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Updated product pages: Why not pixel density ?

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Eric Fossum said:
Zamac said:
I find pixel pitch confusing
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If you find the concept of pixel pitch confusing I recommend that you don't delve into the other data you have wished for.
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Irony is apparently lost on these forums.
Eric Fossum said:
"Sensel" is another word that I wish I could banish from this forum as contributing only silly obfuscation to the discussion.
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I prefer to use the term sensel - I used to employ the term photo-detector element but got lazy - to the refer to the hardware component and pixel to refer to the image component. Though closely related they are not the same (one might make an exception of the Foveon) as the pixel is derived from several photo-detector elements. The distinction may not be important for some people.
 
Great Bustard said:
Roland Karlsson said:
Great Bustard said:
Actually, for photography, it's still the aperture diameter, but most people don't understand that, unfortunately:
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Yeah ... I know. But it does not help knowing it. You may be just 100% right - but if very few agree with you ... youd better do things wrong.
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A while ago, in the Army, when putting up camo nets, my platoon sergeant noted me arguing with others about how they were doing it. He called me aside and said, "You're right, but by the time you convince them, you could have just done it their way." I conceded on the spot.

However, here, on DPR, I have the luxury of not arguing the point in the middle of the desert at noon, so I can take the long route, and patiently wait as more and more come to understand what is going on and why. ;)
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In Danish 'aperture' = 'blænde' and 'f/4' = 'blænde 4', simple as that (but a bit boring, I know ;-)).
 
Steen Bay said:
Great Bustard said:
Roland Karlsson said:
Great Bustard said:
Actually, for photography, it's still the aperture diameter, but most people don't understand that, unfortunately:
Click to expand...
Yeah ... I know. But it does not help knowing it. You may be just 100% right - but if very few agree with you ... youd better do things wrong.
Click to expand...
A while ago, in the Army, when putting up camo nets, my platoon sergeant noted me arguing with others about how they were doing it. He called me aside and said, "You're right, but by the time you convince them, you could have just done it their way." I conceded on the spot.

However, here, on DPR, I have the luxury of not arguing the point in the middle of the desert at noon, so I can take the long route, and patiently wait as more and more come to understand what is going on and why. ;)
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In Danish 'aperture' = 'blænde' and 'f/4' = 'blænde 4', simple as that (but a bit boring, I know ;-)).
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In Denmark you don't have the opportunity to discuss the point in the middle of a desert (though if you discuss it over lunch, it might extend to the dessert).
--
Bob
 
bobn2 said:
In Denmark you don't have the opportunity to discuss the point in the middle of a desert (though if you discuss it over lunch, it might extend to the dessert).
--
Bob
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And yet many "desert movies" have been shot in Denmark :)
 
At last, a sensible follow-up post!

As for

modified fill-factor : I have already conceded in a previous post that quantum efficiency would be more meaningful.

efficiency : I know this is a term of elastic meaning. It is something like the problem with the use of (mechanical) power as a term, meaning to many the maximum force that can be overcome while to the engineer it is the rate at which work is done under specified circumstances. Similarly I think many think of sensitivity in terms of the minimum conditions rather than the ability to distinguish between small changes in light intensity at all levels. I suggested photon capture ratio, but perhaps there could be some better measure.
bobn2 said:
Zamac said:
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.
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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':
bobn2 said:
  • 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?
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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.
bobn2 said:
  • The sensitivity, i.e. the photon capture ratio.
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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.
bobn2 said:
  • The photon capacity of the individual sensels.
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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
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Aperture.

Well, I use the term aperture all the time as an abbreviation for aperture (f/) ratio.

Others can use it as an abbreviation for aperture diameter if they wish.

Strictly speaking aperture is the hole in the iris diaphragm, the hole itself, not its size (from the Latin word meaning "that which is not covered").
 
Zamac said:
Aperture.

Well, I use the term aperture all the time as an abbreviation for aperture (f/) ratio.

Others can use it as an abbreviation for aperture diameter if they wish.

Strictly speaking aperture is the hole in the iris diaphragm, the hole itself, not its size (from the Latin word meaning "that which is not covered").
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You are right.

If someone says that this lens has an aperture ... then he means the actual hole.

If someone says he has an aperture of 50 mm he means the diameter.

If someone says he has an aperture of 2.8 he means the f-stop.

There is no confusion.

Thanx for bringing us back on earth again :)

--
Roland

support http://www.openraw.org/
(Sleeping - so the need to support it is even higher)

X3F tools : http://www.proxel.se/x3f.html
 
pidera said:
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.
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That is not so interesting. If you have the same pixel density but one of the sensors are way bigger it still will have a better overall ISO behaviour.

