[filmscanners] RE: 3 year wait

["Kapetanakis, Constantine" <KAPETAC@polaroid.com>]

As far as i know, most modern films (last we measured was '98) will give you
an MTF of 20-40 % at 4000dpi. That means that in theory the film is capable
of more than 4000 dpi. However in practical terms that is not generally
true.
What enters into the picture is film grain or granularity. For all CN films,
granularity is not primarily caused by the size of the individual dye clouds
(in the range of 2-10 microns), but mainly by their random distribution in
the emulsion layer. The scanner of 4000dpi would just be able to resolve
individual dye clouds, but the graininess perceived by the human observer is
caused by much larger clusters of dye clouds which can also be resolved by
scanners of lower resolution such as the SprintScan 35 @ 2700dpi.
Our experience has been that even in a 4000dpi scan the granularity in the
scanned image will not be higher than the granularity in a photographic
print from the same negative, if the total magnification negative to
hardcopy is the same and the scanner does not add any significant noise.
Further magnifying of the scanned image will probably reveal both : dye
clouds and scanner pixels.

-----Original Message-----
From: Austin Franklin [mailto:darkroom@ix.netcom.com]
Sent: Friday, May 10, 2002 9:47 AM
To: KAPETAC@polaroid.com
Subject: [filmscanners] RE: 3 year wait


> I guess everything I have read
> leaves me unbelieving that low speed quality films, especially slide
> films, res out at 4000 dpi.

I scan at 5080, and my 160 and less films still have "more to go".  Drum
scans can be  higher resolution, and people who use them also say that they
are able to take advantage of the higher resolution.

It's also easy to see that there is "more to go" if you have the film
resolution charts.  Average "decent" film has a resolution of, say, around
125 lp/mm...which is 6350 somethings per inch.  The really good color films
are around 160+, which is 8128.

T-Max 100 and Fuji Neopan 100 (B&W) can give 200 lp/mm, which is over 10k.

Now, of course, to get the film to actually record NEAR that much, you need
almost ideal conditions, tripod, high shutter speed, no vibration etc., as
well as a lense that can accommodate that...but that's just for edge detail.
Still, tonality will be recorded, whether it's perfectly in focus or not...

BTW, slide films are not better than negative films.  Overall, negative
films still do have a slight edge, though slide films are far better than
they used to be.

Austin

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