Re: Why is paper "contrasty"?

William,

If you go to the Ilford web site, on the B&W products page,
http://www.ilford.com/html/us_english/bw.html
you will find hiding somewhere towards the center of the page an Acrobat
document called "CONTRAST CONTROL" that deals with your question.

Basically, contrast on B&W variable-contrast paper is determined by the
amount of blue that hits the paper. Under the enlarger, low contrast is
achieved by reducing the amount of blue from the enlarger lamp with a
yellow filter.

VC paper is calibrated for tungsten, which is yellow in color, compared
to daylight which is much more blue. So, it's only natural that paper
exposed to "blue" daylight will be more contrasty.

To reduce contrast, use a yellow filter similar to the 00 that you would
use under the enlarger for minimum contrast: it works very well. It
will block some light, compared to not using a filter. But, if you use
Ilford paper, its speed is higher at lower contrast grades than at
higher contrast. As for me, I use ISO 4 when I shoot paper negatives
and it works well for me.

Hope this helps,

Guy

----- Original Message -----
From: "William Erickson" <erickson@hickorytech.net>
To: "ppinhole discussion" <pinhole-discussion@pinhole.com>
Sent: Thursday, July 11, 2002 8:45 PM
Subject: [pinhole-discussion] Why is paper "contrasty"?

> I've thought this through but haven't completely verified it yet, but
I
> wanted to see what others reaction is. B&W paper used as a negative is
said
> to be "contrasty". What does this mean? B&W paper has a sensitivity
range of
> a little more than four stops for any given exposure. Burning and
dodging
> increase tonal range by shortening or lengthening the exposure. If you
meter
> a scene that has an eight stop tonal range and give the average
exposure for
> the scene using a paper negative, you risk having the highlights blown
out
> because they are more than two stops above average, and shadows go
black
> because they are more than two stops below average. If the scene has a
tonal
> range of only four or five stops, your negative won't be contrasty
because
> all the tones lie within the range of the paper. What, then, to do in
> sunshiney scenes, for instance, where the tonal range might be eight
or nine
> stops? If you place the highlight tones of the main object of your
> composition about two stops above average, you will get good tonality
in
> important spots, no blown out highlights, even though you may get lots
of
> black shadows. The implication is, much shorter exposure times (read
higher
> ISO) in bright scenes than in shadowiy scenes (effctively lower ISO),
using
> the same paper. My first tests suggest that a good ISO for Ilford
multigrade
> in bright sunlight might be as high as 15, while 5 works well in
shaded
> scenes. Any comments?
>
>
>
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Received on Fri Jul 12 09:10:16 2002