--
Roland

support http://www.openraw.org/
(Sleeping - so the need to support it is even higher)

X3F tools : http://www.proxel.se/x3f.html
 
antoineb said:
for years, DPReview seemed to hold the view that, the higher the pixel density, the lower the IQ.
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Yes
antoineb said:
this was, and possibly still is, true at a given point in time
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Nope --- its only true if you pixel peep and dont use the entire image to measure IQ.

But you are correct that it gets even less interesting over time. The readout noise gets lower and lower and the percentage of the area that catches photons gets nearer and nearer to 100%.

So - today you can make APS-C sensors that are 16 MP without any problems with high ISO. And this will get better and better.

And .. if you want low ISO (100 or so) ... I assume the APS-C sensor have a quality optimum at several hundreds of megapixels.

--
Roland

support http://www.openraw.org/
(Sleeping - so the need to support it is even higher)

X3F tools : http://www.proxel.se/x3f.html
 
Zamac said:
Aperture.

Well, I use the term aperture all the time as an abbreviation for aperture (f/) ratio.
Click to expand...
More strictly what your doing is abbreviating the phrase 'eff eight', which is itself an abbreviation for 'eff divided by eight', where 'eff' is the focal length. It is entirely correct to say 'the aperture is f/8', or 'the aperture is eff eight' but not 'the aperture is eight'.
Just don't get confused between what you say and what the aperture is.

--
Bob
 
Zamac said:
Eric Fossum said:
Zamac said:
I find pixel pitch confusing
Click to expand...
If you find the concept of pixel pitch confusing I recommend that you don't delve into the other data you have wished for.
Click to expand...
Irony is apparently lost on these forums.
Click to expand...
Yes, now that I understand your subtle use of irony, I am fully amused by your equally ironic statement below.
Zamac said:
I prefer to use the term sensel - I used to employ the term photo-detector element but got lazy - to the refer to the hardware component and pixel to refer to the image component. Though closely related they are not the same (one might make an exception of the Foveon) as the pixel is derived from several photo-detector elements. The distinction may not be important for some people.
Click to expand...
 
Roland Karlsson said:
Le Kilt said:
Please, try reading and quoting all my post before answering, I took the trouble to specify different sensor sizes and same distance and focal length.

"EG take a bird in the center of a 1D4 and a 5D2 and a 7D at same distance and focal length. The 7D gives you more pixels on the subject.

In theory this will enable you to crop more and enlarge more, but IQ will also come into how you then use the result. "

So - pixel count is not more useful for my example ;-)
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My bad - for Canon users the measure might be interesting. Only Canon has mostly one set of lenses and different size sensors.

For us others the measure might be interesting if you have an FF lens, an FF camera body and an APS-C camera body.
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yes, and those who are considering adding a second body or switching from one sensor size to another.
Roland Karlsson said:
And of course only if you take images that are cropped to a certain physical size and if you are interesting in doing the kind of comparisons you are doing.

I would say its not likely that the DPReview community is all that interested overall.
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A poll would be a great idea to find out - ooops, hang on, after the "mirrorless" poll, erm, let's forget it for the moment... ;-)
Roland Karlsson said:
Sorry.
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No problem :-)
Roland Karlsson said:
--
Roland

support http://www.openraw.org/
(Sleeping - so the need to support it is even higher)

X3F tools : http://www.proxel.se/x3f.html
Click to expand...
 
bobn2 said:
Zamac said:
Aperture.

Well, I use the term aperture all the time as an abbreviation for aperture (f/) ratio.
Click to expand...
More strictly what your doing is abbreviating the phrase 'eff eight', which is itself an abbreviation for 'eff divided by eight', where 'eff' is the focal length. It is entirely correct to say 'the aperture is f/8', or 'the aperture is eff eight' but not 'the aperture is eight'.
Just don't get confused between what you say and what the aperture is.
Click to expand...
As a matter of practice I always include the eff when giving a number - e.g. "I used an aperture of f8 for that photo", which is an abbreviation for " I used a focal length to aperture diameter ratio of 8", and in context there is nothing wrong with abbreviations and no confusion results. Although I would not say it myself, I consider it acceptable to say "I prefer to use this lens with an aperture between 8 and 11". No confusion results and to criticize the usage is simply pedantic. There are, of course, occasions where it is very important to specify whether one is referring to the aperture itself (the size of the iris opening) or the ratio with focal length.
 
Yeah, pixel density means nothing.

