http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p3.html

People who are considering whether or not to buy a 24mp APS-C camera, are being reassured that technological advances will ensure that a 24mp APS-C sensor will not be any "noisier" than a 16mp sensor for high ISO low light images (amazing really)!

I guess the only way to know for sure will be to make proper comparisons of low light images taken by both 16mp and 24mp APS-C cameras.

I am somewhat reassured that smaller pixels are the way of the future after reading this posting from Dr Eric Fossum:

http://forums.dpreview.com/forums/read.asp?forum=1000&message=37409155

Regards
Rob
http://www.robsphotography.co.nz/Sony-A900.html
Examples of the outstanding resolution of images from the full frame Sony A900

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Le Kilt
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Re: Pixel density calculation and pixel size calculation
In reply to Robsphoto, Jun 18, 2011

Robsphoto wrote:

Le Kilt wrote:

bobn2 wrote:

Le Kilt wrote:

ljfinger wrote:

Le Kilt wrote:

I did, comparing reach...

It's not directly useful for that. Pixel pitch is.

It gives me an idea of how many 'pixels per duck' you get, how is that not directly useful?

I would have thought that you'd want pixel spatial frequency (reciprocal of pitch) for that, or do you judge ducks by their area?

Here we go again...

No thanks, I don't want pixel spatial frequency (reciprocal of pitch) for that.

All I'm saying is that pixel density gives you a quick idea of reach, i.e. what some call 'pixels per duck'. I'm not saying anything else. It's not the only criteria for choosing a camera, but it gives you a quick, if basic, idea of reach.

E.g. Look at the pixel density of a 5D2, a 1D4 and a 7D. Tell me that you can't gleen anything from that and I'll tell you you're a dork...(don't worry, I know you won't go that far)
No offense meant to dorks

I have prepared a summary of pixel density and pixel size comparisons for a few cameras, and I have found them useful for understanding reach etc. For example, a comparison between the Canon 7D and the Canon 5DII can be seen here:

http://www.robsphotography.co.nz/crop-factor-advantage-7D-5DII.html

and a comparison of the Sony A55 with the Sony A900 here:

http://www.robsphotography.co.nz/Sony-SLT-A55-A900.html

Regards
Rob
http://www.robsphotography.co.nz/crop-factor-advantage-appendix-3.html

Template showing how to compare the pixel density of any two cameras. This template deals with both linear and area relationships.

Phew! Lots of figures amongst a lot of text, a single excel spreadsheet would probably be easier to read. But that doesn't invalidate your work

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bobn2
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Re: Big pixels vs small pixels
In reply to Robsphoto, Jun 18, 2011

Robsphoto wrote:

Graystar wrote:

sirrah wrote:

Have I missed something or has DPreview stopped stating pixel density in camera specs.

It was there when I last needed to do a comparison but now I cannot find it.

I found it quite useful

That spec was from the days when DPR thought higher megapixel counts were bad, and would complain about smaller noisy pixels by saying things like...

"...and a small sensor with more than a few million pixels is going to be noisy."
http://www.dpreview.com/reviews/panasonicfz8/page12.asp

"A 1/1.8" chip with 8 - or 10 - million pixels is always going to be noisy"
http://www.dpreview.com/reviews/PanasonicFZ50/page12.asp

.

But DPR has changed its tune (or at least turned off the old tune) and appears to not complain about small pixels anymore. That's because the evidence is pretty clear that sensor size, not pixel density, is the determining factor in noise.

The topic of big pixels vs small pixels is becoming more relevant these days. For example, it is strongly rumoured that Sony will shortly announce a 24 megapixel APS-C camera, known as the Sony A77, which will replace the Sony A700. The topic of noise in a 24mp APS-C sensor is being discussed in this thread:

http://forums.dpreview.com/forums/read.asp?forum=1037&message=38660346&changemode=1

For people like myself who are not engineers or physicists, we tend to rely on the views of experts in this field, such as Dr Eric Fossum and Dr Roger Clark. These articles are being discussed in the above thread:

http://www.clarkvision.com/articles/does.pixel.size.matter/

Roger Clark's article is very confused. He compares sensors of both different sensor size and pixel size and then attributes the differences to pixel size. He considers noise and DR at a pixel level, but fails to consider the aggregate effects of different size pixel in the image.

http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p3.html

Emil Martinec's (wonder why you didn't credit him) article on the other hand isn't very confused. Recommended reading.

