Re: Scanning negatives
Re: Scanning negatives
- Subject: Re: Scanning negatives
- From: Michael Schnelle <email@hidden>
- Date: Mon, 05 Mar 2001 12:58:17 +0100
- Organization: Winkler Studios GmbH
Tara Marlowe wrote:
>
Can anyone explain the basic differences between scanning negatives and
>
transparencies. My impression is that is is more difficult to scan negatives
>
but I'm not sure what the problems are or what needs to be done differently.
>
>
Tara Marlowe
>
DIG IT AL, Inc.
>
NYC
>
_________________________________________________________________
Hi Tara !
Scanning negatives ist _very- different to scanning transparencies.
If You calibrate a scanner for trans at first you have to set the white level
in a absolute
transparent part of the film. Then you set the brightest point of your motiv to
R255,G255,B255 ( if it should be absolute white in print ) and set the darkest
point ( deep
black ) to RGB Zero. This gives You a contrast curve you can use with most of
the following scans of correct exposed transparencies, becaus only a correct
exposed and developed trans is a good trans and normally photographers try ;-)
to produce and give away good transparencies.
To scan a neg right you have to make the same procedure in setting white
balance on the mask and setting white and black point whith _every_ single neg.
you will scan.
The first reason is that the color of the orange mask of a negative-film varies
from the type of the film, its speed, the type and condition of the chemical
where it was developed in. The same film developed in a professional lab might
be different to being developed in a big consumers lab or in the minilab right
around the corner.
At next there is the flexibility in epxosuring a modern neg film right. It
doesn4t really matter if You expose a Neg film just one or two stops over or
one stop under. The prints might look the same because the _varying density_ of
over-, under- or right exposed negs can be easily corrected while printing in
the lab. Thats why even professional photographers don4t expose their negs with
the same accuracy like their transparencies.
If You easily try to scan a neg. with the trans-settings and try to correct
color and contrast afterwards in PS our other applications You will see that
e.g. white arreas will be burned out and shadow areas also will be just black
without modulation.
Imagine, a correctly scanned transarencie has a greyscale of 256 steps for each
Color in 8-bit-mode. An inverted negative with the same settings has a much
lower contrast e.g may be starting at R50 up to 150, G30 to 130 and B20 to 120.
From Dmin to Dmax you only have 100 steps in Your origin file. If You correct
the Contrast afterwards in an aplication, you interpolate these physically100
steps up to 256, so 156 greysteps are really missed.
With the white balance at first You set the starting point of the three
contrast curves at the same level. By setting white and blackpoint before
scanning You tell your scanner from which part of its range it has to give You
256 _physically_ steps for each Color.
Thats the reason why it is so important to optimate every transparency,
negative or print allways in the preview before scanning it. The results will
thank You.
There is no common setting but only the right setting for each scan.
Sorry for this container full of words but i hope it will help You a little
bit ;-))
Michael Schnelle
email@hidden