Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Lawrence Smith 
<lsmith@l...> wrote:
>How much better is the 2450 with
> respect the sharpness, noise, shadow detail than the 1640?  I don't 
want to
> drum scan these until we're making prints.  Anyone have real 
experience with
> both scanners?


I don't have experience with either scanner, but I recently purchased 
a 1660 photo scanner (i.e. with built-in transparency adaptor) so I 
can offer some general comments...

The 1660 is spec'd at the same, 1600x3200 resolution as the 1640, but 
with higher bit-depth (48 vs 42). I consider 1600dpi to be the 'true' 
optical [/hw] resolution of this scanner as scans @ 3200 are 
noticeably softer (interpolated).

This is probably adequate for scanning many photos for web pages. 
However I have found that while it is quite good at digging up shadow 
detail, it exhibits severely blown highlights, and furthermore on 
dark images (or that have dark areas), there is a noticeable 
uneveness of illumination from the scan, with a bright strip (from 
the poorly-diffused bulb) down the middle. There may be (I hope)
workarounds that ameliorate these defects.

There also seems to be a focus problem with some slides in thick 
mounts, that can be eliminated by taping the unmounted slide to a 
piece of glass then placing it so the emulsion side is in contact 
with the platen (which also gives you access to the full frame).

Compared with my experience with an old SprintScan 35 dedicated slide 
scanner, that does not have nearly the dynamic range of the 1660, but 
does offer 2000 dpi optical resolution, and relatively good 
interpolation to 2700 dpi, I do get markedly better results from the 
higher resolution. You see film grain on a 400-speed 35mm film 
(unlike the 1660 @ 1600 dpi).

So I would say the higher resolution and increased bit-depth of the 
2450 will probably yield a higher percentage of good/usable scans.