[alt-photo] Re: Your Approach to Making Negs for Platinum Printing? Ideal Negative Contrast and Dmax?
fdfragomeni at gmail.com
Sun Oct 9 02:23:44 GMT 2011
This has provided me with EXACTLY the information I needed! I am now much
more comfortable with the conceptualization of what I've been approaching
and I'm now confident that I have what I need to approach the empirical side
of this which will be a huge supplement to the visual side of things.
I'd like to ask for one more clarification. The step size on a 21-step
tablet is 1/2 a stop and a 31-step tablet is 1/3 stops. These equate to 1/2
stop equals 0.15 and 1/3 stop equals 0.10, correct?
Thank you all so much. As usual, this group is better then Google!
Seriously, thank you! This is so helpful!
On Sat, Oct 8, 2011 at 6:47 PM, etienne garbaux <photographeur at nerdshack.com
> Don wrote:
> Have you printed a Stouffers step tablet yet with the palladium/platinum
>> mixture you plan to use on the paper you plan to use?
>> Be prepared to exercise some elbow grease testing and then be prepared to
>> ask questions.
> Amen to that!
> Everyone's process is different in alt photo -- your Pt ES will not be the
> same as mine because our solutions are mixed differently (no matter how hard
> we try to match them), you coat differently than I do, at a different
> temperature and relative humidity, your paper is from a different lot (or is
> a different brand), your exposure system is brighter or less bright than
> mine, and they are not spectrally identical, etc., etc., etc. We can tell
> you that you should expect your ES to be around 2.0 to 2.4 for traditional
> Pt once you have the chemistry and exposure working reasonably well, but we
> can't get you closer than that. You will have to do the measurements
> yourself to determine YOUR Pt ES (and it may change as you learn and get the
> chemistry and exposure working better -- it also may change randomly
> according to variables you have not controlled, which can be frustrating).
> As far as process control goes, try to keep track of all variables. Use
> distilled water for ALL solutions. Stick to one lot of one type of paper
> (and be prepared to reinvent the process every time you change paper -- even
> lots of the "same" paper).
> For sanity check purposes, assuming that you are using the traditional Pt
> process with 100% Pt (no Pd):
> Expect a print Dmax in the 1.4 range for starters. As you get the
> chemistry and exposure working better, and try some enhancements, you may be
> able to push this to 1.7. This will give a print DR of Dmax minus paper
> white density in the image area. I use the smoothest, brightest paper I
> can find that is compatible with Pt chemistry, for a paper white density in
> the image area of around 0.06 and a print DR of Dmax minus 0.06. I can
> reliably get a print DR of 1.54 (= 1.6 - 0.06) from traditional Pt.
> Expect a print ES in the neighborhood of 2.1 to 2.4. I have observed them
> as high as 2.95. I cannot recall ever observing an ES lower than 2.0 with
> traditional Pt (no "contrast agent," 100% Pt).
> Frankly, I do NOT recommend printing any image negatives until you have the
> printing process under reasonable control using step wedges. It is too easy
> to be distracted by image details (and often with an image there are no
> areas of stable density large enough to reliably measure). I know it sounds
> geeky and not at all artistic to say you can do all of the
> densitometry/sensitometry with step wedges and then go out, expose one sheet
> of film with a spot meter, process and print the negative, and get a print
> that ranges from the print process's Dmax to Dmin -- but I submit that if
> you learn to do that, you will have a much better understanding of the
> materials and processes you use and a much richer toolbox to serve your
> artistic vision going forward than if you just settle on something that
> seems to work and leave it at that. I commend Francesco for his efforts to
> do so.
> Best regards,
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