Updated product pages: Why not pixel density ?

[pidera]

It is sometimes interesting to compare cameras at pixel-density-equivalent iso settings. A sensor with double pixel density can be expected to have a one step worse noise behavior at the pixel level.

Sad the info was omitted.

 

[KLO82]

On the same link, I can see these lines now:

The higher pixel count of the 50D will inevitably show more noise at the pixel level. In principle this additional noise might be expected to average out such that the overall image noise is much the same.

And the lines u quoted cannot be found any more!

I wud say not everyone can accept their (own) mistakes and have the courage to correct those!

DPReview, please answer:

Why have you removed the useful pixel density, that you added to the specifications a couple of years ago?

It was added at a time when dpr staff took the position that the number of pixels said something about its IQ, especially noise characteristics

Despite the fact that the 50D is the newer camera it shows visibly more chroma and luminance noise than the 40D. Considering the 50D's much more tightly packed sensor (4.5 MP/cm² vs 3.1 MP/cm² on the 40D) this comes hardly as a surprise. It would have been unreasonable to expect Canon's engineers to overcome the laws of physics.

http://www.dpreview.com/reviews/canoneos50d/page18.asp
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My Galleries: http://webs.ono.com/igonzalezbordes/index.html

 

[igb]

On the same link, I can see these lines now:

The higher pixel count of the 50D will inevitably show more noise at the pixel level. In principle this additional noise might be expected to average out such that the overall image noise is much the same.

And the lines u quoted cannot be found any more!

I wud say not everyone can accept their (own) mistakes and have the courage to correct those!

And it only took them 3 years!

--
l

 

[bobn2]

It's fun because it must be one of your first full fledged reviews.

No, actually. My name is on the masthead because I wrote the preview (1st half of the review).

Also amusing is thatr, at the time of the first bobn's ban, some other guy posted the same the same plus other links to reviews stating basically the same.

We don't, as a rule, discuss the reason for people being banned - it wouldn't be very professional for me to criticise our users.

People don't get banned for criticising us -

unless they're right, one has to presume.

there are plenty of threads explaining exactly how incompetent, biased and corrupt we apparently are. Being abusive, attacking other posters and just trying to start arguments will, usually after a warning, get you banned.

Richard - dpreview.com

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My Galleries: http://webs.ono.com/igonzalezbordes/index.html

--
Bob

 

[Great Bustard]

It is sometimes interesting to compare cameras at pixel-density-equivalent iso settings. A sensor with double pixel density can be expected to have a one step worse noise behavior at the pixel level.

And yet:

http://forums.dpreview.com/forums/read.asp?forum=1012&message=37549285

Sad the info was omitted.

It was a waste. What you need to know is the sensor size, the number of pixels, the QE (quantum efficiency), and the read noise. In short, the information available here:

http://www.sensorgen.info/

Actually, you'd want info on the AA filter and microlenses as well, but no one has that, so far as I know.

 

[Great Bustard]

is one factor

It would be if the lens and AA filter used on each system had the same MTF at the different enlargements. However, as they usually don't, it doesn't help as much as you would think.

 

[Torkil]

for years, DPReview seemed to hold the view that, the higher the pixel density, the lower the IQ.

this was, and possibly still is, true at a given point in time

Exactly.
And if you - as reader - have this in mind, it is a valid data point to include.

 

[Lee Jay]

for years, DPReview seemed to hold the view that, the higher the pixel density, the lower the IQ.

this was, and possibly still is, true at a given point in time

Exactly.
And if you - as reader - have this in mind, it is a valid data point to include.

I've shown, by testing, that the opposite is largely true.

--
Lee Jay
(see profile for equipment)

 

[jonas ar]

for years, DPReview seemed to hold the view that, the higher the pixel density, the lower the IQ.

this was, and possibly still is, true at a given point in time

however technology advances, and today you might, say, get better IQ with a sensor that has, say, 3x the pixel density of a sensor of 5 years ago. So that piece of data becomes pointless.

the other thing DPreview still need to understand, and get rid of, is that ridiculous concept of "resolution per pixel", because a pixel cannot include resolution.

AND, they should start providing crops that have the same physical size in the real world, not the same pixel size. Their current - erroneous - method will lead them to posting ever smaller crops, and hide the technological advances that have taken place.

And possibly lead people to the false conclusion that the higher the pixel density, the lower the IQ.

They may be the biggest camera review site, but they sure do learn slowly. Or maybe, it's because they are the biggest, that they start behaving like all big corporations.