People who are considering whether or not to buy a 24mp APS-C camera, are being reassured that technological advances will ensure that a 24mp APS-C sensor will not be any "noisier" than a 16mp sensor for high ISO low light images (amazing really)!

Not so amazing, the 'technological advance' involved is simply making the pixel smaller. Generally, scaling pixels down increases DR, because pixel level DR does not change as a pixel is scaled uniformly, and more pixels with teh same DR combine together to give more DR in like portions of a image.

I guess the only way to know for sure will be to make proper comparisons of low light images taken by both 16mp and 24mp APS-C cameras.

Even that won't tell you anything about the general case, only about the two sensors that you have compared. For the general case you need either ot work through the theory or evaluate the overall trends.

I am somewhat reassured that smaller pixels are the way of the future after reading this posting from Dr Eric Fossum:

http://forums.dpreview.com/forums/read.asp?forum=1000&message=37409155

Eric Fossum is also recommended reading.
--
Bob

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Robsphoto
Senior MemberPosts: 1,098
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Re: Pixel density calculation and pixel size calculation
In reply to Le Kilt, Jun 18, 2011

Le Kilt wrote:

Robsphoto wrote:

Le Kilt wrote:

bobn2 wrote:

Le Kilt wrote:

ljfinger wrote:

Le Kilt wrote:

I did, comparing reach...

It's not directly useful for that. Pixel pitch is.

It gives me an idea of how many 'pixels per duck' you get, how is that not directly useful?

I would have thought that you'd want pixel spatial frequency (reciprocal of pitch) for that, or do you judge ducks by their area?

Here we go again...

No thanks, I don't want pixel spatial frequency (reciprocal of pitch) for that.

All I'm saying is that pixel density gives you a quick idea of reach, i.e. what some call 'pixels per duck'. I'm not saying anything else. It's not the only criteria for choosing a camera, but it gives you a quick, if basic, idea of reach.

E.g. Look at the pixel density of a 5D2, a 1D4 and a 7D. Tell me that you can't gleen anything from that and I'll tell you you're a dork...(don't worry, I know you won't go that far)
No offense meant to dorks

I have prepared a summary of pixel density and pixel size comparisons for a few cameras, and I have found them useful for understanding reach etc. For example, a comparison between the Canon 7D and the Canon 5DII can be seen here:

http://www.robsphotography.co.nz/crop-factor-advantage-7D-5DII.html

and a comparison of the Sony A55 with the Sony A900 here:

http://www.robsphotography.co.nz/Sony-SLT-A55-A900.html

Regards
Rob
http://www.robsphotography.co.nz/crop-factor-advantage-appendix-3.html

Template showing how to compare the pixel density of any two cameras. This template deals with both linear and area relationships.

Phew! Lots of figures amongst a lot of text, a single excel spreadsheet would probably be easier to read. But that doesn't invalidate your work

Agreed, I have prepared a single excel spreadsheet that incorporates all the relationships referred to above, and it works quite well. I may add a link to a spreadsheet in my site when I have refined it a bit more and when time permits.

Regards
Rob

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Le Kilt
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Re: As I said...
In reply to bobn2, Jun 18, 2011

bobn2 wrote:

Le Kilt wrote:

bobn2 wrote:

Le Kilt wrote:

ljfinger wrote:

Le Kilt wrote:

I did, comparing reach...

It's not directly useful for that. Pixel pitch is.

It gives me an idea of how many 'pixels per duck' you get, how is that not directly useful?

I would have thought that you'd want pixel spatial frequency (reciprocal of pitch) for that, or do you judge ducks by their area?

Here we go again...

