[Alt-photo] suggestions about cyanotype curve

Alberto Novo alt.list at albertonovo.it
Wed May 24 07:43:45 UTC 2017


>From the picture that you have posted on FB, I measured both an overexposure and a too high density of the negative. Something went wrong from the first step (the determination of the standard printing time), and I would suggest to check this again. With a wrong spt you obtain a wrong color for UV blocking.

Alberto

> Keith (and Don)
> 
> I have not printed an analog step wedge yet, but will add that to my list
> of things to do. I have the stouffer 31 step wedge recommended for use with
> PDN. So perhaps I am overexposing as you suggest.
> 
> Mrhar's method uses the Epson driver, it appears similar in concept to PDN,
> though less complex/sophisticated, though Peter and Mark Nelson may
> disagree with my assessment! The basic steps are:
> 
> - determine dmax/exposure using strip of blank film (pictorico)
> - determine optimal color for uv blocking
> - print step wedge using both of these parameters, with no curve
> - scan and "normalize" target by setting darkest step to black and lightest
> to white
> - within that range find where 10, 20, 30, 40, etc actually are and map the
> curve points (linearization) to create the custom adjustment curve
> - open image to print (real or step wedge), add resulting curve, flip,
> invert, colorize print, etc.
> 
> I'm using Adobe RGB and 2.2 gamma for consistency.
> 
> Mrhar does recommend a method of using a gradient map rather than a curve
> as a somewhat better solution. And he has a 256 step target as well for
> further refinement. Not sure either of those would help me with this but
> might attempt that as well.
> 
> I've posted the original post and the attachments on the FB group since no
> one can see them here.
> 
> Bob
> 
> On Tue, May 23, 2017 at 12:17 PM, Keith Schreiber via
> Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org>
> wrote:
> 
> > Hi Bob,
> >
> > Your attachments are not coming through. Can you give us links to
> > somewhere else to view them?
> >
> > I am only vaguely familiar with Peter Mhrar's method. I know it uses the
> > Epson driver so my suggestions are based on the options available there.
> > Maybe if he is in this group he will chime in with some suggestions. I know
> > he is a member of some of the FB alt-process groups.
> >
> > I've been using PiezoDN for about a year now, but I'm also familiar with
> > and have used other methods including Burkholder, PDN, and other
> > colorization methods (including my own a long time ago), and several
> > variants that use QTR. Some of the principles are the same and can be
> > translated from one method to another.
> >
> > I believe that changing ink density has a proportionally larger effect on
> > the high densities, and that changing exposure has a similar effect on the
> > low densities. Just to be clear, when I say high densities I mean on the
> > negative which is to say highlights on the print, and low densities refers
> > to shadows on the print. I think of it like zone system exposure and
> > development where changing exposure has a stronger effect on low densities
> > (shadows), while changing ink density is analogous to changing development
> > time and has a stronger effect on the high densities.
> >
> > If you are getting full Dmax black all the way down at 70% I think that is
> > telling you that you may actually be over-exposing. You really need to be
> > sure you are using the minimum time to reach maximum black (or blue in this
> > case!) The best way to do this is with an analog 21- or 31-step tablet. If
> > you are trying to do it by comparing clear film edge to uncovered Dmax it
> > is a pretty good bet that it's wrong.
> >
> > It is probably possible to fix your highlight issue with a Ps curve, but
> > it will require a very abrupt and steep transition between steps 1 and 2
> > followed by a flattening out between steps 2 and 3.
> >
> > Man, I wish this list allowed attachments! It's much easier to show this
> > than to describe it.
> >
> > Keith Schreiber
> > jkschreiber.com
> >
> > PS - Don just posted again while I was writing this, and again I agree
> > with him 100%.
> >
> >
> > > On May 23, 2017, at 9:30 AM, Bob Cornelis via Alt-photo-process-list <
> > alt-photo-process-list at lists.altphotolist.org> wrote:
> > >
> > > Thank you Alberto, Keith and Dan for the responses! I see a consensus
> > here. I have a couple of questions to further my conceptual understanding
> > of why you’re making this suggestion, which I will definitely test out -
> > forgive me if these are beginner questions, this is the first time I’m
> > wrestling with some of these parameters. I’m also attaching my screenshots
> > again because at least one person has said they were missing from my last
> > email.
> > >
> > > It might help to note that these are printed with a colorized neg -
> > using the testing suggested in Mrhar’s book, I determine that a particular
> > shade of orange gave the best UV blocking. Dmax was determined using a
> > standard test of different exposure times to determine at what point the
> > dmax under the Pictorico Ultra film matched that of the uncovered,
> > sensitize paper.
> > >
