off-topic: scanning

[Paul Schliesser <paulsc@eos.net>]

>PMFJI but you've raised an issue I have been attempting to research without
>much success. Does anyone know if the Minolta Quickscan, or any other 35mm
>film scanner for Mac under $1000 or so, can do this? I mean adjust the
>dynamic range of the scanner to match variations in negative/slide density,
>or scan highlight or shadow only? No one on the scanner list knew, but the
>LUG is much more well attended (an understatement)

Nick,

If you have a very dark or very light film that you are trying to scan, 
you can only adjust within the scanner's dynamic range, which in most 
cases is much smaller than the film's dynamic range.

It's kind of like trying to take a light meter reading outside of your 
meter's EV range. It won't help to set the ASA higher or lower, if it is 
simply too dark or too bright for the meter to read. Any adjustments you 
make while scanning can only "choke" down the scanner's dynamic range; 
nothing can make it go ouside that range.

The under-$1000 scanners all have dynamic ranges well-under 3.0; a 
contrasty film (especially a slide), which can be 4.0, will be impossible 
to capture, no matter what you do, if the scanner only is capable of 2.5. 
Color neg films will be somewhat easier to deal with, with a range close 
to about 3.0.

Very few manufacturers say much about their scanner's dynamic ranges, 
because so few of them are very good. I'm currently using the Polaroid 
SprintScan 35 Plus, which is one of the more expensive desktop models, 
but which has a 3.3 dynamic range. The discontinued Leaf 35 had a dynamic 
range of about 3.7 (!) but took about 20 minutes to do a scan.

High-end drum scanners have ranges as much as 4.0 or higher, but 
generally use photomultiplier tubes (PMTs); consumer-type scanners use 
much less-expensive charge-coupled devices (CCDs) instead.

- - Paul