No thanks, I don't want pixel spatial frequency (reciprocal of pitch) for that.

All I'm saying is that pixel density gives you a quick idea of reach, i.e. what some call 'pixels per duck'. I'm not saying anything else. It's not the only criteria for choosing a camera, but it gives you a quick, if basic, idea of reach.

E.g. Look at the pixel density of a 5D2, a 1D4 and a 7D. Tell me that you can't gleen anything from that and I'll tell you you're a dork...(don't worry, I know you won't go that far)
No offense meant to dorks

I was just asking whether a linear measurement is not more suitable than an area one. After all, with lenses people judge reach either by focal length or angle of view, both of which are linear not area. I'd think if area was the thing we'd be squaring the focal lengths and angles of view.
--

Put side by side the pixel densities of a 5D2, a 1D4 and a 7D and tell me that that says nothing to you...

Again, I'm not saying it tells the whole story, or that it's useful to everyone, but if you really can't deduce anything from it, well...
5D2 : 24.3 Kpixels/mm2
1D4 : 30.8 Kpixels/mm2
7D : 53.9 Kpixels/mm2

(If I recall correctly, dpreview used to quote a factor of 10kmpixels, so 2.43, 3.08, 5.39)

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Robsphoto
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Pixel Pitch
In reply to Le Kilt, Jun 19, 2011

Le Kilt wrote:

bobn2 wrote:

Le Kilt wrote:

bobn2 wrote:

Le Kilt wrote:

ljfinger wrote:

Le Kilt wrote:

I did, comparing reach...

It's not directly useful for that. Pixel pitch is.

It gives me an idea of how many 'pixels per duck' you get, how is that not directly useful?

I would have thought that you'd want pixel spatial frequency (reciprocal of pitch) for that, or do you judge ducks by their area?

Here we go again...

No thanks, I don't want pixel spatial frequency (reciprocal of pitch) for that.

All I'm saying is that pixel density gives you a quick idea of reach, i.e. what some call 'pixels per duck'. I'm not saying anything else. It's not the only criteria for choosing a camera, but it gives you a quick, if basic, idea of reach.

E.g. Look at the pixel density of a 5D2, a 1D4 and a 7D. Tell me that you can't gleen anything from that and I'll tell you you're a dork...(don't worry, I know you won't go that far)
No offense meant to dorks

I was just asking whether a linear measurement is not more suitable than an area one. After all, with lenses people judge reach either by focal length or angle of view, both of which are linear not area. I'd think if area was the thing we'd be squaring the focal lengths and angles of view.
--

Put side by side the pixel densities of a 5D2, a 1D4 and a 7D and tell me that that says nothing to you...

Again, I'm not saying it tells the whole story, or that it's useful to everyone, but if you really can't deduce anything from it, well...
5D2 : 24.3 Kpixels/mm2
1D4 : 30.8 Kpixels/mm2
7D : 53.9 Kpixels/mm2

(If I recall correctly, dpreview used to quote a factor of 10kmpixels, so 2.43, 3.08, 5.39)

I have found this July 2008 DPR thread to be very informative:

http://forums.dpreview.com/forums/readflat.asp?forum=1000&thread=28557906&page=1

Initiated by Dr Fossum, the first posting reads as follows:

Most image sensor specialists use pixel size or pitch as a key parameter for the sensor. I would urge DP Review to consider converting to this conventional metric rather than its inverted square (I assume), or provide both (even better).

If you want to be unconventional in a useful way, please consider reporting the active diagonal in mm instead of the 1/X inches system that dates from pre-solid-state image sensor days.

On the other hand, the use of pixel density has generated a lot of almost-amusing forum discussion so it certainly has that value, but I don't think that is what you intended.

I know I am not the first to suggest this, but I wanted to be heard. Keep up the good work,
Eric

Regards
Rob
http://www.robsphotography.co.nz/crop-factor-advantage-appendix-2.html

Template for calculating the approximate width and area of one pixel on the sensor of a digital camera

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Le Kilt
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Re: Pixel Pitch
In reply to Robsphoto, Jun 19, 2011

Robsphoto wrote:

Le Kilt wrote:

bobn2 wrote:

Le Kilt wrote:

bobn2 wrote:

Le Kilt wrote:

ljfinger wrote:

Le Kilt wrote:

I did, comparing reach...

