[filmscanners] Re: over resolving scans

["Preston Earle" <PEarle@triad.rr.com>]

<focus@adnc.com> wrote: "Is 2700dpi "good enough" in many, many cases?
Sure. Do you lose anything from scanning at higher resolution? Nothing
except time and hard drive space. (Yes I've read Dan Margulis contrary
views on the subject - his arguement includes the idea that less
micro-detail sometimes looks better - obviously, if you agree with that
there IS a good case for lower resolution, although you can still do it
yourself better in Photoshop."
--------------

Isn't scanning resolution more a question of image and print size than
it is of image quality? As with film and negatives, in general the
larger the original, the larger a good print can be made. (Boy, that
sounds awkward--is its meaning clear?) If all I need are 4x6 prints, I
don't really need 2¼ film over 35mm. Similarly, if I  want 16x20 prints,
4x5 film is probably better than 2¼.

For digital images, I only need 1.5 to 2 pixels per output dot/spot for
most printing applications. A 2800dpi 35mm scan will produce up to
12"x18" prints under this rule-of-thumb.  Sure, with a 4000dpi scan I
could go to 18"x27", but if I'm not going to print larger than 12"x18",
why scan for higher resolution? If I need to crop an image, then the
higher resolution may be useful, but just to get more pixel values that
will to be averaged when the file is printed is wasteful of time, disk
space, and perhaps quality.

In the good old days of drum scanning, resolutions of up to 10,000 "dpi"
(or more precisely, scan-lines-per-inch) were available, but images were
scanned at a resolution to give 300ppi at the largest print-size
expected for the image. If you guessed wrong and needed the image
larger, you rescanned it. Every image wasn't scanned at 10,000 "dpi"
just because you could.

That being said, I've often wondered why drum scanners gave so much
better "unsharp masking" than Photoshop does. In the late 80's and early
90's my printing company had a DS608 scanner that produced absolutely
gorgeous, very "tight" dark/light halos around images that Photoshop has
never been able to match. Not being a scanner operator, I don't know why
this might be the case, but I have wondered if the secret involved
processing those very fine scan lines prior to converting to half-tone
dots.

Preston Earle
PEarle@triad.rr.com

And I still don't know nothing about no stinking dynamic range.

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