# Re: Which scanners REALLY provide 36 bit output? HP?

From: Steffen Kluge (kluge@fujitsu.com.au)
Date: Sun Dec 10 2000 - 17:43:01 PST

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  On Sat, Dec 09, 2000 at 11:00:06AM +0800, Steve Underwood wrote:
  > > represent all the information possible. For 19th century photography I
  > > believe 1200 dpi comes very close to this.
  >
  > This is about the resolution of most modern emulsions (unless you are using
  > super slow specialist films). I doubt the 19th centruy emulsions have
  > anything like that resolution. 19th century lenses are incapable of
  > resolving this well, anyway. Such a high resolution would only make sense
  > when scanning documents, or maybe paintings.
  >
  > The resolution of most film images are much poorer than most people
  > realise.

  Well, all decent 100ASA slide or negative emulsions are capable
  of recording in excess of 100 lines/mm, at a contrast of
  1:1000. That would be 2500lpi. Good lenses can get across maybe
  about 1200~2000lpi. Keep in mind that the pixels in a film
  emulsion are scattered (and different in size), so you need a
  lot more pixels in an orderly rectangular grid to get the same
  visual resolution.

  Cheers
  Steffen.

      --
      Steffen Kluge <kluge@fujitsu.com.au>
      Fujitsu Australia Ltd
      Keywords: photography, Mozart, UNIX, Islay Malt, dark skies
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