On Fri, 7 Dec 2001 17:53:50 -0000 Jawed Ashraf
(Jawed@cupidity.force9.co.uk) wrote:
> Dare I say it, but the mistake here might be the belief that a 4000dpi
> scanner is actually capable of 4000dpi scans (or "samples per inch", if
> we
> want to reduce confusion).
>
> Anyone got any hard evidence of the *actual* resolving power of these
> scanners?
Objectively measured? No. AIUI it's pretty hard (ie expensive) to achieve,
as conventional test target images don't work properly with digital
systems. In any case, I am more interested in real-life use :)
Empirically, yes - I have scanned several ISO100 originals on both
2,700ppi and 4,000 ppi scanners. There is a difference, which is somewhat
analogous to that between fast and fine-grain film but without the grain!
At the same time it's obvious but subtle. The 4000ppi scans show better
tonal smoothness and inner detail, though only look marginally sharper.
Printed on the same Epson 1200, both are perfectly acceptable, especially
in terms of sharpness, but the 4000 scan looks somehow smoother and
clearer, whilst the 2700 appears almost slightly smeared or veiled. But
you'd only really notice this in a side-by-side comparison. After carrying
out this test, I concluded I wouldn't be bothering to rescan all the stuff
I had done at 2700, apart from a few originals which had produced massive
grain aliasing problems. 4000ppi is very much less sensitive to that.
I suspect the Nikon mentioned was having a bad focus day.
Regards
Tony Sleep
- Online portfolio & exhibit; + film scanner
info & comparisons
