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Thread: DIY DSLR Scanner vs Drum Scanner

  1. #31
    Still Developing
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    Re: DIY DSLR Scanner vs Drum Scanner

    Quote Originally Posted by Peter J. De Smidt View Post
    Hi Tim,

    Thanks for chiming in!

    You're comments are spot on. The Stouffer step wedge was photographed with a 40 year old lens and without a lens shade, but even a modern lens with an application specific lens shade there will still be some flare.

    I have a Cezanne, and I agree that scanning at a high resolution, approximately 6000 spi, gives very smooth scans with regards to grain.

    Daniel and I haven't done much with the dslr scanners lately, as that's more of a winter activity. After some refinements, we'd be happy to scan some negatives and then send them off to you for a comparison.
    Sounds good - I can send you a couple to scan as well (from the Big Camera Comparison test we did)

    It seems flare is inevitable - clear parts of the film itself diffuse light slightly and hence cause a 'glow' around dark edges. You get the same with flat bed scanners too (but only in one dimension). My Fuji Lanovia is stunning at getting shadow detail out of chromes but ruined by flare causing variations in dmax across a frame that are really hard to even out.

    Tim
    Still Developing at http://www.timparkin.co.uk and scanning at http://cheapdrumscanning.com

  2. #32
    Kirk Gittings's Avatar
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    Re: DIY DSLR Scanner vs Drum Scanner

    Thanks,
    Kirk

    at age 67
    "The woods are lovely, dark and deep,
    But I have promises to keep,
    And miles to go before I sleep,
    And miles to go before I sleep"

  3. #33

    Re: DIY DSLR Scanner vs Drum Scanner

    Is anyone making, or planning to make drum scanners?

    Imagine. A digital capture device using a shifting sensor to deal with the interpolation required by Bayer sensors.
    Thank you, Peter for sharing this (albeit rumored):

    http://www.dpreview.com/articles/232...g-sensor-shift

    Time marches on.

    What's next.

    And yes, I'm making assumptions, but you can bet they're coming, can't you. - Improvements. They're coming.

  4. #34

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    Reducing flare? Re: DIY DSLR Scanner vs Drum Scanner

    Quote Originally Posted by timparkin View Post
    Sounds good - I can send you a couple to scan as well (from the Big Camera Comparison test we did)

    It seems flare is inevitable - clear parts of the film itself diffuse light slightly and hence cause a 'glow' around dark edges. You get the same with flat bed scanners too (but only in one dimension). My Fuji Lanovia is stunning at getting shadow detail out of chromes but ruined by flare causing variations in dmax across a frame that are really hard to even out.

    Tim
    What if the light is polarized? Would you get less flare in one direction? With a flatbed you can scan textured photographs twice, rotating 90 degrees between scans, and sum the images in Photoshop, knocking out the differences. If we got less flare in one direction, the same technique could be employed, yes?

  5. #35
    Peter De Smidt's Avatar
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    Re: DIY DSLR Scanner vs Drum Scanner

    Interesting idea, Will.
    "Why can't we all just get along?" President Dale, Mars Attacks

  6. #36

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    Re: DIY DSLR Scanner vs Drum Scanner

    Thanks, Peter!

  7. #37

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    Re: DIY DSLR Scanner vs Drum Scanner

    I know, onnect17s remark (in post 10) about barrel distortion is some months ago, but maybe this is interesting as well.

    Adobe Lightroom offers a very good barresl distorsion correction and also correction of light fall off to the corners. It's available for all "known" lenses, but you can also create your own correction profiles with their software: http://www.adobe.com/support/downloa...jsp?ftpID=5490

  8. #38

    Re: DIY DSLR Scanner vs Drum Scanner

    That would be helpful for single captures.

    As for captures intended for stitching, distortion is actually not an issue since the very act of stitching requires that the lens distortion be characterized. In essence each time control points are generated these factors are determined and accounted for in order to be able to stitch them. Algorithms handle the vignetting or every stitch made would look ghastly. Where there are not enough details to allow for this profiling (large expanse of sky for example) a template can be use with known valid data from a previously saved, highly detailed stitch solution.

    The lenses Peter and I are using are of very high quality and I have not seen any chromatic aberration. Even if there were some it can be dealt with in the Raw processing stage by many converters. It's possible that stitching programs can handle CA as well but I would prefer to handle it at the Raw stage if present.

  9. #39

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    Re: DIY DSLR Scanner vs Drum Scanner

    I see, sound's reasonable. Otherwise one would need to "fix" the images on every panorama and the like...

  10. #40

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    Re: DIY DSLR Scanner vs Drum Scanner

    Ideally the size of the grain cloud times reproduction ratio should equal the sensor size. Multshot cameras should be good as it gets rid of the bayer grid issue and you can sub sample between the pixels which helps due to the stochastic nature of film. I could see a bayer grid causing issues. If your magnification ratio is too high for the film/sensor then you can get grain aliasing. Grain aliasing can be removed digital by programs like noise where however this negates the benefit to the increased resolution unless the resolution is many times higher then the grain clump so that the clump appears more like a halftone pattern in need of descreening. With negative film grain aliasing and natural noise/grain can be extenuated taking a small section of the cameras raw histogram and expanding it so much. This causes a combed histogram and can posterize the grain or noise.

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