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Thread: DSLR Scanner: Lenses

  1. #91

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    Re: DSLR Scanner: Lenses

    Just an observation, not a criticism or anything... my biggest concern here is with stitching. As soon as you have the computer applying interpolation between two overlaid images, you're in the position of modifying the original scanned data - both deleting and recreating it, with added filtering in both linearly and possibly rotationally, depending where the software decides the overlay is and how well-designed the software algorithms are.

    While the intent is to extract the maximum detail from the scanned image, is fictional data around the joins necessarily the best way to achieve this?

    Neil

  2. #92

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    Aug 2015
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    Re: DSLR Scanner: Lenses

    I've had great success over the last year and a half using my Nikon D800E to scan all my slides and negs. Since I came to large format from predominantly shooting macro, I already had a pretty decent setup, which I've added to and adjusted over time.
    My basic setup of accessories: Gitzo 3540LS tripod with levelling base, Arca Cube geared pan head on Gitzo levelling base, Novoflex Castel-L macro rail, light panel.
    For digitizing 5x4 (5x4 crop-mode, stitch in photoshop of 4 frames) I use the Novoflex horizontally, and use my Nikkor 85mm PC-E with shift to achieve excellent results with the minimum of digital interference in the stitching process. (I just use books beneath the light panel to get the height about right, and use a bubble level on both the camera back and light panel to check levelling, and move the camera along the rail horizontally and shift the lens vertically up and down from centred on the middle of the slide to achieve the four frames to stitch). The film is held in place and flat on the light panel with a very rudimentary frame made out of some pieces of Lego.
    For 35mm (a single frame) and 120 (6x7, 2 frames stitched) I use my 60mm AF-S micro, attached to the Novoflex rail set vertically to work like a copy stand.
    With this setup I can get a 5x4 "scan" of slightly over 80mpx; the only limitation here really is the colour information the camera can catch (e.g. the colour separation between yellows and greens on a slide of Velvia 50). Not quite in the same ballpark as a drum scan, but I'm fairly confident that this would give an Epson scanner a very good run for the money, with almost certainly sharper results.

  3. #93
    Peter De Smidt's Avatar
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    Re: DSLR Scanner: Lenses

    Quote Originally Posted by barnacle View Post
    Just an observation, not a criticism or anything... my biggest concern here is with stitching. As soon as you have the computer applying interpolation between two overlaid images, you're in the position of modifying the original scanned data - both deleting and recreating it, with added filtering in both linearly and possibly rotationally, depending where the software decides the overlay is and how well-designed the software algorithms are.

    While the intent is to extract the maximum detail from the scanned image, is fictional data around the joins necessarily the best way to achieve this?

    Neil
    Neil, that's certainly a concern. I use a stitching template in PTgui for scans made with multiple captures. In practice I haven't seen a problem, but I haven't done extensive testing. For a small number of exposures, it's not hard to manually align the samples in Photoshop. Change the blending mode of the top layer to "Difference." Use arrow keys to nudge into place. Change blending mode to "normal"
    "Why can't we all just get along?" President Dale, Mars Attacks

  4. #94

    Re: DSLR Scanner: Lenses

    Neil, for capture methods such as an X Y stage and linear movement, the amount of invented (interpolated) data is probably far less than say when stitching conventional captures which are projected onto a 2D field from a spherical one like a panorama head would produce when rotated around a nodal point. Since with X/Y capture systems great pains are taken to align the image edge with the sensor edge and the stitching program is 'told' that a very long focal length lens is in use (I use 1000mm focal length), a nearly orthographic projection results from the captured images. This means that again, very little information needs guessing at in order to stitch images without visible seams.

    When I compare the results of my DSLR scanner to pano head stitches the results are night and day in terms of detail/sharpness. I'm not saying my film is resolving more, it isn't, just that the before and after results with film remain quite similar, not so with my digital captures.

    I once painstakingly captured a distant landscape with a Leica 50mm Summicron at f/8 on a D800E. Individually the captures left nothing to be desired. Once stitched and projected onto a flat field with a Sinc 256 algorithm in PTGui, the micro-contrast and stunning detail that was initially present had all but turned to relative mush. Quite disheartening indeed. So while your concerns are well founded, they have yet to rear their head in my X/Y capture system.

  5. #95

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    Re: DSLR Scanner: Lenses

    Excellent news, Daniel, and long may it continue.

    I guess I've been too long an engineer; I've seen most of the horrors that can happen once algorithms get in the act, and I tend to look at the bad effects first

    Neil

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