Highest useful ISO rating

Discussion in 'Digital Photography' started by Jack, Nov 30, 2004.

  1. Jack

    Jack Guest

    Greetings,

    The ISO rating of digital cameras (high end cameras) have an upper ISO
    rating that is remaining static at 3200. Is this an upper limit with the
    technology or is this upper limit really being dictated by the fact that
    above 3200 is not in demand and would not be used even if possible at
    acceptable low noise.
    I would be inclined to think that ISO 100,000! would be very disirable.
    Not much need for IS, flash, those heavy expensive fast lenses.
    Increasing ISO rating does not seem to be a priority right now with
    manufactures


    Jack
     
    Jack, Nov 30, 2004
    #1
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  2. "Jack" <> wrote in message
    news:...
    > Greetings,
    >
    > The ISO rating of digital cameras (high end cameras) have an upper ISO
    > rating that is remaining static at 3200. Is this an upper limit with the
    > technology or is this upper limit really being dictated by the fact that
    > above 3200 is not in demand and would not be used even if possible at
    > acceptable low noise.
    > I would be inclined to think that ISO 100,000! would be very disirable.
    > Not much need for IS, flash, those heavy expensive fast lenses.
    > Increasing ISO rating does not seem to be a priority right now with
    > manufactures


    ISO 6400 and higher would be very desirable if the noise was acceptable. As
    of now, it is not acceptable.
     
    Charles Schuler, Nov 30, 2004
    #2
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  3. Jack

    Stu Guest

    "Charles Schuler" <> wrote in message
    news:p...
    >
    > "Jack" <> wrote in message
    > news:...
    >> Greetings,
    >>
    >> The ISO rating of digital cameras (high end cameras) have an upper ISO
    >> rating that is remaining static at 3200. Is this an upper limit with
    >> the
    >> technology or is this upper limit really being dictated by the fact
    >> that
    >> above 3200 is not in demand and would not be used even if possible at
    >> acceptable low noise.
    >> I would be inclined to think that ISO 100,000! would be very disirable.
    >> Not much need for IS, flash, those heavy expensive fast lenses.
    >> Increasing ISO rating does not seem to be a priority right now with
    >> manufactures

    >
    > ISO 6400 and higher would be very desirable if the noise was acceptable.
    > As of now, it is not acceptable.
    >


    Suppose cameras would need to be super chilled to keep the noise down, but
    then I don't really know what I am on about, just thinking out aloud :)

    Stu
     
    Stu, Nov 30, 2004
    #3
  4. (Jack) wrote in
    news::

    > The ISO rating of digital cameras (high end cameras) have an upper
    > ISO rating that is remaining static at 3200. Is this an upper limit
    > with the technology or is this upper limit really being dictated by
    > the fact that above 3200 is not in demand and would not be used
    > even if possible at acceptable low noise.
    > I would be inclined to think that ISO 100,000! would be very
    > disirable. Not much need for IS, flash, those heavy expensive fast
    > lenses. Increasing ISO rating does not seem to be a priority right
    > now with manufactures


    You increase the ISO rating of a camera by increasing
    the amplification of the analog signal before doing
    A/D conversion. This increases the signal and the noise.
    Eventually, the noise will be more than can be tolerated
    in a photo. And if you amplify some more, there will
    almost only be noise. And if you amplify even more, you
    will not get enough photons per pixel to get any photo,
    even theoretically.

    ISO 3200 is useful for high end DSLRs today. You can also
    get one or two stops more by underexposing, using the exposure
    compensation setting. So ... you can expose at ISO 12800
    without using manual settings. The quality will undoubtly
    be bad - but sometimes it is better than movement blur.

    But - ISO 100,000? Nope - I don't even know if that is useful
    for a 6 Mpixel camera with regard to photon noise. Maybe for
    a 6 pixel camera :)


    /Roland
     
    Roland Karlsson, Nov 30, 2004
    #4

  5. > Suppose cameras would need to be super chilled to keep the noise down, but
    > then I don't really know what I am on about, just thinking out aloud :)


    Sure you do Stu! Cooling would help a lot. There might be a way to do it,
    too. There are semiconductor heat transfer devices based on the Peltier
    effect. http://www.digit-life.com/articles/peltiercoolers/

    Also, there is a lot of development room left in this field. For example,
    it might someday be possible to make high quality semiconducting crystals
    that are carbon based rather than silicon based. "We aint seen nothin yet!"
     
    Charles Schuler, Nov 30, 2004
    #5
  6. Jack

    Alan Meyer Guest

    "Charles Schuler" <> wrote in message
    news:...
    >
    > > Suppose cameras would need to be super chilled to keep the noise down,

    but
    > > then I don't really know what I am on about, just thinking out aloud :)

    >
    > Sure you do Stu! Cooling would help a lot. There might be a way to do

    it,
    > too. There are semiconductor heat transfer devices based on the Peltier
    > effect. http://www.digit-life.com/articles/peltiercoolers/
    >
    > Also, there is a lot of development room left in this field. For example,
    > it might someday be possible to make high quality semiconducting crystals
    > that are carbon based rather than silicon based. "We aint seen nothin

    yet!"

    I'm not an expert in this stuff, but I can imagine several current limits
    in signal amplification. Here are my speculations:

    Thermal noise is a big one. "Thermal noise" is random motion of
    electrons caused by heat. In a TV set, over amplified thermal
    noise is what is we call "snow" on the video screen. In a radio
    it's "static". I would think cooling would help.

