[filmscanners] Re: 3 year wait

["Op's" <martin@wollongong.apana.org.au>]

doogle@doogle.com wrote:

> Date sent:              Thu, 9 May 2002 15:06:35 -0400
> Send reply to:          filmscanners@halftone.co.uk
> From:                   "Austin Franklin" <darkroom@ix.netcom.com>
> To:                     doogle@doogle.com
> Subject:                [filmscanners] RE: 3 year wait
>
> >
> > > I run film recorder, and in those terms, the "general" resolving
> > > power of 35mm emulsions is referred to as "4K"...
> >
> > > "4K" is:
> > > 4096 x 2731 true pixels (apprx. 32MB TIFF file in 24bit, double
> > > that for 48bit) which
> > > 4000ppi at 36x24mm significantly exceeds.
> >
> > Mac,
> >
> > What you have described above is obviously 2700 PPI.
>
> Nope.
> 2700ppi does not achieve the 4K "standard".
> 2700ppi @ 36x24mm = 3827x2551
> It's in the neighborhood of the ballpark but not there, and is signifcant lack
>
> Can tell you that tests from my Lasergraphics Mark III DPM:
> a full frame 2700ppi scan back to film and projected side by side with film 
>original, I
> can certainly tell diff.

Yes I will agree with that.


>
> However, from drum scans I've had done at exactly 4096x2731, and also DOUBLE 
>that
> (which would be appropriate for 120 film output), the slides from recorder are
> indistinguishable from originals, with slight diffs in contrast/color 
>balance/levels due to
> scanning prefs and software tweaking, but *definition* wise, are identical. 
>And the
> kicker is, my recorder will do 8K rez also, and the large files show no 
>significant
> difference, so I'd say that 11-12MP of true pixel info IS pretty much what 
>(Ektachrome,
> at least) film can resolve.
>

My Polaroid  8K will do what ever resolution thats put into it (if its 6356x 
4539 then it will
print to that size) - and there is a difference over 4K but it has to be 
scanned higher to get
that result.


>
> 4k PPI for something
> > the size of a 35mm film gives you ~4k x ~6k, or 24M PIXELS, or 72M byte
> > files...as you say, significantly exceeds that...
>
> Actually 4000ppi is 21.4 megapixels, about 61.4 MB in Tiff, but who's 
>counting ? :-)
>
>
>
> Again, has to be true 4K rez from recorder. Models in the $5K range *do* scan 
>the
> requiste rez, but due to inferior flying spot mechanism, actually smear line 
>into line,
> giving much less effective rez.
>

I call that pixel overlap and this certainly unsharpens the image.  (or re 
smooths it after
digitising)


And yes 4K is close to what a film will resolve.

Rob

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