PMK and paper choice

[philip_sweeney]

Recently in the large format forum a few statements on PMK have been:

Use graded papers for PMK versus variable contrast papers because it

prints the highlights better, etc. (I am paraphrasing). This seems to

contradict what I have read in Hutchings' book. On the other hand

others have responded that they have had good luck using variable

contrast paper.

 

My PMK tests are still preliminary and I have calibrated for use with

variable contrast papers. I only use FP4. I have yet to understand and

realize any of these facts. I have observed an increase in sharpness.

I'd appreciate any response from your experiences.

 

I also just got a 8 x 10 camera and want to do contact prints. On the

subject of highlights: should I consider Bergger 200. Because of the

thick emulsion and a straight shoulder does that mean the highlights

would seperate even more? And how would one expect it to print on

graded versus variable contrast paper.

[dhananjay_n]

I think you are hearing responses from photographers battling two kinds of problems. One set are trying to get good local contrast in the highlights. The other are trying to accomodate long luminance scenes and get good lcoal contrast in the shadows.

 

Pyro based developers have a tanning/hardening and staining effect on the gelatin. This is proportional to silver density and thus the stain is highest in the highlights. With most graded papers that are only blue sensitive, the stain just acts as density (i.e., blocks the light) and that means that the negative is more contrasty than the silver density would indicate. However, VC papers are sensitive to blue and green light, with the ratio between blue and green light being responsible for the contrast - the more the green light, the lower the contrast. The yellow-green stain of a pyro negative will pass some green light. Thus, the stain on a pyro negative acts as a variable contrast mask over the negative (when it is used to print on VC papers). The absence of stain in the shadows means there is a lower proportion of green light in the shadows (greater contrast there) and the greater amount of stain in the highlights means there is a higher proportion of green light in the highlights (lower contrast there). In other words, the shadows will print with far greater local contrast than the highlights. Said differently, the combination of pyro and VC would basically introduce a shoulder on the transfer function.

 

Now, if you have been dealing with the problem of getting good shadow contrast and some detail in the highlights (i.e., if the local contrast in the highlights is not too important) with long luminance ranges, pyro and VC would help. An example of such a scene might be the interior of churches with bright windows. In such a situation, the shoulder would help to extend the density range that could be accomodated by the paper for any grade. Thus, you could print good local contrast in the shadows and the shoudler would keep your highlights (the bright window) from blowing out and being paper base white. However, if you were shooting a scene where local contrast in the highlights were important (e.g., a snow scene), the pyro-VC combination would ensure that while the highlights show some detail, the detail is lifeless because there isn't sufficient local contrast and snap to it (remember, the highlights are being printed predominantly with soft, green light). Therefore, you would resort to harder and harder filtration but that would make getting your shadows correct increasingly difficult. For these folks, the pyro-VC combination would be hell - they would much prefer a graded paper.

 

If you are contact printing, I think the finest paper you could use is Azo. Take a look at the articles on this paper at www.unblinkingeye.com and www.michaelandpaula.com.

 

Cheers, DJ

[david_goldfarb]

...and if you do consider Azo, it does best with a longer scale negative, so you might be better off with ABC pyro than PMK. The grain masking effect of PMK is of no significant advantage for contact printing, and ABC produces less background stain. Read the info in the Azo forum at michaelandpaula.com for more details.