[pure-silver] Re: New color head "discoveries"
- From: "Rob Champagne" <app@xxxxxxxxxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 13 Jan 2005 17:56:23 +0000
big snip
> The filters of a color head will not give you the full
>range of contrast available from VC paper with the use of
>dedicated filters. They should give you a couple contrast
>grades on either side of "normal" but filters should be used
>to obtain the maximum and minimum contrast values.
big snip
>---
>Richard Knoppow
I wonder whether my observation is true for other dichroic filter head
enlargers.
The Ilford Y+M figures for grade 2 on my Durst CLS501 head enlarger give approx
an ISO grade 1 result on paper.
It occurs to me that because dichroic filtration does not seem to give as much
contrast as filter sets, and because most new enlargers have dichroic heads,
that Ilford, and maybe other manufacturers, use this to its advantage in terms
of film speed.
To get a true ISO grade 2 using ilfords G2 Y+M figures for my enlarger I have
to give the negative more development which in turn gives allows a faster film
speed.
So what I'm speculating here is that modern film speeds may be tailored by the
manufacturers to suit printing on dichroic heads with Y+M filtration.
It should be noted that by using increased development of the negative the
overall contrast obtainable from a dichroic is not far short of a true G5 and
if you take neg development far enough then a true G5 is obtainable from a
dichroic head.
It all depends on what you are tailoring your development to. Do it to 0
filtration and your negs will be too soft for G5 on dichroic settings. Do it
to G2 Y+M settings of your dichroic head and you will get faster film speed and
availability of higher contrast in your print.
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