Pt/Pd parameter questions on reading Arentz

[smieglitz]

So I've decided Dick Arentz' book Platinum & Palladium Printing seems pretty thorough and is probably a good manual for learning about process calibration and other topics which may be transferable to other alternative processes. I am wondering if his definitions of certain parameters are taken as fairly universal, i.e., are most platinum printers speaking his language? I ask because of the wide variation in Density Ranges and Exposure Scales I see listed in other alternative process books for various processes.

So, I want to make sure I understand what he's saying and if it agrees with your practice.

First, he cites a DR of 1.4 as ideal for Pt and 1.65 for Pd and defines the DR of negatives as the density difference between zones VIII and III. His negative density values appear to be uncorrected for FBF where he refers to 0.30 as the "useful shadow density" (pg. 19) or ~ 0.20 above FBF, i.e., a net density of ~ 0.10. On the previous page, he states the "threshold for shadow density" is usually 0.15 to 0.25 as a result of base & fog & lens flare. So I'm thinking he is talking uncorrected gross density values (and his graphs seem to support that interpretation).

Second, he measures the exposure scale of the paper/emulsion combo based on a "90% black" value and a "discernible white" step value. It appears 90% black is two steps lighter than maximum or "Total Black" as he calls it. " Discernible White" appears to be the threshold light gray just slightly darker than paper or maximum white. Is that correct?

He also states that in order to find 90% black you need at least two shadow steps that have merged. But, once the ES is determined wouldn't you adjust the exposure so that max density was produced at step 1 in the minimum time?

And finally, the ES of the paper/emulsion will be the number of inclusive steps from 90% black to discernible white multiplied by 0.15. Is this how most Pt/Pd printers measure the ES?

Joe

 

[bill schwab]

Joe,

Finally reading it, eh? I remember you saying that you had it, but hadn't gotten into it. I've always thought of it as a great book and as far as I know, his practice as described is pretty widely accepted. I may be wrong, but it has been a big help to me.

So I'm thinking he is talking uncorrected gross density values (and his graphs seem to support that interpretation).

The sensitometry is where a lot get hung. Isn't there something about B+F and flare are not enough to factor into the print? Or is it just flare? Time to dig up the book again.

It appears 90% black is two steps lighter than maximum or "Total Black" as he calls it.

This is the way I have always understood it. -The white being the first step with some tonality.

I found that I can get too obsessed with the sensitometry aspect of it all. But then, I still have trouble creating a perfect palladium neg where I don't need a drop of Na2 to juice it a little. Not much, but I hope it helps some.

 

[Alan9940]

Hello Joe,

Dick's book on Pt/Pd printing is, I believe in most circles, considered the "bible" of this type of alternate process. Please keep in mind, though, that the information in this book is primarily directed to the production of in-camera negs for Pt/Pd printing and all the attendent information that goes along with this. Dick has been working quite closely with Mark Nelson producing digital negs for Pt/Pd printing. A couple of years ago I took a workshop with Mark and Dick and can assure you that some of the techniques Dick uses today are different than those presented in his classic book. Not sure how you're proceeding for Pt/Pd printing, but just something to keep in mind.

Hope this helps.

 

[Don12x20]

Arentz Book Questions

First, he cites a DR of 1.4 as ideal for Pt and 1.65 for Pd and defines the DR of negatives as the density difference between zones VIII and III. His negative density values appear to be uncorrected for FBF where he refers to 0.30 as the "useful shadow density" (pg. 19) or ~ 0.20 above FBF, i.e., a net density of ~ 0.10. On the previous page, he states the "threshold for shadow density" is usually 0.15 to 0.25 as a result of base & fog & lens flare. So I'm thinking he is talking uncorrected gross density values (and his graphs seem to support that interpretation).

>> Arentz is a extremely disciplined user of the densitometer (testeing, testing, testing..) but when printing he doesn't care what B+F is...the only thing important to Dick is that he is 0.3 above B+F. He just doesn't measure B+F on the negatives, just III and VIII. His methodology includes an aid (not in the book) to tell you exactly what the exposure is (Nuarc units or time) based upon your measured DR plus what the mixture you are using (NA2, although it shoudl also work for A+B+C). Take one of his courses to get this nifty tool....its a clear slider overlaid on a nomagraph. It works very well for all normally developed negatives but pyro negatives give different results because neither a blue-channel nor UV-specific densitometers give correct readings, as found out by those of us that brought Pyrocat HD negatives to his Masters Workshop. Dick is currently figuring out whether he wants to write a fourth edition...the tool would be in that book.


"Second, he measures the exposure scale of the paper/emulsion combo based on a "90% black" value and a "discernible white" step value. It appears 90% black is two steps lighter than maximum or "Total Black" as he calls it. " Discernible White" appears to be the threshold light gray just slightly darker than paper or maximum white. Is that correct?"

>> Yes this is correct. Dick's stated method is that he uses black up to only 90% black with in-camera negatives. However he uses the full tonal range with the digital negative methods he has been using (only!) within the last 2-3 years. Independent tests at the recent (Aug 2007) Photographer's Formulary Dick Arentz Masters Workshop showed an astute observer could tell, by looking at the blacks, whether a fine platinum print was created using in-camera or digital negative. This worked on Dick's prints as well as several workshop participants prints.

"He also states that in order to find 90% black you need at least two shadow steps that have merged. But, once the ES is determined wouldn't you adjust the exposure so that max density was produced at step 1 in the minimum time?"

>> Yes, that's in the book.

"And finally, the ES of the paper/emulsion will be the number of inclusive steps from 90% black to discernible white multiplied by 0.15. Is this how most Pt/Pd printers measure the ES?"

>> Works for most of us. Depends upon whether you have a 21 step or 31 step tablet (0.15 or 0.1 per step). YMMV

"Joe

"

>> Regards, Don Nelson

 

[smieglitz]

Thanks for the replies. They have cleared up a lot for me.

I'm actually interested in his terminology and method for several processes including Pt/Pd, Salted Paper, Albumen, VDB, and Cyanotype. Though I may do a few inkjet negatives to show students the method, my personal primary interest is in-camera or duplicate negatives from interpositives.

Joe

 

[smieglitz]

Another question popped into my head. If he defines the DR of negatives as the density difference between zones VIII and III, is he talking about a camera exposure Zone VIII, or is he calling his "discernible white" print value Zone VIII and looking at that density on the negative. Ditto on the other end. Is his Zone III also his "useful shadow density" of 0.30 above FBF?