P.S. I'm aware of, and happy about, all the good things at DPReview. But clearly there are some things they sure do take ages to understand.

I think a quote from Daniel Browning's great six part essay on the subjet is appropriate in this thread:

Overall, DPR is a great site and highly informative; but there are some important flaws, and the DPR war on pixel density is one of them. I'm disappointed to see that Bob Newman has been banned from DPR. I hope I wont be the next one up on the chopping block. /

http://forums.dpreview.com/forums/read.asp?forum=1018&message=32064686

kind regards,

Jonas

 

[bobn2]

I think a quote from Daniel Browning's great six part essay on the subjet is appropriate in this thread:

Overall, DPR is a great site and highly informative; but there are some important flaws, and the DPR war on pixel density is one of them. I'm disappointed to see that Bob Newman has been banned from DPR. I hope I wont be the next one up on the chopping block. /

http://forums.dpreview.com/forums/read.asp?forum=1018&message=32064686

I think that it's easy to see too much of a plot in this, and I did at the time. My own suspicion is that the moderation on this site tends to the capricious and poorly controlled, and that one of the things that gets you banned fastest is irritating the moderators (which, of course, in a well governed system shouldn't be the case). One of the best way to irritate moderators that also consider themselves experts is to consistently challenge their pet theories, and that was precisely what I was doing with the pet theory of the head moderator (former owner and editor) at the time. The 'war on pixel density' seemed to be very much a personal obsession of Phil Askey, he put great store on it, gained a little bit of fame from it, and was even caught red-handed concocting data in trying to support it. In such a circumstance, the likelihood of getting banned was quite high. I suspect the same thing was the case with Joe James' ban. To be fair to Phil, it was necessary to irritate him in several ways at once, but then he did seem to be rather an irascible character, so that wasn't too hard.
--
Bob

 

[igb]

As much as I like to play an armchair therapist (not), I think it's not about alleged good old Phil's issues. PDGate was a team work. You can find current writers' names in the several reviews suggesting that small pixels are bad, in threads denying the evidence, -and it is difficult for me to believe that the pruning of threads/banning of posters was performed solely, even mainly, by Phil-. In my view, the serious dent in DPR's reputation hasn't been fixed.

Which is a pity because all it would take would be an article, clarifying the background and explaining clearly what you, Browing, Martinec, Sheehy to name a few have been trying to make across during some years, for future reference in consideration to the less technically knowledgeable in DPR readership (incidentally the vast majority). That would help clear the confussion generated by DPR (and be good karma for them).

 

[bobn2]

As much as I like to play an armchair therapist (not), I think it's not about alleged good old Phil's issues. PDGate was a team work. You can find current writers' names in the several reviews suggesting that small pixels are bad, in threads denying the evidence, -and it is difficult for me to believe that the pruning of threads/banning of posters was performed solely, even mainly, by Phil-.

I think they tended to do what Phil said, and sometimes add in their own agenda. Having been through many nicks and compared notes with several in the same situation++, I have a better handle on their workings than most, I think. The attitude definitely changed when Phil let go the reigns (hence me posting under my original nick once more - something that would never, ever have happened with Phil in charge) and the moderation definitely did become more even handed. Old habits die hard, though, and while I fully believe what Richard says about no-one being banned for criticising the editorial policy, it certainly hasn't always been so, and I'm not sure that all the mods are quite up to speed with what is the new politburo line.

In my view, the serious dent in DPR's reputation hasn't been fixed.

Not yet. You have to understand their trepidation. We all saw what glasnost led to in the USSR.

Which is a pity because all it would take would be an article, clarifying the background and explaining clearly what you, Browing, Martinec, Sheehy to name a few have been trying to make across during some years, for future reference in consideration to the less technically knowledgeable in DPR readership (incidentally the vast majority). That would help clear the confussion generated by DPR (and be good karma for them).

I have made it clear to the editor that I am available, if he wishes. Still, other publications cover the issues.

There is another problem. If you look at Joe James' equivalence essay (h ttp: josephjamesphotography.com/equivalence - can't cite the URL since it's on the blocked list - go figure) you'll find its grown to include pixel density, noise, exposure - almost everything. A thorough discussion of any of these issues leads inevitably to the conclusion that the digital medium is fundamentally different from the film medium, and ends up undercutting ideas and methods that many hold dear. At least one of the DPR staffers seems to be implacably opposed to discussions about the role of exposure in noise, and when people feel their expertise undermined, they react. if they are DPR staffers, it's quite likely they react by issuing bans.

