Aggie,

The main thing you need to know about the curve of PMK negatives is that it shoulders quite a bit. This can be a very good thing if you are photograhing a scene that has a lot of extended highlight detail because it will extend the range of printable highlights, and a not so good thing in scenes that require a lot of separation in the highlights.

I have a question for Frank regarding the following statement. "Pyro and Catechol affect the shoulder of the slope. The tanning clamps the highlights by not letting fresh developer in after a certain amount of development has taken place."

On what do you base this statement? I have done a lost of testing with both pyrogallol and pyrocatechin developers and it is not my experience that these developers affect the shoulder in any significant way that is different from traditional developers, except for the manner in which the stain color may impact VC papers. For sure PMK shoulders, but in my opinion this shouldering results from developer exhaustion, in the same way that a glycin-based developer like FX-2 shoulders, and not from any inherent tendency of pyrogallol as a reducing agentl to shoulder. The tests I have done with ABC Pyro, Rollo Pyro and Pyrocat-HD, which are much more energetic than PMK, do not show any sign of shouldering in the curves.

Sandy




Metol based developers will cause less curve at the shoulder because they will permit more blocking in the highlights. It can almost seem like the highlights go out of focus due to the blocking."


Pyro and Catechol affect the shoulderof the slope. The tanning clamps the highlights by not letting fresh developer in after a certain amount of development has taken place. Metol based developers will cause less curve at the shoulder because they will permit more blocking in the highlights. It can almost seem like the highlights go out of focus due to the blocking.