Higher dynamic range. Mfgs (except Fuji) ignoring it. Why?

Discussion in 'Fuji' started by RichA, Oct 14, 2006.

  1. Ben,
    I think that is a very neat idea. Alignment could be
    done in software pretty effectively. For most cases
    I think large pixel cameras with 16-bit A/D converters
    are the way to go, but for special applications, your
    idea is pretty cool. Why stop at 4 stops? Make it
    a 6 stop difference. A large pixel camera with an
    80,000 electron well and 4 electron read noise (14.3
    stops of dynamic range could be extended to more than
    20 stops). Of course some people will still complain that
    film is better. ;-)

    Roger N. Clark (change username to rnclark), Oct 16, 2006
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  2. RichA

    Mark² Guest

    Here's a link to my own results after conversion using the same test image
    that you sent to me some time back using CS2:

    Mark², Oct 16, 2006
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  3. As I understand it, they don't have a double amount of sensors,
    instead more like one third more: A "normal" Bayer sensor has
    a red, green and blue pixel. Fuji adds an "S" pixel, making groups
    of four from what used to be groups of three.
    Toni Nikkanen, Oct 16, 2006
  4. RichA

    Andrew Haley Guest

    Well, there are nearly 10 stops here, which might be getting close to
    the limit for real camera lenses. Multi-coating gets down to < 0.5%
    reflectance per surface, and there may be ten or more surfaces. The
    insides of a camera are all painted black, but there's still a
    significant reflectance; a few percent.

    Do you think, perhaps, that lens flare might limit true dynamic range
    before the limits of sensors are reached? [I presume that some
    astronomers know exactly what the practical limit of flare is for real
    lenses; I don't.]

    Andrew Haley, Oct 16, 2006
  5. RichA

    Scott W Guest

    Andrew Haley wrote:
    Whether the lens is the limit or not depends on the scene. Take an
    extreme case where you have a very small bright spot that only fills
    say 8 pixels on a 8 MP sensor. Even if you spread all of this light
    across the rest of the pixels it would only be 1/1,000,000 of the level
    that is hitting the 8 pixels, which would be close to 20 stops.

    Scott W, Oct 16, 2006
  6. Mark,
    I do remember this. If I remember correctly, you got that
    by tuning the converter for the shadows, and as a result
    compromising the highlights, correct? I was trying to
    get one overall best image with one conversion. After all
    the raw data information is there and it seems bizarre
    that going from 12-bit raw to 16-bit integers one would
    lose information. If I'm interpreting your example correctly,
    it shows that to get the full dynamic range with converters
    like the CS2 one, we must do two conversions, one for
    highlights, one for shadows, then blend the two. And
    that is what some people say they do.

    Roger N. Clark (change username to rnclark), Oct 17, 2006
  7. Scattered light in a lens system certainly limits dynamic range.
    But how much it limits depends on how close the bright subject is.
    Here is another test that shows just over 10 stops of dynamic
    See figure 6b. There are 6-stop changes in intensity that
    are close together. Of course, there might be greater
    ranges and lens flair reduced it to these levels.

    A more rigorous test here has 10 stops (verified) in one image:
    There are many very sharp boundaries, and little evidence
    for flair. When I get some time, I'll look into it more.
    Notice the slide film in figure 4 seems to show significant
    flair (scattering in the film, not the lens).

    Roger N. Clark (change username to rnclark), Oct 17, 2006
  8. Scott,
    That reminds me of astrophotos. Here is an astrophoto
    that has 4th magnitude stars that are overexposed:
    Very close to the brightest stars are measured nebulosity
    with brightnesses around 21 magnitudes/sq arc-second.
    Camera: canon 10D, 500 mm f/4 telephoto + 1.4x TC.
    That works out to 2.1 arc-seconds per pixel, so
    surface brightnesses are reduced by 1.6 magnitudes.
    Se we have a range of 21-1.6-4 = 15.4 stellar magnitudes,
    which is 2.512^15.4 = a dynamic range of 1,400,000
    or 20.4 stops. The dark sty is even darker, so
    a stop or so more.

    So the lens has flair (the stars are overexposed),
    but a short distance away, the flair is down by
    over 21 stops!

    Roger N. Clark (change username to rnclark), Oct 17, 2006
  9. RichA

    Mark² Guest

    My example (the top portion) was the result of a single CS2 conversion only.
    Mark², Oct 17, 2006
  10. Mark,
    So can you tell me the settings you used, and/or show
    the whole frame?

    Roger N. Clark (change username to rnclark), Oct 18, 2006
  11. RichA

    Mark² Guest

    I was trying to remember that... It's no longer fresh in my mind. I'll do
    some hunting on my computer and see if I can come up with the files, but I
    suspect that once I posted my result...I didn't keep everything. I'll

    Mark², Oct 18, 2006
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