Megapixels to Sensor Sizes - Best Matches?

Discussion in 'Digital Photography' started by Paul D. Sullivan, Feb 7, 2007.

  1. I read an article on Cnet about how 8 or 10 megapixel cameras are
    not as good as they could be because their megapixel capability
    does not match sensor sizes well. If you buy a camera with 8 or
    10 megapixels and they have some really small sensor, the extra
    megapixels will not be realized in terms of quality.

    Got me thinking - what are some of the best matches of megapixel
    capability to sensor size?

    How does the Canon a640 mentioned in the article hold up?

    How does the Canon S3 IS hold up?

    Olympus Evolt series with those 4/3rds sized sensors?

    Do Fuji, Kodak, Nikon and others have a good ratio on average, or
    are certain models better than others?

    I'd like to think that consumers aren't getting screwed when they
    want to get to an 8 or 10 megapixel camera, and wanted to ask
    some of ya'all here about it so I could learn what up.

    Any helpful answers would be appreciated.

    Thanks
     
    Paul D. Sullivan, Feb 7, 2007
    #1
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  2. Paul D. Sullivan

    skip Guest

    "Paul D. Sullivan" <> wrote in message
    news:pDlyh.9047$xu4.4693@trndny04...

    <snip>

    >I read an article on Cnet about how 8 or 10 megapixel cameras are not as
    >good as they could be because their megapixel capability does not match
    >sensor sizes well. If you buy a camera with 8 or 10 megapixels and they
    >have some really small sensor, the extra megapixels will not be realized in
    >terms of quality.
    >
    > Got me thinking - what are some of the best matches of megapixel
    > capability to sensor size?


    <snip>

    > How does the Canon S3 IS hold up?
    >


    To my eye the Canon S2 IS (one of which I own) with 5 Megapixels is less
    noisy than its S3 successor with 6 Megapixels.

    You can judge for yourself by looking at a side by side comparison here:

    http://www.dpreview.com/reviews/canons3is/page6.asp

    My personal and highly unscientific take on this is that 4 Megapixels is
    about optimal for the small sensor point and shoot cameras I've used. I've
    made sharp 8x10 Prints from images taken with a 2 Megapixel Nikon 950 on a
    tripod.

    The opinions of others are likely to vary.
     
    skip, Feb 7, 2007
    #2
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  3. Paul D. Sullivan wrote:
    > I read an article on Cnet about how 8 or 10 megapixel cameras are
    > not as good as they could be because their megapixel capability
    > does not match sensor sizes well. If you buy a camera with 8 or
    > 10 megapixels and they have some really small sensor, the extra
    > megapixels will not be realized in terms of quality.
    >
    > Got me thinking - what are some of the best matches of megapixel
    > capability to sensor size?


    While one can't prove there is an optimum, because the
    trade space of size of a pixel versus performance just keeps
    getting better with larger pixels, I personally think the
    about 6 to 8 micron pixel pitch is the ideal size. That pitch
    allows many pixels to be crammed into an small sensor
    (e.g. about 8 megapixels in APS-C), while still collecting
    enough photons for great performance, including high ISO
    performance. Collecting about 50,000 photons per pixel
    produces beautiful images, and the 6 to 6 micron pixel pitches
    do that. This is the performance point of many DSLRs.

    Quantitative data on sensor performance can be found at:
    http://www.clarkvision.com/imagedetail/digital.sensor.performance.summary
    >
    > How does the Canon a640 mentioned in the article hold up?
    >
    > How does the Canon S3 IS hold up?


    S3: 2-micron pixel pith: performance near the bottom of the range on the
    plots on the above page.
    >
    > Olympus Evolt series with those 4/3rds sized sensors?


    E300: 5.3 micron pitch should plot in the mid range of performance:
    below most DSLRs and above most P&S.
    >
    > Do Fuji, Kodak, Nikon and others have a good ratio on average, or
    > are certain models better than others?


