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Thread: Does multi-scan really reduce noise?

  1. #11
    David J. Heinrich
    Join Date
    Oct 2008
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    575

    Re: Does multi-scan really reduce noise?

    Richard, I'd think they'd be more concerned with wanting to resolve down to the level of film grain ;-)

  2. #12

    Join Date
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    Re: Does multi-scan really reduce noise?

    Are we talking about multi-sampling or multi-passing? I thought that in multi-sampling, the CCD doesn't move but makes multiple exposures and the results are averaged to get rid of noise. In multi-passing, the CCD goes over the whole piece of film multiple times to try and extend the dynamic range. This can obviously make things blurry as it's hard to line up exactly on subsequent passes.

    I think it also depends on the scanner from what I recall of the vuescan manual online. Some scanners can't multi-sample in place; they can only make passes, while others can multi-sample in place.

    If the CCD is not moving but merely firing 4x or 16x or whatever, how would that make the resulting pixel blurry?

    Am I totally off base here? (it won't be the first nor the last time...)

    -Mark

  3. #13
    David J. Heinrich
    Join Date
    Oct 2008
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    575

    Re: Does multi-scan really reduce noise?

    Quote Originally Posted by Mark Hodos View Post
    Are we talking about multi-sampling or multi-passing? I thought that in multi-sampling, the CCD doesn't move but makes multiple exposures and the results are averaged to get rid of noise. In multi-passing, the CCD goes over the whole piece of film multiple times to try and extend the dynamic range. This can obviously make things blurry as it's hard to line up exactly on subsequent passes.

    I think it also depends on the scanner from what I recall of the vuescan manual online. Some scanners can't multi-sample in place; they can only make passes, while others can multi-sample in place.

    If the CCD is not moving but merely firing 4x or 16x or whatever, how would that make the resulting pixel blurry?

    Am I totally off base here? (it won't be the first nor the last time...)

    -Mark
    Mark, I'm not sure, but I think my Epson V700 does multi-sampling, where the CCD stays in place. See the example of 3x vs. 16x here. These were scanned at 6400 dpi, and are 100% crops. It seems to me there is absolutely no difference in the level of shadow noise, so the multi-sampling is hence useless.

    In those two, I'm strained to see any difference in sharpness, but I would suspect that multi-sampling can reduce sharpness by exposing the film to the lamp for much longer periods of time, hence possibly causing warping.

  4. #14

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    Re: Does multi-scan really reduce noise?

    Quote Originally Posted by dh003i View Post
    Mark, I'm not sure, but I think my Epson V700 does multi-sampling, where the CCD stays in place. See the example of 3x vs. 16x here. These were scanned at 6400 dpi, and are 100% crops. It seems to me there is absolutely no difference in the level of shadow noise, so the multi-sampling is hence useless.

    In those two, I'm strained to see any difference in sharpness, but I would suspect that multi-sampling can reduce sharpness by exposing the film to the lamp for much longer periods of time, hence possibly causing warping.
    yeah that makes sense. I also have a V700, and I've used the multi-pass for more dynamic range, but I kind of agree with you about the multi-sampling not making any difference from what I remember from last time I did a comparison. I leave it at 4x anyhow for psychological reasons

    As for blurriness, I guess sharpness could be lost from heat expansion / warping, I suppose. Scanning is crazy; you're damned if you do and damned if you don't.

    On my Nikon 9000, however, the multi-sampling does seem to help out (at 4x vs 1x), especially with things like Velvia 50 blacks. I can't tell 4x vs 16x but sometimes I do 16x anyhow if it's going to be printed big. I don't have an example right now as I did the compare when I first got the scanner then have been either 4x or 16x ever since. I haven't seen a loss of sharpness at 16x on the 9000, for what it's worth.

  5. #15

    Join Date
    Oct 2007
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    602

    Re: Does multi-scan really reduce noise?

    I shoot 8x10 but I'm thinking about switching to 5x7 for portable applications.

    I scan whatever people give me... I just did a 12,000 DPI scan from a Velvia 50 35mm slide. Oh yes, there was grain, but after digitally processing the image you would think it was medium format if you didn't know better.

    Cheers,
    Ed

    Quote Originally Posted by Richard M. Coda View Post
    I find it humorous that people using 8x10 cameras are concerned with grain

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