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Thread: CCD vs 35mm

  1. #11
    Roger Hamlett's Avatar
    Roger Hamlett Guest

    Default CCD vs 35mm

    "Tim Killian" <> wrote in message
    Not at the high sensitivities used for most astronomy imaging. The
    normally quoted equivalence point, for any but special fine grained
    emulsions, is about 18 million pixels, and for high sensitivity films it
    is around 5 million pixels. CCD's have about 10* the sensitivity managed
    by the best photographic emulsions, and retain their full resolution at
    these sensitivities. The 75 million pixel figure, is for a Bayer matrix
    based colour camera, in the 'worst case' condition for the Bayer matrix
    system, when compared to the best fine emulsions, that are being
    professionally processed. For most real world applications digital CCD's
    already match film, and for astronomy, they easily better it.

    Best Wishes

  2. #12
    Chris L Peterson's Avatar
    Chris L Peterson Guest

    Default CCD vs 35mm

    On Wed, 16 Feb 2005 13:39:35 -0700, Tim Killian <>

    300 lines per mm? Not even close. 35mm color emulsions like Provia and
    Sensia have spatial pixel equivalents of 5-10 MP, and lower overall
    information content than similarly sized CCDs because of the low dynamic
    range of those equivalent pixels. It is difficult to figure what an
    equivalent pixel actually is for film, because the MTF is so distorted
    (just a few line pairs per mm at one end), and because of the way light
    scatters in the emulsion. My measurements show that it is pretty fair to
    define a 10-bit deep pixel equivalent of color film at about 15 microns
    width. Tech Pan is better, but is on its way out.

    Certainly, an image with my 6MP digital contains visibly more detail
    than a professionally scanned 35mm Provia image made with the same lens,
    and produces higher quality enlargements (at 24"x36").

    In short, the spatial resolution of typical CCDs (with 6-9u pixels) is
    higher than film. The area of most sensors is less than that of 35mm
    film, but that situation is changing fast.


    Chris L Peterson
    Cloudbait Observatory

  3. #13
    Tim Killian's Avatar
    Tim Killian Guest

    Default CCD vs 35mm

    No, 100 lines/mm is what I suggested -- the 75 MP number is for a
    _color_ sensor (the kind normal people purchase) with three pixels under
    color filters for each image element. And if you actually think a 6 MP
    digital camera can produce a 24X36 enlargement with more detail than a
    good 35 mm film shot, you must be spending your time looking into GLPs.

    Here is a general, somewhat impartial analysis of film vs. digital:

    No real surprises here as the reciprocity failure of film shows up
    clearly. He puts the two formats to a real world test in:

    Film beats digital by a factor of 2:1 in resolution, even after scanning
    and digitizing. As technology advances, this will change, but for now,
    film still offers superior resolution compared to digital sensors.

    The issue of pixel size for CMOS sensors is crucial as well. Noise in
    CMOS is directly proportional to areal size for pixels and when this is
    combined with the conflicting need to maximize S/N with larger pixels,
    the result is an optimum pixel size for CMOS sensors in the 6-9 micron
    range. With these tiny pixels, dust on the sensor is a limiting factor
    and necessitates some kind of post processing gimmick if we expect
    decent enlargements.

    Chris L Peterson wrote:

  4. #14
    Martin Brown's Avatar
    Martin Brown Guest

    Default CCD vs 35mm

    Tim Killian wrote:

    It also shows that for most films at 100ASA and above that 6Mpixel
    digital cameras are superior in resolution.

    One particular film, Fuji Velvia, beats 6Mpixel digital at 35mm format.
    Go to 6x6 or half plate formats and film wins hands down. But with the
    exception of one very high definition slow emulsion modern digital
    cameras have reached a point where they are roughly equivalent to film
    in the 35mm format.

    Speciallised microfiche film would be off scale in terms of resolution,
    but you need the right equipment to use it.

    NB with Velvia at 50ASA you often need a tripod to be able to exploit
    the higher resolution - otherwise camera shake affects it. Push the
    processing and you lose some resolution. There are no free lunches.

    Martin Brown

  5. #15
    andrea tasselli's Avatar
    andrea tasselli Guest

    Default CCD vs 35mm

    Tim Killian <> wrote in message news:<>...

    He is comparing 4000 dpi scanned film with a D60 (no longer in
    production since a while and not a very good example of difital
    sensors to be fair) .jpg file???

    Can you show us how much better (if any) is any film (including TP)
    wrt CCD sensors in real world situations, especially in amateur
    astronomy? I'm all eyes...

    I'm struggling to see where/how dust is going to be a limiting

    Andrea T.

  6. #16
    Howard Lester's Avatar
    Howard Lester Guest

    Default CCD vs 35mm

    "Martin Brown"

    When they get to the equivalent of 6x7 cm, let me know. *yawn*

  7. #17
    Chris L Peterson's Avatar
    Chris L Peterson Guest

    Default CCD vs 35mm

    On Wed, 16 Feb 2005 23:10:56 -0700, Tim Killian <>

    Good luck finding a film that will give 100 lp/mm over a wide contrast

    I know this. I've spent a very large amount of time taking test images
    with film and various digital sensors, so I know very precisely what
    many films are capable of. I also have examples of images blown up to
    24x36, where the source material was made at the same time, same object,
    same optics. Without a doubt the 6MP digital images are sharper.

    My data suggests otherwise. For instance, I find that the actual
    information content of Provia and Velvia (the two emulsions I've looked
    most closely at recently) are quite similar. His test charts look
    somewhat different from my own, too. This sort of testing is very
    unrepresentative of the real world (unless, perhaps, you are a
    photographer specializing in picket fences <g>). Look at the MTF for
    film, and you see where these high contrast test targets fall apart. At
    one end of the contrast range, many films have effective pixel sizes
    somewhat better than typical CCDs. At the other end, however, they have
    equivalent pixel sizes that are a good fraction of a millimeter.

    No different from dust on film. Indeed, far more processing is required
    of film images to get rid of the myriad defects that can't be avoided.


    Chris L Peterson
    Cloudbait Observatory

  8. #18
    Mark S. Holden's Avatar
    Mark S. Holden Guest

    Default CCD vs 35mm

    Tim Killian wrote:

    I don't think you'll find many lenses that can reliably deliver 100 lines per mm
    on film.

    The Questar 700 F8 lens Modern Photography tested measured 64 lines/mm in the
    center, and 60 at the corners.

    I haven't seen similar lens tests for current mirror lenses, but I'd expect the
    Questar would still be considered exceptionally good.

    The mono cameras with the filter wheels do seem to provide more stunning images
    than something like my D70, but I'll take my D70 with noise reduction turned on
    over my film cameras for astro photography any day.

  9. #19
    RichA's Avatar
    RichA Guest

    Default CCD vs 35mm

    On Tue, 15 Feb 2005 20:12:15 -0600, "Brian Hill" <>

    Well, I don't know about 35mm, but the U-2 spyplane program still uses
    film because the team says digital is not as good for revealing

  10. #20
    Brian Hill's Avatar
    Brian Hill Guest

    Default CCD vs 35mm

    "Brian Hill" <> wrote in message

    Thanks guys for your very informative feedback. I can see the benafits of
    CCD imaging as far as conveinance and manipulation of the image and I'm sure
    I'll head in that direction. If I reading you guys right, it sounds like we
    might be spliting hairs as far as the resolution comparisons of CCD vs 35mm
    go unless one plans on making big enlargements? Is this a fair usumption?



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