    Look at each model. The newer P&S cameras seem to cram in megapixels,
    and performance per pixel suffers. Most notably, the high iso
    performance (Figures 6 and 7 on the above web page).
    >
    > I'd like to think that consumers aren't getting screwed when they
    > want to get to an 8 or 10 megapixel camera, and wanted to ask
    > some of ya'all here about it so I could learn what up.
    >
    > Any helpful answers would be appreciated.
    >
    > Thanks


    Manufacturers are trying to hide the noise and low performance
    issues by average pixel in their noise reduction software. So what any
    one camera produces out of camera can be confusing and the
    manufacturers are trying to get you to think they have a better
    solution. But CCD and CMOS sensors have noise dominated by photon
    counting statistics over most of their range. That is a fundamental
    limit, so collecting more photons with larger pixels is the only
    major performance metric.

    Other related info at:
    http://www.clarkvision.com/imagedetail/index.html#sensor_analysis

    Roger
    Photos at: http://www.clarkvision.com
     
    Roger N. Clark (change username to rnclark), Feb 8, 2007
    #3
  4. Paul D. Sullivan

    ray Guest

    On Wed, 07 Feb 2007 14:46:45 +0000, Paul D. Sullivan wrote:

    > I read an article on Cnet about how 8 or 10 megapixel cameras are
    > not as good as they could be because their megapixel capability
    > does not match sensor sizes well. If you buy a camera with 8 or
    > 10 megapixels and they have some really small sensor, the extra
    > megapixels will not be realized in terms of quality.
    >
    > Got me thinking - what are some of the best matches of megapixel
    > capability to sensor size?
    >
    > How does the Canon a640 mentioned in the article hold up?
    >
    > How does the Canon S3 IS hold up?
    >
    > Olympus Evolt series with those 4/3rds sized sensors?
    >
    > Do Fuji, Kodak, Nikon and others have a good ratio on average, or
    > are certain models better than others?
    >
    > I'd like to think that consumers aren't getting screwed when they
    > want to get to an 8 or 10 megapixel camera, and wanted to ask
    > some of ya'all here about it so I could learn what up.
    >
    > Any helpful answers would be appreciated.
    >
    > Thanks


    FWIW - I remember two or three years ago reading that the latest crop of 8
    mp cameras (pretty much state of the art then) were suffering from
    crosstalk and not giving the results that had been anticipated.
     
    ray, Feb 8, 2007
    #4
  5. Great reply. Thank you very much.

    How does the Canon A640 hold up, if you don't mind? Does it give
    a good combination for a 10 megapixel camera?

    > Paul D. Sullivan wrote:
    >> I read an article on Cnet about how 8 or 10 megapixel cameras
    >> are not as good as they could be because their megapixel
    >> capability does not match sensor sizes well. If you buy a
    >> camera with 8 or 10 megapixels and they have some really
    >> small sensor, the extra megapixels will not be realized in
    >> terms of quality. Got me thinking - what are some of the best
    >> matches of
    >> megapixel capability to sensor size?

    >
    > While one can't prove there is an optimum, because the
    > trade space of size of a pixel versus performance just keeps
    > getting better with larger pixels, I personally think the
    > about 6 to 8 micron pixel pitch is the ideal size. That pitch
    > allows many pixels to be crammed into an small sensor
    > (e.g. about 8 megapixels in APS-C), while still collecting
    > enough photons for great performance, including high ISO
    > performance. Collecting about 50,000 photons per pixel
    > produces beautiful images, and the 6 to 6 micron pixel pitches
    > do that. This is the performance point of many DSLRs.
    >
    > Quantitative data on sensor performance can be found at:
    > http://www.clarkvision.com/imagedetail/digital.sensor.performance.summary
    >>
    >> How does the Canon a640 mentioned in the article hold up?
    >>
    >> How does the Canon S3 IS hold up?

    >
    > S3: 2-micron pixel pith: performance near the bottom of the
    > range on the plots on the above page.
    >>
    >> Olympus Evolt series with those 4/3rds sized sensors?

    >
    > E300: 5.3 micron pitch should plot in the mid range of
    > performance: below most DSLRs and above most P&S.
    >>
    >> Do Fuji, Kodak, Nikon and others have a good ratio on
    >> average, or are certain models better than others?

