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How to scan a glass negative? - Adobe Photoshop 7, CS, CS2 & CS3

I have an old silver glass negative that I want to scan? Any advice? Do you know if a regular flatbed scanner will damage the negative? The size of the negative is 4x5 inches....

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  1. #1

    Default How to scan a glass negative?

    I have an old silver glass negative that I want to scan? Any advice? Do you know if a regular flatbed scanner will damage the negative? The size of the negative is 4x5 inches.
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    Bill_Brammer@adobeforums.com Guest

  2. #2

    Default Re: How to scan a glass negative?

    Is this a negative, or a tintype? The image on the latter is probably too
    light to scan.

    Any flatbed scanner with a transparency adapter should work. Resolution is
    not a major issue with 4x5 negatives because of its size. 300 dpi in the
    final print size is normally all that is required. An Epson 2450 (or 3200)
    would be an inexpensive choice of scanners.

    You don't want to put the emulsion in direct contact with the glass bed,
    because it might get scratched. Putting any flat surface in direct contact
    will also result in Newton's rings, which are hard to remove later. Make a
    mask which will support the negative at the edges, off the glass. Focus
    should not be a problem up to 0.5mm (1.5mm for the Epson 2450).

    Software is an issue. Epson software doesn't work well for
    photographic-quality scanning. Most people use SilverFast AI or Vuescan.

    Scan at full bit-depth, which is 14 bits/channel for the Epson 2450. 8-bit
    scans do not have sufficient resolution for B&W, and will look contrasty and
    posterized. It helps to combine multiple scans to reduce noise in the dense
    areas. SilverFast has a multiple-scan option.

    Some people have better luck scanning as a positive, then using Photoshop to
    invert the image. Scanning in RGB then converting to gray scale in Photoshop
    sometimes works better than scanning directly in gray scale.
    <com> wrote in message
    news:la2eafNXanI... 
    you know if a regular flatbed scanner will damage the negative? The size of
    the negative is 4x5 inches.


    Ed Guest

  3. #3

    Default Re: How to scan a glass negative?

    Bill,

    Any flatbed with a transparency adapter should be fine.


    LenHewitt@adobeforums.com Guest

  4. #4

    Default Re: How to scan a glass negative?

    What is a transparency adaptor?
    Bill_Brammer@adobeforums.com Guest

  5. #5

    Default Re: How to scan a glass negative?

    Additional light source from the top.
    And no, you can't very well "make" one.
    Turns off bottom light, only top one used.
    Sofware/firmware designed to work with it also, to calibrate
    exposure/color balance, reverse color negs to neutralize orange mask,
    etc.

    Mac
    Mac_McDougald@adobeforums.com Guest

  6. #6

    Default Re: How to scan a glass negative?

    Depending on the negative's density, you can sometimes get a useable scan on a standard flatbed scanner. Be sure to place the emulsion side of the negative facing the scanner glass. The worry I would have with a glass negative is that you might scratch the scanner glass.
    Another issue that crops up - even using a transparency adaptor - is the air gap between the two glass surfaces creating a moire pattern in the scan.
    There are various gooey or wet ways to fill the air gap and cure the moire problem, but I'm no expert in that area. Others here are more familiar with the procedure and will likely come forward.
    dennis_johnson@adobeforums.com Guest

  7. #7

    Default Re: How to scan a glass negative?

    Emulsion down, for better focus, then flop the image to make it right-reading. Try little shims at the edges, made of film or (maybe) tape, to very slightly separate the negative from the bed.
    r_harvey@adobeforums.com Guest

  8. #8

    Default Re: How to scan a glass negative?

    Dennis,

    The "air gap" shouldn't create a moire pattern. I would set the edges on thin cardboard to prevent contact with the glass as r_harvey has suggested.
    Photo_Help@adobeforums.com Guest

  9. #9

    Default Re: How to scan a glass negative?

    Glass plate negs are usually dense and sometimes contrasty. They are designed for printing with transmitted light, and if you try to scan as reflective copy, highlights will tend to block up. The tonal scale is also skewed. I have tried to scan my 8x10 negs that way, and even thin negs don't scan well.

    Better, make a contact print of the neg and scan that. Be sure that your print is fairly flat in scale. You can pick up contrast later. The print is an intermediary, so don't worry if it doesn't look good.
    Lawrence_Hudetz@adobeforums.com Guest

  10. #10

    Default Re: How to scan a glass negative?

    Photo Help,

    Moire patterns are indeed caused by the minute gap between the two surfaces. I called it an "air gap", but meant it in the sense that the gap is perhaps a few molecules of separation, and slight variances in the degree of contact between the two surfaces will cause the interference pattern to appear. If the gap is made larger, as by your technique, the interence patterns do not occur, but you run the risk of losing focus as the scanned element is her from the scanner surface. I don't know the focal depth of your scanner, but mine is limited.
    dennis_johnson@adobeforums.com Guest

  11. #11

    Default Re: How to scan a glass negative?

    And with moire in mind, do not make a glossy print!
    Lawrence_Hudetz@adobeforums.com Guest

  12. #12

    Default Re: How to scan a glass negative?

    dennis,

    You said it yourself. It is the contact interference, not the "air gap", that causes the pattern. Raising the negative a millimeter or two is not going to make a bit of difference with regard to the focal depth of the scanner.
    Photo_Help@adobeforums.com Guest

  13. #13

    Default Re: How to scan a glass negative?

    Not moire... the pattern from the thin "air gap" is referred to as "Newton Rings" and is, as suggested above, due to "thin film interference", where the two reflective surfaces (the bottom of the negative and the scanner glass) cancel out (nodal points) discreet wavelengths of light at particular gap widths. They are typically multicolored due to the different parts of the spectrum being cancelled out. The pattern one sees in an oil slick on water is just such a pattern.

    Scanner operators have been solving that problem 2 ways for years:

    1- Oil mounting

    2- Newton Ring powder which is incredibly finely ground glass which diffuses the pattern without harming the image.

    Or the wider air gap should work too...
    John_Slate@adobeforums.com Guest

  14. #14

    Default Re: How to scan a glass negative?

    Yeah...what he said!

    :-)
    dennis_johnson@adobeforums.com Guest

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