The benefit of 7200 resolution for films scanning

Discussion in 'Film and Processing' started by alexandergusev, Aug 3, 2021.

  1. I scanned some black and white films with HP Scanjet 4600. The pointed resolution was 2400 dpi or Less . See samples. I want to make rescan with Primefilm 3650u or 7250u. There is essential price difference. So please write if there are any essential advantage in quality when scanning with 7250u for scanning of black and white films of bad quality.

  2. Format is important. For medium format roll film of low quality I can't see that it would make any difference. For 35mm in the hands of a competent amateur, the higher resolution would certainly be visible.
    alexandergusev likes this.
  3. For most 35mm films, including even Kodachrome, going beyond 9000 ppi brings no additional information.
  4. Is 9Kppi a typo? Or just a cynical comment?
    @alexandergusev Your attached image looks anything but sharp and could probably benefit from contrast adjustment for a rescan on your current machine.
    Do high resolution rescan, when you have a wonderful & perfect image ruined by pixelation. Otherwise: Either fix what you can or give up, due to "Garbage in, garbage out", which you can't change.
    alexandergusev likes this.
  5. I have posted on this many times.

    Scans at more than 9K pixels per inch resolve additional grain and dye cloud detail, not more image detail. I am talking about actual resolution not "interpolated" (which is useless) so-called 'detail'.

    The limit is that of the film itself, not the scanner nor the scanning technology.

    There are a very few ultra-hi-res films and special hi-res scanning, but these are not amateur equipment nor in the financial reach of most people, nor does this sort of thing help out with ordinary commercial films.

    I really am not being cynical, merely realistic.
    Last edited: Aug 3, 2021
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  6. Small (100%) crops of 200 ISO negative film scanned with a 3600ppi scanner and with various cameras at their maximum resolution.
    And the same section of negative comparing a dedicated film scanner (left) to a 10x print, flatbed scanned at 600ppi - effectively giving 6000ppi.

    Now here's an FP4 negative 'scanned' with a 24 megapixel camera at about 4x optical magnification - effectively giving a digital resolution of about 16,000 PPI.
    This shows that once the grain or dye-clouds are resolved, there's really no advantage in going to a higher resolution.

    However, the scanner or copying lens has to optically keep up with the digital resolution, otherwise a higher number of pixels is pointless. And since diffraction at f/5.6 or f/8 limits optical resolution to around 7000 and 5000 line-pairs per inch, respectively, it's highly unlikely that any affordable scanner gets anywhere close to optically resolving 7200ppi.

    IME anything over 4800ppi is either a waste of time or simply practically unobtainable.

    To sum up:
    • Your existing scan is definitely sub-par, since the film grain isn't resolved.
    • A Primefilm scanner will definitely improve on that.
    • Scanning at 7200 PPI is a waste of time, since it's probably an interpolated resolution anyway.
    FWIW. Scanner technology hasn't evolved at all in over 10 years, and the resolution is limited by the sensors available that are still being made (or old stock). Therefore any claims of resolution over 4000ppi are spurious hype.
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  7. Oh, BTW. Here's the full frame of the yacht sail crop shown above -
    alexandergusev likes this.
  8. I thank everybody for opinion.

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