    >
    > Look at each model. The newer P&S cameras seem to cram in
    > megapixels, and performance per pixel suffers. Most notably,
    > the high iso performance (Figures 6 and 7 on the above web
    > page).
    >>
    >> I'd like to think that consumers aren't getting screwed when
    >> they want to get to an 8 or 10 megapixel camera, and wanted
    >> to ask some of ya'all here about it so I could learn what up.
    >>
    >> Any helpful answers would be appreciated.
    >>
    >> Thanks

    >
    > Manufacturers are trying to hide the noise and low performance
    > issues by average pixel in their noise reduction software. So
    > what any one camera produces out of camera can be confusing
    > and the manufacturers are trying to get you to think they have
    > a better solution. But CCD and CMOS sensors have noise
    > dominated by photon counting statistics over most of their
    > range. That is a fundamental limit, so collecting more
    > photons with larger pixels is the only major performance
    > metric.
    >
    > Other related info at:
    > http://www.clarkvision.com/imagedetail/index.html#sensor_analysis
    >
    > Roger
    > Photos at: http://www.clarkvision.com
     
    Paul D. Sullivan, Feb 8, 2007
    #5
  6. Yeah, that's kind of what that article was saying.

    For me, I would want 8mp so I can get 300 dpi of resolvable
    detail on 8x10 prints. I almost never go over 8x10, so figure
    8mp is the sweet spot.

    But I'd hate to think that extra 3 megapixels overy my 5
    megapixel C5050 was simply "hot air" and not worth the
    investment.

    > FWIW - I remember two or three years ago reading that the
    > latest crop of 8 mp cameras (pretty much state of the art
    > then) were suffering from crosstalk and not giving the results
    > that had been anticipated.
     
    Paul D. Sullivan, Feb 8, 2007
    #6
  7. That's a ton of data that I can't begin to understand. I wonder
    if you would be so kind as to help summarize it in simpler terms?

    For example, you indicate that the 4/3rds in the Oly Evolt is mid
    range. That makes sense and I can understand that.

    But I guess I'd further ask, what megapixel size is that sensor
    able to resolve properly? Is 8 mp a good fit for that 4/3rds
    sensor? Would it max out at 8 mp or would it also work well for
    10 mp or 12 mp too?

    Thanks much. :)

    > While one can't prove there is an optimum, because the
    > trade space of size of a pixel versus performance just keeps
    > getting better with larger pixels, I personally think the
    > about 6 to 8 micron pixel pitch is the ideal size. That pitch
    > allows many pixels to be crammed into an small sensor
    > (e.g. about 8 megapixels in APS-C), while still collecting
    > enough photons for great performance, including high ISO
    > performance. Collecting about 50,000 photons per pixel
    > produces beautiful images, and the 6 to 6 micron pixel pitches
    > do that. This is the performance point of many DSLRs.
     
    Paul D. Sullivan, Feb 8, 2007
    #7
  8. Paul D. Sullivan

    ASAAR Guest

    On Thu, 08 Feb 2007 06:36:46 GMT, Paul D. Sullivan wrote:

    > For me, I would want 8mp so I can get 300 dpi of resolvable
    > detail on 8x10 prints. I almost never go over 8x10, so figure
    > 8mp is the sweet spot.
    >
    > But I'd hate to think that extra 3 megapixels overy my 5
    > megapixel C5050 was simply "hot air" and not worth the
    > investment.


    It's not hot air, but it may provide less than you expect. From
    looking at some of dpreview's resolution tests for various cameras,
    I'd say that based on the resolution of the 7mp sensor in Canon's
    A620, the 10mp sensor in the A640 greater resolution, but only the
    increase that you'd expect to see going from 7mp to 8mp. It may be
    a different story for other cameras with other sensors.