    Another possible limitation is the sensitivity of the sensor. One
    photon may not make any impression at all on the sensor.
    I presume that for any sensor technology, there is some minimum
    amount of light needed to get a response, and some minimum
    increment of light to get a detectable increment in the response.

    Reciprocity may be a related issue. In film, cutting the light in
    half requires doubling the exposure time - up to a limit where
    reciprocity failure occurs. Beyond that point, cutting the light
    in half requires more than doubling the exposure time. I suspect
    there may be some similar phenomenon with sensors.

    But in spite of all that, I'd be very surprised if we were anywhere
    near ultimate physical limits in any of these areas. I bet there
    will be improvements in all of them over the years and we'll
    wind up with ISO values much better than film.

    As one piece of evidence for that, look at the LCD displays
    that "gain up". They show that the possibilities are there.

    Alan
     
    Alan Meyer, Dec 1, 2004
    #6
  7. Jack

    GTO Guest

    For a digital image sensor an ASA (or ISO) rating at 100k is not a problem.
    Because CCDs give a linear response over a large range of light intensities,
    these type of cameras can function as imaging spectrophotometers, producing
    tens to hundreds of times better resolution of light intensity than film
    cameras. Of course, Peltier cooling is required to suppress thermal noise.
    Sure, bias noise will have to filtered differently. But cameras for
    fluorescence microscopy and astronomy could be rated as such.

    With a Peltier cooler, one might even be able to push a DSLR to much higher
    ISO ratings.

    Gregor


    "Jack" <> wrote in message
    news:...
    > Greetings,
    >
    > The ISO rating of digital cameras (high end cameras) have an upper ISO
    > rating that is remaining static at 3200. Is this an upper limit with the
    > technology or is this upper limit really being dictated by the fact that
    > above 3200 is not in demand and would not be used even if possible at
    > acceptable low noise.
    > I would be inclined to think that ISO 100,000! would be very disirable.
    > Not much need for IS, flash, those heavy expensive fast lenses.
    > Increasing ISO rating does not seem to be a priority right now with
    > manufactures
    >
    >
    > Jack
     
    GTO, Dec 1, 2004
    #7
  8. Jack wrote:
    > Greetings,
    >
    > The ISO rating of digital cameras (high end cameras) have an upper
    > ISO rating that is remaining static at 3200. Is this an upper limit
    > with the technology or is this upper limit really being dictated by
    > the fact that above 3200 is not in demand and would not be used
    > even if possible at acceptable low noise.
    > I would be inclined to think that ISO 100,000! would be very
    > disirable. Not much need for IS, flash, those heavy expensive fast
    > lenses. Increasing ISO rating does not seem to be a priority right
    > now with manufactures


    I think it would require sensors with a larger pixel area, i.e. sensors in
    excess of the full-frame 35mm size. If you could get and afford an 8 x 10
    inch piece of silicon....

    David
     
    David J Taylor, Dec 1, 2004
    #8
  9. Jack

    Charlie Ih Guest

    If we use linear extrapolations (I believe it's valid) based on ISO = 100
    with a linear pixel size of 3.5 um, 100,000 is 1,000 times more
    sensitive. Thus to achieve ISO of 100,000, the linear pixel size should
    be about 100 um. So we can make a 2 MP camera with approx. 5"x 4"
    size sensor. However, normally manufacturers often over rate
    the ISO by a factor of 4, so we can make a 2 MP camera with ISO
    of 100,000 using a 2.5" x 2" sensor which is quite reasonable.
    So the camera can be made if there is enough market.


    In article <>,
    David J Taylor <> wrote:
    >Jack wrote:
    >> Greetings,
    >>
    >> The ISO rating of digital cameras (high end cameras) have an upper
    >> ISO rating that is remaining static at 3200. Is this an upper limit
    >> with the technology or is this upper limit really being dictated by
    >> the fact that above 3200 is not in demand and would not be used
    >> even if possible at acceptable low noise.
    >> I would be inclined to think that ISO 100,000! would be very
    >> disirable. Not much need for IS, flash, those heavy expensive fast
    >> lenses. Increasing ISO rating does not seem to be a priority right
    >> now with manufactures

    >
    >I think it would require sensors with a larger pixel area, i.e. sensors in
    >excess of the full-frame 35mm size. If you could get and afford an 8 x 10
    >inch piece of silicon....
    >
    >David
    >
    >
     
    Charlie Ih, Dec 1, 2004
    #9
  10. Jack

    Crownfield Guest

    David J Taylor wrote:

    > If you could get and afford an 8 x 10
    > inch piece of silicon....


    it would be cheaper
    to hire a full time four man team of assistants
    to carry flashes and lenses for you,
    and to set it all up for you.


    >
    > David
     
    Crownfield, Dec 1, 2004
    #10
  11. Jack

    Guest

    Jack <> wrote:
    > Greetings,


    > The ISO rating of digital cameras (high end cameras) have an upper ISO
    > rating that is remaining static at 3200. Is this an upper limit with the
    > technology or is this upper limit really being dictated by the fact that
    > above 3200 is not in demand and would not be used even if possible at
    > acceptable low noise.
    > I would be inclined to think that ISO 100,000! would be very disirable.
    > Not much need for IS, flash, those heavy expensive fast lenses.
    > Increasing ISO rating does not seem to be a priority right now with
    > manufactures


    The astronomers care a lot! The ultimate limit is a single photon,
    and the best CCDs approach that. But they use liquid nitrogen to do
    it, and the limits here are physical and quite fundamental.

    Some camera backs have active cooling, but there's a problem with
    condensation. You can partly solve that by using a fan.

    Andrew.
     
    , Dec 1, 2004
    #11
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