> > > The file PreCurve shows a 100 step wedge printed with those parameters
> > and no adjustment curve. Basically the range of tones is limited to about
> > patch 70 on the dark end and 11 on the light end. Everything higher than 70
> > is the same max black and everything under 11 is pure white. Patches 11-70
> > contain all the distinct values of the compressed tonal range of the Ware
> > cyanotype on this paper. The PostCurve file shows the same chart after
> > adding my adjust curve create from PreCurve. You can see that steps 0-5 are
> > white and then there is a big jump at step 6 and after that, the tonal
> > range isn’t bad the rest of the way.
> > >
> > > Your suggestion is to lower ink density in the neg, which would lead to
> > a darker print with the same exposure time. I can do this in the color
> > density slider in the epson driver or I could use a longer exposure time,
> > if I’m not mistaken. Are these equivalent, except for the fact that the
> > former would result in using a slight amount less ink and be a faster
> > exposure?
> > >
> > > I think what the result of doing this would be that the range of
> > distinct tonal values in the Precurve target which are currently 11-70
> > would shift downward though still consist of the same number of patches.
> > For example, instead of 11-70, the range might be 5-64. There will be more
> > pure black patches and fewer pure white patches. I think that this would
> > lead to more “work” being needed in the last 10% of the curve representing
> > the darkest values and less work being needed in the (currently
> > problematic) last 10% of the highlight part of the curve. Currently this is
> > the case and the PostCurve I end up with does much better with the darker
> > values, so maybe a further shift in this direction is a good thing. Is that
> > the goal? Why would the PS curve handle adjusting a wider range of pure
> > black values to their proper tones rather than the tones in the top
> > highlight range? Maybe it’s easier to lighten tones that are already there
> > than to introduce tones into pure white?
> > >
> > > Is my characterization of what would happen to my PreCurve correct? Why
> > would this help the end result? Certainly I will test this and find out
> > what happens and if it helps, but I’m interested in why this would be the
> > case or if I’ve got it wrong to begin with.
> > >
> > > This conversation is extremely helpful to me on both a practical and
> > conceptual level, so thank you again for chiming in!
> > >
> > > Regards
> > > Bob
> > >
> > >
> > >
> > >
> > > --------------------------------------
> > > www.bobcornelis.com
> > >
> > >
> > >
> > >
> > >
> > > On May 22, 2017, at 11:37 PM, Alberto Novo via Alt-photo-process-list <
> > alt-photo-process-list at lists.altphotolist.org> wrote:
> > >
> > >> I agree with Keith who is agreeing with Don.
> > >> You could print a few test prints with -5%, -10% and -15% ink and find
> > which is the best. If you are used with maths, you could also plot the
> > density values to find the right amount of ink.
> > >>
> > >> Alberto
> > >>
> > >>> I agree with Don. You need to dial down the Dmax on your neg a bit.
> > I'm not sure how to do that with the method you are using to make them. If
> > it uses the Epson driver, maybe you can go into Advanced Media Control and
> > change the Color Density setting to -10% and see if that is enough. Of
> > course, you will have to make a new correction curve afterwards since it
> > will decrease density throughout the scale.
> > >>>
> > >>> Cheers,
> > >>> Keith
> > >>>
> > >>> Keith Schreiber
> > >>> jkschreiber.com
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>> On May 22, 2017, at 12:49 PM, Don via Alt-photo-process-list <
> > alt-photo-process-list at lists.altphotolist.org> wrote:
> > >>>>
> > >>>> 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
> > >>>>>> _______________________________________________
> > >>>>>> Alt-photo-process-list | altphotolist.org
> > >>>>> _______________________________________________
> > >>>>> Alt-photo-process-list | altphotolist.org
> > >>>>>
> > >>>>
> > >>>>
> > >>>>
> > >>>> --
> > >>>>
> > >>>> Color Folio
> > >>>> www.colorfolio.com
> > >>>>
> > >>>> 2550 Lewis Dr.
> > >>>> Sebastopol, CA 95472
> > >>>> 707.824.8910
> > >>>> 888.212.7060 toll free
> > >>>> _______________________________________________
> > >>>> Alt-photo-process-list | altphotolist.org
> > >>>>
> > >>>> _______________________________________________
> > >>>> Alt-photo-process-list | altphotolist.org
> > >>>
> > >>> _______________________________________________
> > >>> Alt-photo-process-list | altphotolist.org
> > >>>
> > >> _______________________________________________
> > >> Alt-photo-process-list | altphotolist.org
> > >
> > > _______________________________________________
> > > Alt-photo-process-list | altphotolist.org
> >
> > _______________________________________________
> > Alt-photo-process-list | altphotolist.org
> >
> 
> 
> 
> -- 
> 
> Color Folio
> www.colorfolio.com
> 
> 2550 Lewis Dr.
> Sebastopol, CA 95472
> 707.824.8910
> 888.212.7060 toll free
> _______________________________________________
> Alt-photo-process-list | altphotolist.org
> 


More information about the Alt-photo-process-list mailing list