RE: [APML] Newbie Scanning Stuff

["Eric Barber" <ppsupport@cox.net>]

Jerry,

Thanks very much for this. I was able to make progress, although some
fiddling is still required. The problem I'm having, and attempting to
resolve is acheiving a nice dark background, without the green, brown
mottled appearance, while still pulling out the foreground detail. I have a
gut feeling that a dark scan will give me the background I want, and that
there must be some way, via masks or something, to pull the foreground out.

Thanks again,

Eric Barber

-----Original Message-----
From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org]On
Behalf Of Jerry Lodriguss
Sent: Wednesday, May 15, 2002 4:29 PM
To: astro-photo@seds.org
Subject: Re: [APML] Newbie Scanning Stuff



>  The
>slides look great through the slide viewer, but I'm having trouble getting
a
>decent scan. Can anyone suggest some starting point settings / methods /
>tips?
>
>The film was Fuji Provia 400f, I'm using VueScan, and a Minolta Dimage Scan
>Dual II.


Hi Eric,

First thing you should know is that scanners have the most trouble with the
maximum optical density that slides are capable of.  So generally you want
to expose your slides so that the sky background has some transparency,
that is, so they are not totally black.  Sometimes push processing helps
with this too. Fuji 400 pushes very well.  If you expose long enough you
might start to pick up some sky glow if you are shooting anywhere near
light pollution, but you can get rid of that after the scan in Photoshop.

Assuming your slide does not have a sky background that is completely
black, in VueScan go to the Color tab and change the Color Balance setting
from White Balacne to AUTO LEVELS. Then change the % for the black point
and white point to ZERO for both. This will probably solve the excessive
contrast problem from the autoexposure in the prescan.

If the preview of the slide is then too dark, you can increase the
brightness with the Brightness control in the Color Tab.

You can also tweak the color balance a bit with the Red, Green an Blue
Brightness controls, but these only offer global corrections.

Unfortunately there is no pixel value readout in Vuescan, and no way to set
the black and white points with curves, and no curves or levels.

If the sky background in your slide is completely black, your scanner may
just not be able to handle this maximum optical density.  Some scanners
will let you increase the exposure for the CCD.

It's also a good idea, especially for slides, to multi-sample and export
the file at a high bit depth if the scanner will let you.  Since VueScan
offers such limited controls in the prescan, the high bit depth will really
help when you make adjustments in Photoshop.

Jerry


Astrophoto Web Site: http://www.astropix.com

Photoshop for Astrophotographers Book:
http://www.astropix.com/APBOOK/0_PROMO/PROMO.HTM

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