[Alt-photo] Digital negatives help?

John Brewer johnbrewerphotography at gmail.com
Wed Sep 28 22:08:13 UTC 2016


Totally agree Don. Stouffers are invaluable particularly for monitoring the total scale of a process process. Test strips only get a dmax nothing more. 

Sent from my iPad

> On 28 Sep 2016, at 22:16, Don Bryant via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote:
> 
> Absoulutely. I mainly use the Stoufers to monitor the process. Digital step
> tablets aren't consistent, the Stouffers is.
> 
> On Sep 28, 2016 5:07 PM, "johnbrewerphotography--- via
> Alt-photo-process-list" <alt-photo-process-list at lists.altphotolist.org>
> wrote:
> 
>> While I do use a Stouffer can't you just do a test strip with neg
>> substrate overlapping a sensitised area on paper looking for where the two
>> areas are the same dmax Don? Or am I missing something?
>> 
>> Sent from my iPhone
>> 
>>>> On 28 Sep 2016, at 10:01 pm, Don via Alt-photo-process-list <
>>> alt-photo-process-list at lists.altphotolist.org> wrote:
>>> 
>>> How did you establish your Standard Printing Time?
>>> 
>>> -----Original Message-----
>>> From: Alt-photo-process-list
>>> [mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On
>> Behalf Of
>>> Niranjan Patel via Alt-photo-process-list
>>> Sent: Wednesday, September 28, 2016 3:48 PM
>>> To: alt-photo-process-list at lists.altphotolist.org
>>> Cc: Niranjan Patel
>>> Subject: Re: [Alt-photo] Digital negatives help?
>>> 
>>> Don:
>>> 
>>> OK, let me show the method behind my madness.
>>> 
>>> Please click the link and use altalt as a password to get in the page
>> where
>>> I have added two jpegs illustrating my procedure.
>>> 
>>> http://niranjanpatel.zenfolio.com/p596379492#h1ede1c3b
>>> 
>>> 
>>> After developing my initial process based on the composite black on
>> B9180, I
>>> set out to do the colorizing negative in search of higher UV opacity
>> needed
>>> to bump up the white point of the prints.  For that I eliminated the
>> Blue as
>>> a variable which is probably a safe choice, so I don't have to work in
>> the
>>> 3D.  Then I varied R and G from 0% to 100% with step size of 10% (that
>>> translates to 25-26 in RGB points) to come up an 11x11 matrix that is
>> shown
>>> on Figure 1.  The grid lines were made with pure black (0/0/0) so the
>>> comparison of under-performance and over-performance can be visibly made.
>>> The square on the top right corner is also 0/0/0.
>>> 
>>> Figure 2 is the resulting scan of the print.  It can be immediately seen
>>> where the best cluster of squares is.  I picked the square, marked by a
>>> circle, corresponding to the 51/128/0 in the negative as the best
>> candidate
>>> based on both the numbers as well as the fact that as one moved away from
>>> it, the squares became significantly noisier, even when the readings were
>>> comparable.  (I have noticed that the print from a colorized negative has
>>> more noise than from a straight one, particularly in the mid to darker
>> tones
>>> for which I am working on a solution to - a subject for discussion at
>>> perhaps an another time.)
>>> 
>>> Next I took 51/128/0 as my center and created another checker board,
>> varying
>>> R and G in smaller steps of 2% (equivalent to 5 in RGB points.)  Figure
>> 3 is
>>> the result of that.  After printing and scanning, as seen on Figure 4,
>> the
>>> results point to a new center of gravity for opacity which is at
>> 61/118/0,
>>> albeit the improvement is modest - from 223 of 51/128/0 (marked by a
>> circle)
>>> to 227 of 61/118/0 (marked by a square.)  We are really splitting hairs
>>> here, but the difference is real.  It was encouraging that although I did
>>> both of these a a few days apart, the results were consistent.
>>> 
>>> Now about the additional black layer as per your suggestion:
>>> 
>>> You can easily test this quickly by producing a
>>> series of digital step tablets with progressive opacities (of the black
>>> layer) printing them all on a single sheet of OHP
>>> <<<<
>>> 
>>> You really don't have to do the step wedge, only a block of 0/0/0 (before
>>> colorizing) in order to simplify the process.  So if I take that 0/0/0
>> block
>>> and colorize with my old green shade of 51/128/0 and put the Black layer
>> on
>>> Multiply and vary the opacity.  "Blending if" options at this point do
>> not
>>> matter.  Here is what happens to the final values:
>>> 
>>> Black Layer Opacity -  Final R/G/B values
>>> 
>>> 0% - 51/128/01% - 51/127/03% - 50/125/05% - 49/124/0 7% - 49/122/010% -
>>> 47/119/0
>>> 
>>> All of these values are in the matrix of Figure 3, within 2 or 3
>> points.  I
>>> have marked the 5% point as A and 10% point as B to illustrate.
>>> 
>>> 
>>> So are you going to start printing salt after you run out of POP?
>>> 
>>> <<<<
>>> 
>>> I have a lb of Silver Nitrate sitting in my fridge for about the same
>> time
>>> as the POPs (hopefully it is still good) that says I ought to.  Also have
>>> some Pt/Pd chemistry that I may want to do some printing with.  May be
>>> before salt.
>>> 
>>> :Niranjan.
>>> 
>>> http://niranjanpatel.zenfolio.com/
>>> 
>>> 
>>> 
>>> 
>>> From: Don via Alt-photo-process-list
>>> <alt-photo-process-list at lists.altphotolist.org>
>>> To: alt-photo-process-list at lists.altphotolist.org
>>> Cc: Don <donsbryant at gmail.com>
>>> Sent: Tuesday, September 27, 2016 5:12 PM
>>> Subject: Re: [Alt-photo] Digital negatives help?
>>> 
>>> Niranjan,
>>> 4.  I use AdobeRGB 16-bit color space in Photoshop as well as in the
>>> scanner.  Printing is done at HP's "Maximum DPI" from 1200 dpi files.
>>> My question was buried at the end of my long-winded backgrounder in
>>> yesterday's post.  In any case, I think I have the answer to that one
>> now.
>>> 
>>> I grok a lot of what you are describing, but I question your
>> methodology. If
>>> your blocking color is R=51, G = 128 then I would think you still have
>> head
>>> room to extend the UV density of your digital negative using that
>> greenish
>>> color path. However if you wish to use a black ink layer to target the
>> steps
>>> or part of the adjustment curve it should be very simple to do with the
>>> Blend If method I listed for Henry.
>>> 
>>> IME, doing that makes the negative get very dense quickly. At the time I
>> was
>>> testing this method, I was producing VDB and kalitype negatives and found
>>> that the opacity of the black only layer needed to be set to a very low
>>> amount - like about 5%. You can easily test this quickly by producing a
>>> series of digital step tablets with progressive opacities (of the black
>>> layer) printing them all on a single sheet of OHP. I flatten all of the
>>> layers before printing and use the Text tool to label each giving me a
>>> record to keep in my testing files. That way you can hone the required
>> value
>>> with one or two sheets of paper. For those two processes a black ink
>> really
>>> isn't needed when printing with Epson OEM pigmented inks.
>>> 
>>> So are you going to start printing salt after you run out of POP?
>>> 
>>> Don Bryant
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> Alt-photo-process-list | altphotolist.org
>>> 
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>> _______________________________________________
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