All new point&shoots have fabulous picture quality, super crisp, and awesome ISO3200.

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

 
tom sugnet said:
Yeah, pixel density means nothing.

All new point&shoots have fabulous picture quality, super crisp, and awesome ISO3200.
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What do those two statements have to do with each other?

--
Lee Jay
(see profile for equipment)
 
Hmmmmm ... this is my take on it.

You had an example where pixel density is interesting. That is if you have cameras of different sensor sizes (like APS-C and FF) and can use the same lens (or the same focal length lens) and take some image (probably wild life) where you crop a lot.

Right?

Then I wonder - why in the first place are you interested in using the larger sensor camera for this application in the first place?

--
Roland

support http://www.openraw.org/
(Sleeping - so the need to support it is even higher)

X3F tools : http://www.proxel.se/x3f.html
 
tom sugnet said:
Yeah, pixel density means nothing.

All new point&shoots have fabulous picture quality, super crisp, and awesome ISO3200.
Click to expand...
You are totally 100% missing the point.

The reason small sensor cameras has problems with image quality is that the sensors are small. If you had an APS-C camera with the same pixel densioty you would have a fantastic IQ.

--
Roland

support http://www.openraw.org/
(Sleeping - so the need to support it is even higher)

X3F tools : http://www.proxel.se/x3f.html
 
Zamac said:
bobn2 said:
Zamac said:
Aperture.

Well, I use the term aperture all the time as an abbreviation for aperture (f/) ratio.
Click to expand...
More strictly what your doing is abbreviating the phrase 'eff eight', which is itself an abbreviation for 'eff divided by eight', where 'eff' is the focal length. It is entirely correct to say 'the aperture is f/8', or 'the aperture is eff eight' but not 'the aperture is eight'.
Just don't get confused between what you say and what the aperture is.
Click to expand...
As a matter of practice I always include the eff when giving a number - e.g. "I used an aperture of f8 for that photo", which is an abbreviation for " I used a focal length to aperture diameter ratio of 8", and in context there is nothing wrong with abbreviations and no confusion results. Although I would not say it myself, I consider it acceptable to say "I prefer to use this lens with an aperture between 8 and 11". No confusion results and to criticize the usage is simply pedantic. There are, of course, occasions where it is very important to specify whether one is referring to the aperture itself (the size of the iris opening) or the ratio with focal length.
Click to expand...
Yes, indeed. The common mistake is to think that, say, f/8 is the same aperture on lenses of different focal lengths. It isn't, because the 'f' is different. That, I think, is the root of the confusion - people thinking f/8 is always the same aperture.
--
Bob
 
bobn2 said:
Zamac said:
bobn2 said:
Zamac said:
Aperture.

Well, I use the term aperture all the time as an abbreviation for aperture (f/) ratio.
Click to expand...
More strictly what your doing is abbreviating the phrase 'eff eight', which is itself an abbreviation for 'eff divided by eight', where 'eff' is the focal length. It is entirely correct to say 'the aperture is f/8', or 'the aperture is eff eight' but not 'the aperture is eight'.
Just don't get confused between what you say and what the aperture is.
Click to expand...
As a matter of practice I always include the eff when giving a number - e.g. "I used an aperture of f8 for that photo", which is an abbreviation for " I used a focal length to aperture diameter ratio of 8", and in context there is nothing wrong with abbreviations and no confusion results. Although I would not say it myself, I consider it acceptable to say "I prefer to use this lens with an aperture between 8 and 11". No confusion results and to criticize the usage is simply pedantic. There are, of course, occasions where it is very important to specify whether one is referring to the aperture itself (the size of the iris opening) or the ratio with focal length.
Click to expand...
Yes, indeed. The common mistake is to think that, say, f/8 is the same aperture on lenses of different focal lengths. It isn't, because the 'f' is different. That, I think, is the root of the confusion - people thinking f/8 is always the same aperture.
Click to expand...
Precisely. Well, not precisely. I don't think most people understand (or care) what the three apertures (virtual, relative, and physical) are, nor understand the relevance in distinguishing between them.

To most, "f/8 = f/8" is about as far as it gets, and the fact that it has a radically different effect on everything but exposure leaves them non-plussed, so they think that the f-ratio is all about exposure, noise is simply a function of ISO, and that bigger sensors are somehow have better tech than smaller sensors and necessarily force you to shoot a more shallow DOF.

All these misunderstandings, and more, can be done away with in one fell swoop by simply making the magical distinction between relative aperture (f-ratio) and virtual aperture (entrance pupil diameter).
 
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