Re: Another scanner related question

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From: Joe (jtait@texas.net)
Date: 11/13/02-08:32:35 PM Z


Guide Dept @ Stouffer Graphics wrote:

>How important is it to have a scanner with a capability to achieve a Dmax of
>4.2 to 4.8 when working with most films that don't even have a Dmax of 3.2?
>Is there a real advantage?
>
>Thanks,
>
>Kevin Morris
>
>
>
>
More dMax is a good thing, and a "0" dmin is just as important. Together
those should indicate the dynamiuc range of the scanner, but there is
much contention on even that point. A "0" dmin is problably impossible,
a 4.8 dmax on a scanner costing less than 10k is probably bogus.
Manufacturer's claims are almost always inflated.

Many, if not most B&W films and their respective densities are within
the range of most "prosumer" and up CCD film scanners. Obvioulsy depends
on exposure, develoment, subject, etc. Slide film is where most people
encounter problems, and even some of the best CCD scanners can have a
lot of trouble in those dense areas. Some scanners/software use
multi-sampling, which basically scans the film with multiple exposures
and averages those areas. This can overcome some of the density
problems, and improve upon some of the "noisy" shadows that a lot of
people complain about. It can significantly add to scan times depending
on how many times a given area is being sampled.

An important point and an often overlooked one is that the effective
density increases with the strong light source that most CCD film
scanners use, as in the callier effect, same as in condenser enlargers.
Even scanners that use diffusers and/or "cold cathode ray" light sources
can quickly be maxed out.

Your best bet is to demo the unit you are considering buying, or get a
gaurentee of return if you're not satisfied, fire that puppy up and scan
the most troublesome shots you have and look at the scan carefully in
PS, etc.

-Joe


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