Flat Bed Scanner + Enlarger = Film Scanner?

Discussion in 'Digital Photography' started by G. Huang, Jan 5, 2004.

  1. G. Huang

    G. Huang Guest

    I have a 6x6cm enlarger and an HP FB scanner. I am thinking of adding a
    switch to the scanner to turn off the light tube and use the enlarger to
    project the image on to the scanner. In theory, it should work, right?
    Before I risk trashing the scanner, I thought I should ask if anyone has
    done this before and what's the quality of the scan.
    I know there are MF film scanners but they are expensive and I won't use
    them enough to justify the expense.
    GH
     
    G. Huang, Jan 5, 2004
    #1
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  2. G. Huang

    Don Stauffer Guest

    I have a friend who did something very similar. He had an 8 x 10 view
    camera. Used the camera to project image on flatbed, scanned, and it
    worked great. I have seen the impressive images.

    This may only work on some scanners, but it will indeed work on some.


    "G. Huang" wrote:
    >
    > I have a 6x6cm enlarger and an HP FB scanner. I am thinking of adding a
    > switch to the scanner to turn off the light tube and use the enlarger to
    > project the image on to the scanner. In theory, it should work, right?
    > Before I risk trashing the scanner, I thought I should ask if anyone has
    > done this before and what's the quality of the scan.
    > I know there are MF film scanners but they are expensive and I won't use
    > them enough to justify the expense.
    > GH


    --
    Don Stauffer in Minnesota

    webpage- http://www.usfamily.net/web/stauffer
     
    Don Stauffer, Jan 5, 2004
    #2
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  3. G. Huang

    Jim Waggener Guest

    "> This may only work on some scanners, but it will indeed work on some.


    I love "Yogi-isms" ;-)




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    Jim Waggener, Jan 5, 2004
    #3
  4. G. Huang

    gsum Guest

    I tried exactly this with an old scanner and a 35mm
    enlarger recently but it didn't work. It could be made
    to work if you projected the image onto a fresnel
    lens on the scanner glass but it would be difficult
    to remove the hangover of fresnel rings from the
    image.

    The idea that flatbeds cannot give good results with
    film has been overtaken by technology. Modern
    flatbeds such as the Epson 3200 are not far behind
    dedicated film scanners for 1/10th the price. A new
    Epson is imminent. These scanners have masks for
    35mm, MF and 4x5 film.

    Graham


    "G. Huang" <-labs.com> wrote in message
    news:-labs.com...
    > I have a 6x6cm enlarger and an HP FB scanner. I am thinking of adding a
    > switch to the scanner to turn off the light tube and use the enlarger to
    > project the image on to the scanner. In theory, it should work, right?
    > Before I risk trashing the scanner, I thought I should ask if anyone has
    > done this before and what's the quality of the scan.
    > I know there are MF film scanners but they are expensive and I won't use
    > them enough to justify the expense.
    > GH
    >
     
    gsum, Jan 5, 2004
    #4
  5. G. Huang

    Dan Sullivan Guest

    "Jim Waggener" <> wrote in message
    news:...
    >
    > "> This may only work on some scanners, but it will indeed work on some.
    >
    >
    > I love "Yogi-isms" ;-)


    Me too.

    Yogi was being interviewed by Bryant Gumble.

    Bryant asked Yogi to try some word association.

    Meaning Bryant says something and Yogi says the first thing that comes to
    his head.

    Bryant said "Mickey Mantle."

    Yogi replied "What about him?"

    :-DDDDD

    Best, Dan
     
    Dan Sullivan, Jan 5, 2004
    #5
  6. "G. Huang" <-labs.com> wrote in message
    news:-labs.com...
    > I have a 6x6cm enlarger and an HP FB scanner. I am thinking of adding a
    > switch to the scanner to turn off the light tube and use the enlarger to
    > project the image on to the scanner. In theory, it should work, right?


    Two points to consider.
    1. The flatbed is (approximately) focused on the glass surface plane. You
    would probably need a means to focus the enlarger image on the CCD (remove
    scanner lens).
    2. The light source of the scanner is concentrated on a narrow line across
    the bed, in order to keep exposure time low (not all scanners allow the
    scan software to change exposure time). That light slit moves with the
    scanner head. A stationary lightsource will have significant light
    fall-off away from the center.

    Bart
     
    Bart van der Wolf, Jan 5, 2004
    #6
  7. "G. Huang" <-labs.com> writes:
    >I have a 6x6cm enlarger and an HP FB scanner. I am thinking of adding a
    >switch to the scanner to turn off the light tube and use the enlarger to
    >project the image on to the scanner. In theory, it should work, right?
    >Before I risk trashing the scanner, I thought I should ask if anyone has
    >done this before and what's the quality of the scan.


    You'll get severe vignetting with a standard scanner. The problem is
    getting the light that leaves the enlarger lens to enter the scanner
    lens anywhere other than near the centre of the image.

    Draw the light path for an an enlarger. Light from the enlarging lens
    reaches the paper at an angle to the vertical, except at the very centre
    of the image. That's fine for enlarging, because the paper doesn't care
    what angle the light reaches it from (within reason).

