From: "George M. Anderson" <george@xxxxxxxxxxxxxxxxxx>
Pixels per inch is like film grain and again the bigger the number the
better. If you want to get a large (16x20 or better?) print from your
slide, you need the highest ppi you can get. To put things in
perspective though, if Kodachrome 25 resolves 100 lpmillimeter and your
lens can too, that's 25,400 ppi. So at 4000, you still aren't seeing
everything the film has to offer.
Math correction: 100 lines per millimeter is only 2540 lines per
inch. (25.4 mm = 1")
It takes two samples to resolve a line -- one to see the line, the
other to see the space between the lines, so that's only 1270 spi
(samples per inch).
Remember the factor of two whenever converting between lines and
samples/pixels/dots.
(And George, remember high school when they taught you the metric system? :-)
I don't want to get into a big discussion an what film resolution
really means in digital terms; I only wanted to correct the math.
Minolta Dimage: Anecdotal evidence is divided...
One list member who replied to my query
said he had one for a short time and got rid of it because of very poor
shadow detail...
I think that was me. I should qualify that statement: I think the
Minolta Dimage ScanDual does a great job for the money, and is
competitive with other 30 bit scanners in its price range. I found
all scanners in that price range lacking shadow detail, and replaced
it with one costing three times as much! For someone with only $500
to spend (or $300 used), I don't think the ScanDual is a bad choice.
It was a good "learning machine," but then I needed to move up from
the Pen F to the OM. (Obligatory Olympus content... :-)
If anything, I wanted to point out that range is more important that
pixels. The ScanDual at 2840? actually has more pixels than the Nikon
LS-2000. You're better off with a few good pixels, than tons of
garbage ones!
Nikon Coolscan LS200: Numbers: 36 bits; 2800 x 2800...
Actually, 2700 spi.
... The 2800
resolution, while better than most, would still be a problem if you want
to make big prints, as I do...
I actually don't see this as much of a problem. At 2700 spi, I'm
sampling the grain on any film over 100 ASA, and even on many slow
films. (As pointed out above, 100 lpmm isn't really that many
samples.) Careful up-sampling and sharpening in Photoshop can produce
very nice 11x17 prints. I have also had good luck using Genuine
Fractals to make extra pixels that look more natural than Photoshop's
bicubic interpolation.
If one's view of scanning is to print raw pixels, sure, get as many
as you can! But with some careful Photoshop work, I think you can
make presentable big prints from the ~9 Megapixels you get from a
2700 spi scanner.
: Jan Steinman <mailto:Jan@xxxxxxxxxxxxxx>
: Bytesmiths <http://www.bytesmiths.com>
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