    It's very easy to see exactly what you'll get by going from the
    C5050 to a specific camera with an 8mp sensor. Dpreview has a full
    review for the C5050. Look at the resolution chart sections and the
    studio scene comparisons. Some of the items will probably have
    changed in the studio scenes over the years, but there should be
    several that are still being used. Don't look at what appears on
    the web page, but download the full sized studio scene images (not
    all of them, just choose a couple of the better, low ISO versions).
    These should each be several MB in size. Differences in resolvable
    detail should be obvious using whatever program you normally use to
    view photos on your computer. The last review web page shows a
    sample image gallery containing pictures taken with the camera being
    reviewed. These will be of different types of pictures more
    representative of the shots real people take - no artificial test
    images. So you can download a few of these for more comparisons.
    These should show you exactly what you can expect from any of the
    reviewed cameras. The best place to quickly find them is here:

    http://www.dpreview.com/reviews/default.asp?view=alpha
     
    ASAAR, Feb 8, 2007
    #8
  9. Thank you again. So the 10mp and sensor configuration in the
    A640 really is not able to fully resolve those 10mp in a useful
    or proper way? You are not truly getting the full possible
    benefit from those 10 megapixels because the sensor is too small
    inside the camera?

    > It's not hot air, but it may provide less than you expect.
    > From looking at some of dpreview's resolution tests for
    > various cameras, I'd say that based on the resolution of the
    > 7mp sensor in Canon's A620, the 10mp sensor in the A640
    > greater resolution, but only the increase that you'd expect to
    > see going from 7mp to 8mp. It may be a different story for
    > other cameras with other sensors.
     
    Paul D. Sullivan, Feb 8, 2007
    #9
  10. Paul D. Sullivan

    ASAAR Guest

    On Thu, 08 Feb 2007 08:01:35 GMT, Paul D. Sullivan wrote:

    > Thank you again. So the 10mp and sensor configuration in the
    > A640 really is not able to fully resolve those 10mp in a useful
    > or proper way? You are not truly getting the full possible
    > benefit from those 10 megapixels because the sensor is too small
    > inside the camera?


    Not at all. I don't really understand how the 10mp sensor would
    be considered to be not useful or not be able to resolve detail
    properly. Some may say that it shows that Canon should have used a
    larger sensor if they wanted to take the A6xx series up to 10mp, but
    that probably would have been a mistake. It would have almost
    certainly resulted in a camera that wasn't an incremental upgrade
    from previous versions. The camera and lens probably would have
    been larger. Someone owning a previous model such as the A610 or
    A620 that had also purchased the wide or tele lens adapters may have
    found themselves unable to use them with the A640. The A640's 10mp
    sensor won't have the resolution of a good 10mp DSLR, but the
    resolution it does provide is probably about as good as the
    resolution you'd get from other 10mp P&S cameras using the same size
    sensor. All I meant was to say that higher resolution alone is not
    a good reason to upgrade, if you'll only be upgrading from a 7 or
    8mp sensor, since the benefit is not as great as the numbers
    indicate. The difference between the A640's 10mp sensor and any P&S
    camera's 5mp sensor should be considerable, and the newer cameras
    should also be faster, much easier on batteries, and have better
    high ISO performance. The reviews indicate that even though more
    pixels are squeezed into the same size sensor that is used by the
    7mp sensor in the A620 (which I own), Canon has managed to do so
    without degrading the image with more noise. My preference would
    have been to keep the A640 at 7mp and try to reduce the noise (ie,
    increase the usable ISO a notch or two). But other people might
    prefer the higher resolution. An alternative would be to check out
    the A630, the A640's smaller, less expensive 8mp sibling.
     
    ASAAR, Feb 8, 2007
    #10
  11. Thanks for the clarification.

    I guess it is hard to find some general rule of thumb about which
    sensor size can properly handle what level of megapixels.

    I guess I was hooping for something like this, for example:

    "An Oly 4/3rds sensor is large enough to properly resolve a full
    12 megapixels of image data - anything above that and you might
    start to lose detail because the sensor cannot properly
    accommodate more than 12 megapixels. In order to get higher than
    12 megapixels and have those extra pixels be meaningful, they
    would have to increase the size of the sensor"

    But I guess it isn't that simple.

    I do appreciate the reply. The more I read, the less that
    article seems to be on target. They generalized too much, I
    think.