It's not directly useful for that. Pixel pitch is.

It gives me an idea of how many 'pixels per duck' you get, how is that not directly useful?

I would have thought that you'd want pixel spatial frequency (reciprocal of pitch) for that, or do you judge ducks by their area?

Here we go again...

No thanks, I don't want pixel spatial frequency (reciprocal of pitch) for that.

All I'm saying is that pixel density gives you a quick idea of reach, i.e. what some call 'pixels per duck'. I'm not saying anything else. It's not the only criteria for choosing a camera, but it gives you a quick, if basic, idea of reach.

E.g. Look at the pixel density of a 5D2, a 1D4 and a 7D. Tell me that you can't gleen anything from that and I'll tell you you're a dork...(don't worry, I know you won't go that far)
No offense meant to dorks

I was just asking whether a linear measurement is not more suitable than an area one. After all, with lenses people judge reach either by focal length or angle of view, both of which are linear not area. I'd think if area was the thing we'd be squaring the focal lengths and angles of view.
--

Put side by side the pixel densities of a 5D2, a 1D4 and a 7D and tell me that that says nothing to you...

Again, I'm not saying it tells the whole story, or that it's useful to everyone, but if you really can't deduce anything from it, well...
5D2 : 24.3 Kpixels/mm2
1D4 : 30.8 Kpixels/mm2
7D : 53.9 Kpixels/mm2

(If I recall correctly, dpreview used to quote a factor of 10kmpixels, so 2.43, 3.08, 5.39)

I have found this July 2008 DPR thread to be very informative:

http://forums.dpreview.com/forums/readflat.asp?forum=1000&thread=28557906&page=1

Initiated by Dr Fossum, the first posting reads as follows:

Most image sensor specialists use pixel size or pitch as a key parameter for the sensor. I would urge DP Review to consider converting to this conventional metric rather than its inverted square (I assume), or provide both (even better).

If you want to be unconventional in a useful way, please consider reporting the active diagonal in mm instead of the 1/X inches system that dates from pre-solid-state image sensor days.

On the other hand, the use of pixel density has generated a lot of almost-amusing forum discussion so it certainly has that value, but I don't think that is what you intended.

I know I am not the first to suggest this, but I wanted to be heard. Keep up the good work,
Eric

Regards
Rob
http://www.robsphotography.co.nz/crop-factor-advantage-appendix-2.html

Template for calculating the approximate width and area of one pixel on the sensor of a digital camera

Again, loads of blurb due to the mis-use of pixel density. I suppose because dpreview put it on the front page, but could they now put on the specs page, that surely wouldn't kill anyone...?

P.S. sirrah, come back, nobody will bite you !

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Graystar
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Re: Big pixels vs small pixels
In reply to Robsphoto, Jun 19, 2011

Robsphoto wrote:

People who are considering whether or not to buy a 24mp APS-C camera, are being reassured that technological advances will ensure that a 24mp APS-C sensor will not be any "noisier" than a 16mp sensor for high ISO low light images (amazing really)!

For the last 10 years, increased pixel counts haven’t produced noisier images. I’m not sure why it would start doing so now. Noise is based on sensor size and sensor efficiency.

.

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Le Kilt
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Re: Big pixels vs small pixels
In reply to Graystar, Jun 19, 2011

Graystar wrote:

Robsphoto wrote:

People who are considering whether or not to buy a 24mp APS-C camera, are being reassured that technological advances will ensure that a 24mp APS-C sensor will not be any "noisier" than a 16mp sensor for high ISO low light images (amazing really)!

For the last 10 years, increased pixel counts haven’t produced noisier images. I’m not sure why it would start doing so now. Noise is based on sensor size and sensor efficiency.

Yes, it's just that IQ doesn't always follow increased pixel count.

