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Thread: Making a scanner with a DSLR

  1. #81

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    Re: Making a New Modern Drum Scanner

    Rick,

    With a 5D Mark II and a 1:1 magnification, you're capturing 4000 raw SPI. Perhaps more pertinently, you're capturing somewhere in the neighborhood of 60-70 lp/mm with good contrast, depending on lens. So you're essentially matching the Coolscan 9000, which rates around 67 lp/mm.

    BTW, 60 lp/mm requires 3048 SPI. I think your math is off somewhere. 1600 SPI is only enough to resolve 31.5 lp/mm, and that's in an ideal world.

    Anyway, given that color negative film doesn't have much contrast past 70 lp/mm and few LF lenses can achieve that, I'd say it's enough. But if it isn't, or you shoot fine grained B&W, just wait a year or two and upgrade the camera to eke out more resolution. That's the good thing about a generic rail system. Not good enough? Just wait five minutes.

    The Epson doesn't really compare. In no way does it deliver 2000 high contrast samples per inch. But even if it theoretically could, that only works out to 40 lp/mm. Scanning on my 4990, I maybe see 30-40 lp/mm, but they're very mushy low-contrast lines. After some very destructive sharpening, you can bring out that level of detail, but you'll bring out plenty of noise and sharpening artifacts as well.

  2. #82
    Mike Anderson's Avatar
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    Re: Making a New Modern Drum Scanner

    Quote Originally Posted by rdenney View Post
    ...
    Rick "thinking we might all have to construct such tools when the existing generation of scanners pass away" Denney
    You're not alone:

    http://theonlinephotographer.typepad...r-bridges.html

    ...Mike

  3. #83
    Kirk Gittings's Avatar
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    Re: Making a New Modern Drum Scanner

    Tlitody, That is a good question going forward from here possibly without film but doesn't address the issue looking back at (in my case) 40 years of 4x5-only a fraction of which has been scanned.

    Personally I think this is a idea with some potential usefullness as scanners fall by the technological wayside.
    Thanks,
    Kirk

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  4. #84
    Peter J. De Smidt's Avatar
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    Re: Making a New Modern Drum Scanner

    Quote Originally Posted by Ben Syverson View Post
    I still think it's a mistake to make the first version motorized. You undoubtedly WILL have stability, vibration and focus problems.
    I don't plan on making my first version motorized. For me, a setup that allows a decent and fast "scan" for a digital version of a contact sheet would be useful. It would also allow experimentation into hi-res options.

    Rick "thinking the concept needs proof before building a machine" Denney
    Absolutely right.

    I can test a Nikkor 55mm macro, a Nikkor 105mm AF micro, and an 80mm Rodenstock Rodagon F4 on a bellows. My tests will be limited by my ability to focus my camera at those magnifications. I've found that extreme magnifications are very difficult to focus.
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  5. #85

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    Re: Making a New Modern Drum Scanner

    Is the test target that was used for the scanner comparisons available?

  6. #86
    Peter J. De Smidt's Avatar
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    Re: Making a New Modern Drum Scanner

    Quote Originally Posted by tlitody View Post
    I have a really great idea. Why don't we just use a digital camera and cut out the film altogether. And there's this little thing called HDR which means we can get way more dynamic range than film anyway. And since we would be stitching the images of the film we can use the digital camera on a pano tripod head and stitch the images to get more resolution than even film could produce if we use the right lens and get it right.
    I do regularly use a digital camera, including HDR and multirow stitching. What I've found is that the stitching works really well for a distant subject, but if you're fairly close, and using a wide field of view, the distortion gets really nasty, and since the stretching is so extreme, the end resolution gets really low on the edges.

    I recently photographed a church interior, both with digital and with my 4x5. With my setup, the 4x5 has much more detail than my digital setup. Sure, there are much better digital systems available, but I can't afford them.
    "Nothing will ever be attempted, if all possible objections must be first overcome." -- Samuel Johnson
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  7. #87

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    Re: Making a New Modern Drum Scanner

    [QUOTE=tlitody;826564]Now let me see. We like to use film because of all the detail we can capture. And we like the grain in film. So now we are going to photograph the film with a digital camera which we don't like because it doesn't have grain and will not capture the grain in the film anyway, and then use the digital file to output digitally./QUOTE]

    This thread already had a buzzkill.

  8. #88

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    Re: Making a New Modern Drum Scanner

    The macro copy stand would need to beat the epson by a fair bit, say 3 times better or 7200 dpi.
    That is better than 50 megapix per sqaure inch.
    So you need more than four but not as many as 9 non overlapping images in the inch to better that resolution. What is the most affordable solution to get a shot of a third of an inch square area?

  9. #89

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    Re: Making a New Modern Drum Scanner

    tlitody's comments are a good but ultimately unfounded challenge to this idea. A good camera and 1:1 lens can reproduce grain and achieve a very faithful digital representation of the negative. It doesn't look "digital."

    If one-shot digital photography is good enough for your needs, then by all means, do it. However, as numerous tests have shown, you can capture much more detail and latitude in one shot with film.

    If you're shooting static interiors, digital HDR is a viable alternative. If you need to shoot people or landscape, you're dealing with a moving subject, and digital HDR becomes more problematic. Negative film gives you a one-shot "HDR" image, which really just means your highlight information isn't thrown away.

    And of course, with LF you have movements, unique lenses and the luxury of a large ground glass which makes for faster easier focusing.

    So all of the above gives an outline of the reasons to shoot and scan film.

  10. #90

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    Re: Making a New Modern Drum Scanner

    Quote Originally Posted by Kirk Gittings View Post
    Tlitody, That is a good question going forward from here possibly without film but doesn't address the issue looking back at (in my case) 40 years of 4x5-only a fraction of which has been scanned.

    Personally I think this is a idea with some potential usefullness as scanners fall by the technological wayside.
    OK rent or buy a better scanning back for your 4x5 camera. Mount your best 4x5 enlarging lens on your 4x5 and photograph you negs from a very bright light table in one go. I think the graphics repro industry have been doing this for some while. Art work is digitised in this way. I just think that we are trying to reinvent the wheel here.

    or

    ICG still make drum scanners last time I looked. So they are not cheap. So instead of investing your $1,000,000 dollars in R&D, why not just pool enough to buy a highend drum scanner, employ someone to do scanning and offer the service country wide and those that contributed to the scanner get cheap scans done. Problem solved.

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