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.
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.
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
? :-)
>
> Who, on earth, came up with a claim of calling something 2700PPI, "4k", and
> what film recorder is it that makes such a claim?
>
> Cripes, can there be more misinformation in an industry?
>
> Austin
Lasergraphics, Agfa, etc. The "4K standard" was there before film recorders
could
actually do it. Who formulated the math early on, I dunno, but as per testing
above, it
seems quite credible to me.
And, btw, 4K at the pixel dimensions stated above is over 11 million pixels.
I think that 11MP is the "holy grail" of digicam sensors to "equal" 35mm film
for most
all intents and purposes.
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.
Can certainly tell you though, that with testing back to film and projecting
side by side,
that 4096 x 2731, the "4K" film recording standard, is certainly quite close to
what
35mm E-6 and C-41 films can resolve.
Mac McDougald -- DOOGLE DIGITAL
500 Prestwick Ridge Way # 39 - Knoxville, TN 37919
doogle@doogle.com 865-540-1308
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