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tom sugnet
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Re: Big pixels vs small pixels
In reply to Graystar, Jun 19, 2011

Of course they have.
That's why photographers use D3 for indoor sports, and not D3x.

Graystar wrote:

For the last 10 years, increased pixel counts haven’t produced noisier images.

.

-- hide signature --

Feel free to visit my photo sites:
http://tom.st , http://www.foto.tom.st

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Great Bustard
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Re: Not Utterly...
In reply to Le Kilt, Jun 19, 2011

Le Kilt wrote:

Great Bustard wrote:

sirrah wrote:

Have I missed something or has DPreview stopped stating pixel density in camera specs.

It was there when I last needed to do a comparison but now I cannot find it.

I found it quite useful

So did I when comparing reach...

Maybe framing, but not reach. You see, two photos would have the same reach if they resolved the same lp/ph for the common portions of the scene. Thus, reach depends not only on the number of pixels the scene is composed of, but the AA filter, and the lens sharpness.

For example, a 17-55 IS has more reach than an 18-55 IS, both used on the same camera.

Pixel density, by itself, gives no useful information.

Is it ever by itself?

The OP led me to believe that they were not interested in sensor size or pixel count, just pixel density.

For sure, if you have two of the three, the third measure can be simply calculated. But you do need two of the three.

What does give useful information is sensor size and pixel count.

How about starting off by asking what sirrah found useful about it?

I find such questions usually get ignored:

http://forums.dpreview.com/forums/read.asp?forum=1000&message=38674474

In any event, I imagine he would have mentioned it somewhere in the ensuing subthread if he had an interest in telling me. Surely he wasn't waiting for me to "pop the question", was he?

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Great Bustard
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If...
In reply to Le Kilt, Jun 19, 2011

Le Kilt wrote:

P.S. sirrah, come back, nobody will bite you !

...sirrah is a hottie, I make no such promise.

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Eric Fossum
Contributing MemberPosts: 699
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Re: Pixel Pitch
In reply to Robsphoto, Jun 19, 2011

An oldie but goodie, and still on the mark from my point of view. And these threads are still entertaining.

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Le Kilt
Senior MemberPosts: 1,662
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Re: If...
In reply to Great Bustard, Jun 19, 2011

Great Bustard wrote:

Le Kilt wrote:

P.S. sirrah, come back, nobody will bite you !

...sirrah is a hottie, I make no such promise.

You devil you...

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Le Kilt
Senior MemberPosts: 1,662
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Re: Not Utterly...
In reply to Great Bustard, Jun 19, 2011

Great Bustard wrote:

Le Kilt wrote:

Great Bustard wrote:

sirrah wrote:

Have I missed something or has DPreview stopped stating pixel density in camera specs.

It was there when I last needed to do a comparison but now I cannot find it.

I found it quite useful

So did I when comparing reach...

Maybe framing, but not reach. You see, two photos would have the same reach if they resolved the same lp/ph for the common portions of the scene. Thus, reach depends not only on the number of pixels the scene is composed of, but the AA filter, and the lens sharpness.

For example, a 17-55 IS has more reach than an 18-55 IS, both used on the same camera.

For small differences maybe, but when you look at the figures for 5D2, 1D4 and 7D, the difference is quite significant.

Pixel density, by itself, gives no useful information.

Is it ever by itself?

The OP led me to believe that they were not interested in sensor size or pixel count, just pixel density.

You got more out of his post than I did

For sure, if you have two of the three, the third measure can be simply calculated. But you do need two of the three.

Nah, it's just a quick at a glance figure that tells you if you need to delve into more detailed stuff (which you probably do anyway...)

What does give useful information is sensor size and pixel count.

How about starting off by asking what sirrah found useful about it?

I find such questions usually get ignored:

http://forums.dpreview.com/forums/read.asp?forum=1000&message=38674474

In any event, I imagine he would have mentioned it somewhere in the ensuing subthread if he had an interest in telling me. Surely he wasn't waiting for me to "pop the question", was he?

Ooooo, you're just being difficult, you devil

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