++ Joe and I shared some (I think) hilarious speculations on the likely discussion at DPR central once, as we went through a sequence of bans. Unfortunately for you lot, their publication here would definitely violate the majority of DPR's posting rules, and we would be quite properly banned, so you're not going to see them.
--
Bob

 

[igb]

As much as I like to play an armchair therapist (not), I think it's not about alleged good old Phil's issues. PDGate was a team work. You can find current writers' names in the several reviews suggesting that small pixels are bad, in threads denying the evidence, -and it is difficult for me to believe that the pruning of threads/banning of posters was performed solely, even mainly, by Phil-.

I think they tended to do what Phil said,

Ah, the Nuremberg defense.

and sometimes add in their own agenda. Having been through many nicks and compared notes with several in the same situation++, I have a better handle on their workings than most, I think. The attitude definitely changed when Phil let go the reigns (hence me posting under my original nick once more - something that would never, ever have happened with Phil in charge) and the moderation definitely did become more even handed. Old habits die hard, though, and while I fully believe what Richard says about no-one being banned for criticising the editorial policy, it certainly hasn't always been so, and I'm not sure that all the mods are quite up to speed with what is the new politburo line.

In my view, the serious dent in DPR's reputation hasn't been fixed.

Not yet. You have to understand their trepidation. We all saw what glasnost led to in the USSR.

Which is a pity because all it would take would be an article, clarifying the background and explaining clearly what you, Browing, Martinec, Sheehy to name a few have been trying to make across during some years, for future reference in consideration to the less technically knowledgeable in DPR readership (incidentally the vast majority). That would help clear the confussion generated by DPR (and be good karma for them).

I have made it clear to the editor that I am available, if he wishes. Still, other publications cover the issues.

There is another problem. If you look at Joe James' equivalence essay (h ttp: josephjamesphotography.com/equivalence - can't cite the URL since it's on the blocked list - go figure) you'll find its grown to include pixel density, noise, exposure - almost everything. A thorough discussion of any of these issues leads inevitably to the conclusion that the digital medium is fundamentally different from the film medium, and ends up undercutting ideas and methods that many hold dear. At least one of the DPR staffers seems to be implacably opposed to discussions about the role of exposure in noise, and when people feel their expertise undermined, they react. if they are DPR staffers, it's quite likely they react by issuing bans.

++ Joe and I shared some (I think) hilarious speculations on the likely discussion at DPR central once, as we went through a sequence of bans. Unfortunately for you lot, their publication here would definitely violate the majority of DPR's posting rules, and we would be quite properly banned, so you're not going to see them.

Oh, you tease. Any chance that they reach wikileaks?

--
Bob

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My Galleries: http://webs.ono.com/igonzalezbordes/index.html

 

[bobn2]

As much as I like to play an armchair therapist (not), I think it's not about alleged good old Phil's issues. PDGate was a team work. You can find current writers' names in the several reviews suggesting that small pixels are bad, in threads denying the evidence, -and it is difficult for me to believe that the pruning of threads/banning of posters was performed solely, even mainly, by Phil-.

I think they tended to do what Phil said,

Ah, the Nuremberg defense.

I'm not defending it, just saying how it happens. If someone is the boss, many people will do what the boss wants, happens everywhere.

++ Joe and I shared some (I think) hilarious speculations on the likely discussion at DPR central once, as we went through a sequence of bans. Unfortunately for you lot, their publication here would definitely violate the majority of DPR's posting rules, and we would be quite properly banned, so you're not going to see them.

Oh, you tease. Any chance that they reach wikileaks?

Probably just after wikileaks gets assimilated by Wikia.
--
Bob

 

[jonas ar]

I think a quote from Daniel Browning's great six part essay on the subjet is appropriate in this thread:

Overall, DPR is a great site and highly informative; but there are some important flaws, and the DPR war on pixel density is one of them. I'm disappointed to see that Bob Newman has been banned from DPR. I hope I wont be the next one up on the chopping block. /

http://forums.dpreview.com/forums/read.asp?forum=1018&message=32064686

The 'war on pixel density' seemed to be very much a personal obsession of Phil Askey, he put great store on it, gained a little bit of fame from it, and was even caught red-handed concocting data in trying to support it.

Red-handed is a too strong expression in my opinion as it implies a deliberate dishonesty (if I understand the expression correctly). I assume you are referring to his blog on downsampling. I'm sure it was an attempt to provide evidence in support for his opinion in good faith.