    Now look at the light path for a scanner. Although the path is folded
    several times by mirrors to keep the scan head relatively small, the
    optical path is equivalent to having a lens something like 10 inches
    below the glass surface, looking up at the glass through a narrow slit.
    At the edges of the page, the light has to leave the paper at an angle
    in order to enter the scanner lens. This isn't a problem when scanning,
    since the light illuminates the paper and the paper scatters the light
    in all directions.

    If you put a scanner under an enlarger, you need some way to bend the
    light from the enlarger lens, which is spreading out, back towards the
    scanner lens. As someone else suggested, a Fresnel lens of just the
    right focal length would work, but if the Fresnel lens is too close to
    the focal plane you'll see the rings. A large plain lens would work
    too, but the diameter needs to be larger than the area of the scanner
    platen you are using, and it needs to be fairly strong.

    There is one type of scanner that can be made to work. The Canon LiDE
    scanners don't use a small CCD plus a lens to capture the image, they
    use a large CMOS sensor that's the full width of the page, plus a long
    array of tiny lenslets to project the paper image onto the sensor. If
    you remove the lenslet array completely, you can project the enlarger
    image *directly* onto the CMOS sensor. Since there's only one lens
    involved (in the enlarger), you don't need to worry about redirecting
    light from one lens into the other.

    However, there's now another problem: the Canon sensor is B&W, and
    colour sensing is done by using red, green, and blue LEDs in sequence to
    illuminate the paper. If you're going to use an enlarger as the image
    source, you need to disable the scanner light source, but rapidly switch
    between red, green, and blue light in the enlarger in sync with the
    colour that the scanner believes it has turned on. A conventional
    enlarger won't do this; an enlarger head with R, G, and B strobe tubes
    might be able to, or you could use a rapidly-rotating colour wheel
    synced to the scan head. Or you could just make 3 greyscale scans with
    a colour wheel selecting red, green, and blue filters one for each pass.

    In short, an interesting experiment, but a lot of work for what you'd
    get.

    Dave
     
    Dave Martindale, Jan 5, 2004
    #7
  8. G. Huang

    G. Huang Guest

    Thanks for the explanation. I didn't know a scanners uses a lens and a
    small CCD array. I just checked my scanner and it does have a lens. I
    always thought all scaners use contact image sensors (close to your
    Canon example), but with 3 rows to get RGB.
    GH
     
    G. Huang, Jan 5, 2004
    #8
  9. "G. Huang" <gang@removethis_bell-labs.com> writes:
    >Thanks for the explanation. I didn't know a scanners uses a lens and a
    >small CCD array. I just checked my scanner and it does have a lens. I
    >always thought all scaners use contact image sensors (close to your
    >Canon example), but with 3 rows to get RGB.


    There seem to be several different arrangements. Most flatbeds use a
    small CCD trilinear array (3 rows of sensors, with red, green, and blue
    stripe filters in front) and white light illumination. The Canon CIS
    scanners are full-width sensor (probably CMOS) with a very interesting
    lenslet array and colour LED illumination for colour separation. The
    lenslet array appears to be GRIN lenses, which produce an *upright*
    image not an inverted one. (That's necessary for all the individual
    images to overlap to form a single image).

    Some film scanners seem to have a trilinear array and white light, while
    Canon seems to use a single-row small sensor and multiplex between 4
    light sources (RGB and infrared). In most modes the LS2000 (at least)
    moves the light source and lens/CCD while leaving the film stationary,
    but there's a preview mode that moves the film past a presumably
    stationary scanning head.

    Dave
     
    Dave Martindale, Jan 6, 2004
    #9
  10. G. Huang

    Rafe B. Guest

    On 6 Jan 2004 07:21:06 GMT, (Dave Martindale) wrote:

    >"G. Huang" <gang@removethis_bell-labs.com> writes:
    >>Thanks for the explanation. I didn't know a scanners uses a lens and a
    >>small CCD array. I just checked my scanner and it does have a lens. I
    >>always thought all scaners use contact image sensors (close to your
    >>Canon example), but with 3 rows to get RGB.

    >
    >There seem to be several different arrangements. Most flatbeds use a
    >small CCD trilinear array (3 rows of sensors, with red, green, and blue
    >stripe filters in front) and white light illumination. The Canon CIS
    >scanners are full-width sensor (probably CMOS) with a very interesting
    >lenslet array and colour LED illumination for colour separation. The
    >lenslet array appears to be GRIN lenses, which produce an *upright*
    >image not an inverted one. (That's necessary for all the individual
    >images to overlap to form a single image).
    >
    >Some film scanners seem to have a trilinear array and white light, while
    >Canon seems to use a single-row small sensor and multiplex between 4
    >light sources (RGB and infrared). In most modes the LS2000 (at least)
    >moves the light source and lens/CCD while leaving the film stationary,
    >but there's a preview mode that moves the film past a presumably
    >stationary scanning head.



    Yes, you'd need a scanner with a CIS (contact image sensor)
    array, rather than the more usual CCD+mirrors+lens array.

    However, I know of no CIS array that has sufficient resolution
    to come anywhere close to film's capability -- the best I know
    of are around 1200 dpi.

    CIS arrays are usually built with an integrated R/G/B LED
    lighting system.


    rafe b.
    http://www.terrapinphoto.com
     
    Rafe B., Jan 6, 2004
    #10
  11. G. Huang

    ONiLX

    Joined:
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    Location:
    Tokyo
    ONiLX, Aug 7, 2011
    #11
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