Liam Lawless (lawless@vignette.freeserve.co.uk)
Fri, 12 Mar 1999 00:32:13 +0000
Hi Dave,
I've been getting it in the neck from Sil as well, for using D-512 as the
redeveloper, so sorry for misrepresenting you both. I tried to check your
original message but of course couldn't find it, and making a darker neg and
bleaching back is what I thought you'd said.
The reason I expose my tests as I do is that I rarely bother to plot the
results (couldn't get the "Plotter" software configured for my printer!),
and so I try to be consistent in my testing so that I can make
like-with-like comparisons. I begin by determining the normal exposure as
that which just gives maximum black under the clearest step of the wedge, as
this should give the best shadow separation in a positive containing maximum
black (and hence also in the negative, upon reversal). It is also the
"correct" exposure for a neg that does not need shading. A factor of 3X
was chosen for this series of tests because this again gives fairly good
shadow detail, and is what I would recommend for the majority of original
negs. A higher factor would have been better for highlight separation, but
I wanted to see what happened to the highlights with the techniques I
explored, while keeping the shadows as strong as possible (rather than the
other way around).
As for bleaching back, you'll have to remind me what your idea was as I
still haven't found the message containing it. It'll probably show up in a
week or two, but for the moment it's gone walkabout, as things do in my
machine. But, even doing it wrong, I think the exercise has revealed
something useful: (1) that it don't work well at all, for anyone else who
might think of trying it, and (2) that a superproportional reducer would
probably be better for the purpose than Farmer's. (Last time I read a
textbook, the persulphates were the only superproportiional reducers and I
never had much joy with them - do you know of any others?)
Low contrast first developer and bleaching back - was that your idea? Worth
a try, I suppose (and I will) - I'm sure that reduction could eliminate the
fog, but bleaching back successfully would depend on finding a reducer with
the right characteristics. And personally, I tend not to very good at
things that have to be judged by eye, so, if possible, I'd rather find ways
that involve bleaching/developing/clearing, etc. to completion or for fixed
times.
Sil's developer, as far as I know, was designed for camera films (he
mentions Plus-X, and that it will need tweaking for lith), and as yet I
don't know how it would perform as the first developer for reversal, or
whether it differs significantly from other low-contrast developers. I hope
to get around to all these things eventually, which is why I value
suggestions (and corrections!) from other people. But what I lack in brains
I hope I make up for in enthusiasm and willingness to get my hands wet...
Liam
-----Original Message-----
From: FotoDave@aol.com <FotoDave@aol.com>
To: alt-photo-process-l@sask.usask.ca <alt-photo-process-l@sask.usask.ca>
Date: 11 March 1999 22:07
Subject: Re: Reversal Bleach & Contrast Control
>In a message dated 3/10/99 6:52:24 PM Pacific Standard Time,
>lawless@vignette.freeserve.co.uk writes:
>
>> The test
>> subject was a Stouffer wedge, exposed for 3X the normal time and flashed
6
>> seconds at the same aperture.
>
>Hi Liam,
>
>If you use a step tablet as the test subject, there is really no need to
>specifically find the "normal" exposure than followed by 3x normal time.
You
>could expose it 3x, 5x or any time as long as you get the full scale in.
>Exposure simply shift things up and down. That's why the x axis of a
>characteristic curve of film is labelled *relative* log exposure.
>
>Likewise, when I show my curve with different development, the main thing
is
>to show the complete curve. You will notice that step 1 to 7 in my curves
are
>in the shoulder (flat) region, but it doesn't mean that the film cannot
>separate shadows. It simply means I exposed the film more to get the full
>range. One only needs to find the full curve and then when true negative
with
>image is used, exposure so that it falls within the (separation) range you
>want.
>
>That's why I suggested to Joao the alternate method of determining
exposure.
>
>> Dave's idea a while ago was to make a much darker than usual neg by not
>> overexposing, and take it back to the required density range in a
reducer.
>
>That was not really my suggestion. I would never thought that by exposing
>without the 3x factor but processed the same thing would help anything at
all
>because that simply shift the scale, as described above.
>
>> but I still don't see how it would help
>> highlight separation that was not really there before reducing - this
needs
>> overexposure (the X-factor!) and doesn't happen without it.
>
>Exactly. I didn't think and suggest that it would work. My suggestion was
to
>develop the first stage with a low-contrast developer (for example,
yesterday
>I used LC-1 to develop a negative (well, actually positive), than has 21
steps
>of separation, both measurable and clearly visible). That was what I
>suggested.
>
>But I did mention also that with low-contrast development of the first
stage,
>one would get low Dmax and hence high Dmin after reversal, thus I wasn't
sure
>whether reduction could be used to cut down that much amount of fog.
>
>But that was just my suggestion for anyone who might be interested in it. I
am
>currently using the positive/negative method and am quite happy with it.
>
>> Low-Contrast Developer
>> My tests so far with low-contrast developer have used Sil Horwitz's
D-512
>PP
>> (phenidone-pyro) developer. Dave's LC-1 might have been a more useful
one
>> to start with, but I was attracted by the combination of phenidone and
>pyro.
>
>It depends on whether Sil's formula is low contrast for normal camera
negative
>or specifically formulated to lower the contrast of lith film. If it is for
>normal camera negative, then I am sure it is still to contrasty for lith
film.
>For example, anyone using normal camera film could probably imagine how low
>contrast they will get if they develop their film in D76 1+3 for 5 minutes,
>yet you can see from my curve in PF #2 that D76 1+3 for 3.5 mins is still
>contrasty for APH film! It lowers the Dmax significantly, but it didn't
lower
>the contrast so much that the shoulder region becomes usable region.
>
>I now feel that it is so difficult to describe this kind of things with
words
>when there are charts and graphs in my mind; so I will give up for now. :)
>
>
>Dave S
>
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