    Canon certainly seems to feel that the sensor in their 10mp A640
    is fully capable of handling all 10mp of data properly, and
    Olympus seems to feel very confident that the size of its 4/3rd
    sensor is able to handle a full 8mp without any compromise in
    quality.

    Anyway, I'll keep on readin' - there is much to learn. :)

    > themselves unable to use them with the A640. The A640's 10mp
    > sensor won't have the resolution of a good 10mp DSLR, but the
    > resolution it does provide is probably about as good as the
    > resolution you'd get from other 10mp P&S cameras using the
    > same size sensor.


    > performance. The reviews indicate that even though more
    > pixels are squeezed into the same size sensor that is used by
    > the 7mp sensor in the A620 (which I own), Canon has managed to
    > do so without degrading the image with more noise.
     
    Paul D. Sullivan, Feb 8, 2007
    #11
  12. Paul D. Sullivan

    acl Guest

    On Feb 8, 11:48 am, "Paul D. Sullivan" <> wrote:
    > Thanks for the clarification.
    >
    > I guess it is hard to find some general rule of thumb about which
    > sensor size can properly handle what level of megapixels.
    >
    > I guess I was hooping for something like this, for example:
    >
    > "An Oly 4/3rds sensor is large enough to properly resolve a full
    > 12 megapixels of image data - anything above that and you might
    > start to lose detail because the sensor cannot properly
    > accommodate more than 12 megapixels. In order to get higher than
    > 12 megapixels and have those extra pixels be meaningful, they
    > would have to increase the size of the sensor"


    Well, the reason you don't get such an answer is probably that you
    haven't defined the question carefully enough. There's not much
    problem with these small sensors with lots of pixels, except for a)
    noise, b) high pixel density which means the lens needs to resolve
    many more line pairs/mm (at the sensor) than for eg a DSLR (which has
    much larger pixels). The second problem is alleviated by the fact that
    the sensor is smaller and thus the size of the image that must be
    projected by the lens is also smaller, so that the lens doesn't cost
    as much as one with equivalent resolution with a DSLR (or medium
    format back!). On the other hand, I would have thought that not all
    that much money and effort would be expended on making the lenses on
    these compacts as sharp etc as possible, so probably some degradation
    is also coming from there.

    So, one cannot say "a sensor of size m cannot properly accomodate more
    than n pixels", for the simple reason that you have not defined
    "properly". If you say eg "this amount of noise is acceptable", then
    probably a rough estimate can be found, or at least an upper limit for
    n. But how do you plan to quantify it? Better to look at images and
    decide.

    There's not much else wrong with small sensors beside this noise
    business (which can be a huge problem of course!), and of course there
    are several advantages (cheaper and smaller lenses and cameras,
    possiblity of having more versatile zooms with reasonable quality
    etc). But a 10mp camera with a small sensor (such as the various
    recent compacts) will always have more noise than a 10mp with a bigger
    sensor (at least if they are both newer than, say, 2004).

    >
    > But I guess it isn't that simple.
    >
    > I do appreciate the reply. The more I read, the less that
    > article seems to be on target. They generalized too much, I
    > think.
    >
    > Canon certainly seems to feel that the sensor in their 10mp A640
    > is fully capable of handling all 10mp of data properly, and
    > Olympus seems to feel very confident that the size of its 4/3rd
    > sensor is able to handle a full 8mp without any compromise in
    > quality.


    Well, as for handling the data, it's not a problem; the problem is to
    actually collect it. But clearly if Canon did feel that the sensor
    could handle 10mp with no problem, why do they produce cameras with
    bigger ones? Do you really think that people pay 6-7000 euro for a
    1Dmkwhateveritis just to be able to use their old lenses, if they
    could get similar results otherwise? The differences, when they are
    visible, can be huge, and so is the price difference!

