[Alt-photo] suggestions about cyanotype curve

francis schanberger frangst at gmail.com
Fri May 26 18:58:48 UTC 2017


How can I put this delicately?

If this works with the digital negative work flow you are using, make sure
that you flatten your image with the curve prior to inverting the image to
a negative. It may not be the cause of your tonal range grief but I have
made this mistake, students have done it and I have even seen a colleague
at my school get stumped by the inverted curve error.

-francis



On Thu, May 25, 2017 at 1:13 PM, Christian Nze via Alt-photo-process-list <
alt-photo-process-list at lists.altphotolist.org> wrote:

> Less ink
>
> Le 22 mai 2017 20:50, "Don via Alt-photo-process-list" <
> alt-photo-process-list at lists.altphotolist.org> a écrit :
> >
> > Sounds like you have too much UV blocking with your digital negative.
> >
> > Have you printed a regular analog step tablet to determine the contrast
> > range of your process?
> >
> > Just a thought.
> >
> > Don Bryant
> >
> > -----Original Message-----
> > From: Alt-photo-process-list
> > [mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf
> Of
> > Bob Cornelis via Alt-photo-process-list
> > Sent: Monday, May 22, 2017 1:25 PM
> > To: alt-photo-process-list at lists.altphotolist.org
> > Cc: Bob Cornelis
> > Subject: Re: [Alt-photo] suggestions about cyanotype curve
> >
> > Hi Peter
> >
> > Thanks for the suggestion. I think, however, that my problem is not lack
> of
> > contrast but, rather, too much contrast, at least in the highlights. The
> > rest of the tonal range, all the way down to the shadows are behaving
> > properly.
> >
> > Regards
> > Bob
> >
> >
> > On Mon, May 22, 2017 at 10:10 AM, Peter Friedrichsen via
> > Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org>
> > wrote:
> >
> > > Bob,
> > > Without seeing your samples, I can suggest one possibility; a thick
> > > coating of the sensitizer. I have found that contrast increases, the
> more
> > > one applies to the paper. It may be due to the uv blocking effect such
> > that
> > > the sensitizer that is bound to the paper never gets a chance of
> exposure
> > > in the shadow areas due to the filtering effect of the sensitizer
> sitting
> > > overtop. Whatever the reason, that is my observation. I know others
> will
> > >  suggest other possible causes.
> > >
> > > Peter Friedrichsen
> > >
> > > > On May 22, 2017, at 11:04 AM, Bob Cornelis via Alt-photo-process-list
> <
> > > alt-photo-process-list at lists.altphotolist.org> wrote:
> > > >
> > > > Hi All
> > > >
> > > > I'm looking for a little help finishing a custom curve I've made for
> > Ware
> > > > cyanotype printing using Peter Mrhar's method from Easy Digital
> > > Negatives.
> > > >
> > > > I'm having problems getting a smooth gradient from steps 0-10. Pure
> > white
> > > > is step 0, pure black step 100. My tones from steps 10-100 are pretty
> > > > linear, but within the highlights I've got about half the steps pure
> > > white
> > > > and then there is a steep jump to a value of close to 10. I'd like to
> > > find
> > > > a way to get a smooth gradient in this part of the tonal range.
> > > >
> > > > Without a curve, all steps from 0-14 are pure white so the curve has
> to
> > > do
> > > > a lot of work to introduce a gradient in a relatively small portion
> of
> > > the
> > > > curve range. I've tried tweaking with the curve in that range by hand
> > but
> > > > without success.
> > > >
> > > > I was wondering if there are other tricks people know of to handle
> this
> > > > type of situation, either chemically, through exposure, development,
> > etc.
> > > >
> > > > My first wash is in 3% citric acid for a couple of minutes, 20 sec in
> > > > peroxide solution, then about 25 min in water.
> > > >
> > > > I've attached 3 screenshots for anyone interested showing my
> pre-curve
> > > and
> > > > post-curve step wedges (100 steps), and the curve itself (note it is
> a
> > > > pre-inversion curve).
> > > >
> > > > Thanks!
> > > > Bob
> > > >
> > > >
> > > > --
> > > >
> > > > http://www.bobcornelis.com
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> > > > Alt-photo-process-list | altphotolist.org
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> > >
> >
> >
> >
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> >
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-- 
francis schanberger

www.francisschanberger.com


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