His failure to engage in the following discussion (as I remember it) was the problematic part and, of course, the blog is still available for eveybody to read without comments
http://blog.dpreview.com/editorial/2008/11/downsampling-to.html

 

[Zamac]

I find pixel pitch confusing

Or perhaps I should say " Not very helpful ".

What I really want to know about a sensor is:-

• The effective percentage of the sensor area covered by the photo sensels - particularly if the sensor is not back lighted. Micro lenses do confuse the issue and should be allowed for. In other words what percent of the incoming light falls on the sensels?

• The sensitivity, i.e. the photon capture ratio.

• The photon capacity of the individual sensels.

All this under standard conditions.

I know this information is not readily available, so think of this as a wish list rather than a request.

 

[Lee Jay]

• The sensitivity, i.e. the photon capture ratio.

That's quantum efficiency, not sensitivity.

--
Lee Jay
(see profile for equipment)

 

[Eric Fossum]

I find pixel pitch confusing

If you find the concept of pixel pitch confusing I recommend that you don't delve into the other data you have wished for.

"Sensel" is another word that I wish I could banish from this forum as contributing only silly obfuscation to the discussion.

 

[bobn2]

I think a quote from Daniel Browning's great six part essay on the subjet is appropriate in this thread:

Overall, DPR is a great site and highly informative; but there are some important flaws, and the DPR war on pixel density is one of them. I'm disappointed to see that Bob Newman has been banned from DPR. I hope I wont be the next one up on the chopping block. /

http://forums.dpreview.com/forums/read.asp?forum=1018&message=32064686

The 'war on pixel density' seemed to be very much a personal obsession of Phil Askey, he put great store on it, gained a little bit of fame from it, and was even caught red-handed concocting data in trying to support it.

Red-handed is a too strong expression in my opinion as it implies a deliberate dishonesty (if I understand the expression correctly). I assume you are referring to his blog on downsampling. I'm sure it was an attempt to provide evidence in support for his opinion in good faith.

Red handed is the right term, in that he was caught in the act (by Emil). I toned my post down from 'falsifying data', because, as you say, I'm not sure he had an intention to do that, but he certainly did concoct data. It was either a midbogglingly poor understanding of the discussion and what he was doing, or an attempt at deliberate dishonesty. I'm very happy to go with the former.

His failure to engage in the following discussion (as I remember it) was the problematic part and, of course, the blog is still available for eveybody to read without comments
http://blog.dpreview.com/editorial/2008/11/downsampling-to.html

Exactly. A bigger man would have 'fessed up to the error (if error it was) and corrected or withdrawn the blog.
--
Bob

 

[bobn2]

I find pixel pitch confusing

Or perhaps I should say " Not very helpful ".

What I really want to know about a sensor is:-

• The effective percentage of the sensor area covered by the photo sensels - particularly if the sensor is not back lighted. Micro lenses do confuse the issue and should be allowed for. In other words what percent of the incoming light falls on the sensels?

• The sensitivity, i.e. the photon capture ratio.

• The photon capacity of the individual sensels.

All this under standard conditions.

I know this information is not readily available, so think of this as a wish list rather than a request.

I do my best:
http://www.sensorgen.info/

that has at least some of the information that you want, albeit in a slightly different form. Originally the data comes from DxO, in a very different form. Anyway, as to your 'wish list':

• The effective percentage of the sensor area covered by the photo sensels - particularly if the sensor is not back lighted. Micro lenses do confuse the issue and should be allowed for. In other words what percent of the incoming light falls on the sensels?

In itself, not a very interesting number. Surely, what we're interested in is the end effect of that area coverage, in terms of the proportion of available photons that the sensor collects. This is known as the 'quantum efficiency', and is one of the pieces of information I give you.

• The sensitivity, i.e. the photon capture ratio.

Those aren't the same thing. What you're calling the 'photon capture ratio' is what is more conventionally called the 'quantum efficiency'. So far as sensitivity is concerned, this is an ambiguous term. In most fields 'sensitivity' would be defined by the smallest phenomenon that you can detect. In the case of a sensor, this is pretty much given by the level of added electronic noise, which would mask out a smaller photonic signal. Conventionally, this is called the 'read noise', and I give you that.

• The photon capacity of the individual sensels.

Sure, I give you that.

Then, of course you have to work out what to do with this information. These three, the QE, read noise and saturation capacity, are rather useful figures of merit for sensor designers, but to understand how they contribute to image formation you need to know rather more, including how many of these pixels go into an image, and the size of the image they are capturing.
--
Bob