    >
    > Anyway, I'll keep on readin' - there is much to learn. :)
    >
     
    acl, Feb 8, 2007
    #12
  13. On Feb 7, 8:46 am, "Paul D. Sullivan" <> wrote:
    > I read an article on Cnet about how 8 or 10 megapixel cameras are
    > not as good as they could be because their megapixel capability
    > does not match sensor sizes well. If you buy a camera with 8 or
    > 10 megapixels and they have some really small sensor, the extra
    > megapixels will not be realized in terms of quality.
    >
    > Got me thinking - what are some of the best matches of megapixel
    > capability to sensor size?
    >
    > How does the Canon a640 mentioned in the article hold up?
    >
    > How does the Canon S3 IS hold up?
    >
    > Olympus Evolt series with those 4/3rds sized sensors?
    >
    > Do Fuji, Kodak, Nikon and others have a good ratio on average, or
    > are certain models better than others?
    >
    > I'd like to think that consumers aren't getting screwed when they
    > want to get to an 8 or 10 megapixel camera, and wanted to ask
    > some of ya'all here about it so I could learn what up.
    >
    > Any helpful answers would be appreciated.
    >
    > Thanks




    It is the same situation as with film- "bigger is better". There used
    to be an old saying- "nothing beats format size". While sometimes
    people made higher acuity film for smaller formats, frequently the
    film would gravitate up to larger formats.

    With digicams bigger format size means larger aperture diameter at
    same f/#, and collecting more photons during the same exposure time
    period.

    More expensive, of course. Silicon chips are more expensive when
    larger, larger lenses needed for same field of view. But- better!
     
    Don Stauffer in Minnesota, Feb 8, 2007
    #13
  14. Paul D. Sullivan

    Bill Funk Guest

    On Thu, 08 Feb 2007 06:56:35 GMT, "Paul D. Sullivan"
    <> wrote:

    >But I guess I'd further ask, what megapixel size is that sensor
    >able to resolve properly? Is 8 mp a good fit for that 4/3rds
    >sensor? Would it max out at 8 mp or would it also work well for
    >10 mp or 12 mp too?


    I think you're asking for objective answers to subjective questions.
    How do you define "resolve properly"?
    What is a "good fit"?
    What does "work well" mean?

    The answers will differ depending on who's asked. The end result is
    that only you can answer these questions for yourself.
    There are sites (such as, for example, dpreview.com) that offer sample
    images from reviewed cameras, so that you can see for yourself how
    these various cameras handle different conditions.
    At such sites, you can see how well each camera handles the
    compromises between different design goals; is 10MP on this camera
    worth the trade-off in more noise? Or should you stick with the 8MP
    model?
    These are questions only you can answer; that's why there are so many
    different makes and models out there; they offer different
    combinations of compromises to attempt to meet the demands of as many
    users as possible. But they aqre all compromises; there is no perfect
    answer to your questions.

    --
    Massachusetts' former governor
    Mitt Romney said Tuesday he will
    announce his candidacy for the
    GOP nomination for president next
    week. He's a Mormon. It's not
    expected to hurt him as long as
    Rudy Giuliani is the candidate
    with three wives.
     
    Bill Funk, Feb 8, 2007
    #14
  15. Paul D. Sullivan wrote:
    > That's a ton of data that I can't begin to understand. I wonder
    > if you would be so kind as to help summarize it in simpler terms?
    >
    > For example, you indicate that the 4/3rds in the Oly Evolt is mid
    > range. That makes sense and I can understand that.
    >
    > But I guess I'd further ask, what megapixel size is that sensor
    > able to resolve properly? Is 8 mp a good fit for that 4/3rds
    > sensor? Would it max out at 8 mp or would it also work well for
    > 10 mp or 12 mp too?


    For each camera, first compute the pixel pitch. The pixel
    pitch gives the best indicator of the active area of each pixel.
    To compute pixel pitch, look up the size of the sensor
    in mm. Many cameras have only an obscure size related to
    vidicon vacuum tube size from over 50 years ago.
    Sensor size conversion is here:
    http://www.clarkvision.com/imagedetail/does.pixel.size.matter/index.html#Sensor Sizes

    Let's say your camera has a 1/2.5 inch sensor. The above table
    shows the real sensor size is 5.76 x 4.29 mm Now look up
    the maximum size of images (not interpolated digital zoom)
    the camera makes. For example the Canon S3 with a 1/2.5-inch sensor
    gets 2816 x 2112 pixels. Take the size in mm times 1000 divide by
    the number of pixels:

    pixel pitch = long dimension in mm * 1000 / #pixels in long dimension

    Canon S3 pixel pitch = 5.76 * 1000 / 2816 = 2.0 microns.

