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
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