Re: Digicam

[SKID Photography <skid@xxxxxxxx>]

Kennedy,
But now we are getting into that whole theoretical detail from lenses and film vs.
the information contained in the grain, and the fact that the grain is both random
(fractal) in arrangement and form whereas pixel arrangements are in a grid.  So to
reproduce (in a scan) that random information, it takes a lot of rectangular
pixels.

Harvey Ferdschneider
partner, SKID Photography, NYC

> In article <3D02C440.ADAE8B1E@bway.net>, SKID Photography
> <skid@bway.net> writes
> >"Paul D. DeRocco" wrote:
> >
> >> Even with Kodachrome 25, a tripod, and a fixed focal length lens, I don't
> >> believe there's ever 8000dpi worth of actual picture information on a piece
> >> of film.
> >>
> >
> >Paul,
> >Then you would be wrong.  There is well over 40,000 dpi in a piece of 35 mm
> >film.   This has been discussed ad nauseum on several other lists and that has
> >been the conclusion, every time.   I don't wish to repeat it here.
> >
> Harvey,
>         whilst there may well be over 40,000dpi of information present
> on a frame of high resolution 35mm film, there certainly is not ever
> anything close to that in actual image information, which is what Paul
> was referring to.
>
> I suggest you take a look at some Kodak MTF curves for their colour
> films which generally show an MTF down to 10-15% at 120cy/mm maximum,
> falling at an order of magnitude every 10cy/mm or so.
>
> (E100S is at:
> http://www.kodak.com/global/en/professional/support/techPubs/e164/f002_02
> 17ac.gif )
>
> Kodachrome 25 was down to 10% MTF at 100cy/mm, E100S is 10% at only
> 70cy/mm.  A Fuji Provia 100F data sheet specifies the resolution at
> 1000:1 contrast (ie. much more than the typical fine detail in an image)
> of 140l/mm (probably meaning 140cy/mm, though) and only 60l/mm for a
> more typical 6:1 contrast object.
>
> Similarly, even a perfect f/8 lens has an MTF of only 50% at 100cy/mm
> and 10% at 200cy/mm, falling to zero at 250cy/mm (green light).
>
> Even assuming the best development, a high contrast object, the finest
> optical system possible and absolutely no camera motion during the
> exposure, the best we can realistically expect on the film is around
> 150cy/mm for the finest visually detectable detail.  Given the Nyquist
> sampling requirement of two pixels per cycle, this is 300pixels per
> millimeter, or approximately 7500dpi - at which level the detail will be
> no greater than the noise floor on even the best theoretical scanner!
>
> Yes, there may well be detail on film at 40kdpi, but it certainly ISN'T
> image detail!
> --
> Kennedy
> Yes, Socrates himself is particularly missed;
> A lovely little thinker, but a bugger when he's pissed.
> Python Philosophers
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