    (there are 1000 microns per mm; the reason for the 1000 factor).

    Now go to
    http://www.clarkvision.com/imagedetail/digital.sensor.performance.summary/index.html

    and plot a point in the gray band on Figure 2, 4 and 6 on the above
    web page to get an idea of the camera performance, and how it
    compares to other cameras. For example, on Figure 6, unity
    gain ISO, 2-microns plots around ISO 100 in the gray band, the
    bottom of performance. The unity gain ISO is the ISO where
    1 digital number corresponds to 1 electron, so using higher ISO
    is no help. This tells the high ISO performance of the camera.
    If, for example, you want to take pictures indoors without flash of moving
    subjects (baby's first step, kids and pets at play), you want unity gain
    ISO to be as high as possible, with ISO 400 being a point where
    images are reasonable quality (my opinion). In effect, ISO's higher
    than the unity gain ISO is like "digital ISO." "Digital ISO,"
    like digital zoom can be done in post processing and gains no
    additional real image information. Camera manufacturers should
    be able to publish unity gain ISOs on each camera in my
    opinion.

    Plotting points on Figure 2 will show image quality of a typical
    well-exposed scene. You want to be in the 40 to 1 range or higher.
    If the camera has ISO 50, the boost the numbers by 1.4x, so
    ISO 100 giving signal-to-noise ratio (S/N) = 30 would give
    30*1.4 = 42 at ISO 50 and good quality. If you do a lot of
    editing (stretching, dodging and burning), you need higher
    S/N. Also, if you want good shadow detail, you need good
    S/N.

    For total image quality, good lenses with high megapixel count
    using larger pixels are best, but that makes for a larger (bulk and
    weight) camera and higher cost. Only you can decide what
    trade point you want/can afford.

    Roger
    >
    > Thanks much. :)
    >
    >> While one can't prove there is an optimum, because the
    >> trade space of size of a pixel versus performance just keeps
    >> getting better with larger pixels, I personally think the
    >> about 6 to 8 micron pixel pitch is the ideal size. That pitch
    >> allows many pixels to be crammed into an small sensor
    >> (e.g. about 8 megapixels in APS-C), while still collecting
    >> enough photons for great performance, including high ISO
    >> performance. Collecting about 50,000 photons per pixel
    >> produces beautiful images, and the 6 to 6 micron pixel pitches
    >> do that. This is the performance point of many DSLRs.

    >
    >
     
    Roger N. Clark (change username to rnclark), Feb 9, 2007
    #15
  16. There is an easy way to calculate needed pixel pitch for
    a "quality" camera.

    That is to assume a "usual" f/number for the lens.

    Assume that it will be near diffraction limited at
    two stops or a little more from wide open. Calculate the
    pixel pitch needed to resolve this without aliasing.
    From that and the sensor size you get the needed
    number of pixels.

    Let's see .. assume an f/5.6 lens, and diffraction
    limited at f/8. Assume a sensor size of 200x250 mm
    ..... and calculate. Ummmmm ... yummy.

    Doug McDonald
     
    Doug McDonald, Feb 9, 2007
    #16
  17. Doug McDonald wrote:
    >
    > There is an easy way to calculate needed pixel pitch for
    > a "quality" camera.
    >
    > That is to assume a "usual" f/number for the lens.
    >
    > Assume that it will be near diffraction limited at
    > two stops or a little more from wide open. Calculate the
    > pixel pitch needed to resolve this without aliasing.
    > From that and the sensor size you get the needed
    > number of pixels.
    >
    > Let's see .. assume an f/5.6 lens, and diffraction
    > limited at f/8. Assume a sensor size of 200x250 mm
    > .... and calculate. Ummmmm ... yummy.


    You mean like this?
    http://www.clarkvision.com/photoinfo/large_mosaics

    Roger
     
    Roger N. Clark (change username to rnclark), Feb 10, 2007
    #17
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