[Alt-photo] Digital negatives help?

johnbrewerphotography at gmail.com johnbrewerphotography at gmail.com
Wed Sep 28 21:07:08 UTC 2016


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
> 
> 
> 
> 
> 
> 
> 
>      
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