[pure-silver] Re: Any advice for purchase of densitometer.
- From: RH Designs <richard@xxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 23 Dec 2004 09:37:26 +0000
JohnStockdale wrote:
>
>So if I know that a densitometer was in fact giving me just silver density,=
>=20
>I would be happy enough. I could then compare the effect on paper of=20
>stained and non-stained negatives of approx equal silver density, and make=
>=20
>up a table of adjustments.
Juergen says "the B&W densitometer measures a large spectrum around the
maximum sensitivity of the human eye (green colour) it will also measure
yellow, green or brown stains. The problem of interpreting the density
values (translsate them into filter setting) is caused by the point, that
if you print the negative on a multigrade paper, you use the Yellow and/or
Magenta filter. In case of a stained negative the resulting filter is
different from the enlarger filter. I.e. both filter values are changed.
Also the stain is more colourful in the highlights (darker parts of the
neg.), compared to the shadows. This fact leads on one side to the
wonderful highlight details, that are one of the main reasons for using
pyro. On the other side it shifts the necessary light and shadow exposure
into two different directions.
In other words: The densitometer reading of pyro negatives is not so useful
as the one on colour neutral negatives."
So IOW the density reading from a pyro negative may not be an accurate
guide to the required contrast filtration if you're using VC paper - which
is fair enough. As the instrument measures a wide colour spectrum it will
presumably read both the silver and stain densities and give you an
effective total.
Regards
Richard
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