Need high resolution scanner for unusual project

Discussion in 'Digital Photography' started by Mickey Schmidt via PhotoKB.com, Mar 17, 2005.

  1. I am a neophyte when it comes to scanners. Please help if you can. I have
    organized an engineering project at a military academy. It involves a very
    large lens (11" diameter, 160 degree field of view, f/2.8) The diameter of
    the image is 4.5". We will be photographing the night sky. Would like to be
    able to image stars. Although the main purpose may be to scan the sky for
    obscuring clouds for a large observatory.

    We are converting the lens to an all-sky camera. If I could afford it I
    would use a CCD and a precision scanning table and piece together the
    image. But as a class project I don't have that kind of budget.

    So I need some expert or at least experienced advice. Can a flat bed
    scanner be used to scan a focused image? If so what type of scanner has the
    highest resolution and the highest bit depth.

    I have seen a reference to grain reduction software how does this work.
    Please reply to this forum or directly to me at mickey.schmidt[at]usafa[dot]
    af[dot]mil

    Mickey Schmidt

    --
    Message posted via http://www.photokb.com
    Mickey Schmidt via PhotoKB.com, Mar 17, 2005
    #1
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  2. Mickey Schmidt via PhotoKB.com

    Scott W Guest

    You are going to have two problems, first when photographing the night
    sky the exposure times are normally in the many seconds to minutes, the
    scanner uses a very bright light source and scans at hundreds of lines
    per second, so you will simply not have enough light. The second
    problem that you will have is that you really need a field lens to make
    this work, a lens close to the focal plane that refocuses the light
    from the objective lens onto the imagine lens of the scanner, otherwise
    you will end up with a very small image circle. Putting in a field
    lens with out messing up the image is not easy.

    Scott
    Scott W, Mar 17, 2005
    #2
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  3. Considering who you are working for and where the school is located I would
    think that there would be observatories and government facilities that could
    help you. The might have some old stuff laying around. I wonder what night
    vision equipment might do. Bring the light in, boost it, and shoot the
    resulting green image.

    "Mickey Schmidt via PhotoKB.com" <> wrote in message
    news:...
    > I am a neophyte when it comes to scanners. Please help if you can. I have
    > organized an engineering project at a military academy. It involves a very
    > large lens (11" diameter, 160 degree field of view, f/2.8) The diameter of
    > the image is 4.5". We will be photographing the night sky. Would like to

    be
    > able to image stars. Although the main purpose may be to scan the sky for
    > obscuring clouds for a large observatory.
    >
    > We are converting the lens to an all-sky camera. If I could afford it I
    > would use a CCD and a precision scanning table and piece together the
    > image. But as a class project I don't have that kind of budget.
    >
    > So I need some expert or at least experienced advice. Can a flat bed
    > scanner be used to scan a focused image? If so what type of scanner has

    the
    > highest resolution and the highest bit depth.
    >
    > I have seen a reference to grain reduction software how does this work.
    > Please reply to this forum or directly to me at

    mickey.schmidt[at]usafa[dot]
    > af[dot]mil
    >
    > Mickey Schmidt
    >
    > --
    > Message posted via http://www.photokb.com
    Gene Palmiter, Mar 17, 2005
    #3
  4. "Mickey Schmidt via PhotoKB.com" <> writes:

    >So I need some expert or at least experienced advice. Can a flat bed
    >scanner be used to scan a focused image? If so what type of scanner has the
    >highest resolution and the highest bit depth.


    A normal flatbed cannot be used for this, because it has its own lens
    system that images the platen onto its CCD. To make it work, you'd need
    a rather strong large diameter field lens located near the scanner focal
    plane in order to redirect light from your prime lens into the scanner
    lens.

    However, there's another possibility: the Canon LiDE scanners do not use
    a conventional optical system. They have a sensor array that's actually
    8.5 inches long, and a lenslet array to transfer the image from paper to
    sensor at actual size. If you take one of these, disable the LED
    illumination, and remove the lenslet array, you have what amounts to a
    8.5x11 inch B&W scanning camera back.

    You'll still have angle of view issues (the sensor is at the bottom of a
    well, assuming that the light path is always perpendicular to the sensor
    plane, while your light will be arriving on various diagonal paths).
    But at least this is a plausible starting point.

    Dave
    Dave Martindale, Mar 18, 2005
    #4
  5. Mickey Schmidt via PhotoKB.com

    Rob Guest

    Mickey Schmidt via PhotoKB.com wrote:
    > I am a neophyte when it comes to scanners. Please help if you can. I have
    > organized an engineering project at a military academy. It involves a very
    > large lens (11" diameter, 160 degree field of view, f/2.8) The diameter of
    > the image is 4.5". We will be photographing the night sky. Would like to be
    > able to image stars. Although the main purpose may be to scan the sky for
    > obscuring clouds for a large observatory.
    >
    > We are converting the lens to an all-sky camera. If I could afford it I
    > would use a CCD and a precision scanning table and piece together the
    > image. But as a class project I don't have that kind of budget.
    >
    > So I need some expert or at least experienced advice. Can a flat bed
    > scanner be used to scan a focused image? If so what type of scanner has the
    > highest resolution and the highest bit depth.
    >
    > I have seen a reference to grain reduction software how does this work.
    > Please reply to this forum or directly to me at mickey.schmidt[at]usafa[dot]
    > af[dot]mil
    >
    > Mickey Schmidt
    >

    Have seen a one of those hand scanners which scans pages used as a
    panoramic camera. Think they actually altered the focal length to
    infinity and mounted it on a stepper motor. You may want to google up
    some more info.
    Rob, Mar 18, 2005
    #5
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