PMK VS Pyrocat-HD Stuff

[Tom Stanworth]

I hate to butt in and make a stupid remark, but I think it is simple.

Compare and contrast. If you like it, it is good. If you prefer it (regardless of why) it is better. As Sandy points out, one cannot seperate out the variables as they are inter-related. Along with that stain comes highlight compensation, greater acutance for given grain size etc. I have said on a number of occassions that I am not going to use pyrocat at all costs (ie if I cannot get the look I want out of low contrast scenes) but interject because this seems to have decended into "if a cat had wings would it be better at flying than a dog with flippers would be at swimming?". Regardless of what VCI a neg is dev'd to, if, for example, it has finer grain than the conventional neg, greater sharpness and better (subjective) tonality and seperation, it is better in those areas. However, it may be worse. One cannot say 'all things being equal', because they are not. It is like saying if "If Fp4 plus had the grain of Tmax 100, but was still a conventional film of ISO 125.......would it be better than Tmax?" It cant be! I'm sure you know what I am trying to say!

I'll go for what I like and it may or may not be pyrocat for evreything, I'm undecided, but it will certainly be pyrocat when I want those things we attribute to it, control of highlights, ultra sharpness.
Tom

[gainer]

Jay, I hate to tell you this, but the stain image does add contrast, even on VC paper. Just not as much as it does on graded paper or other printing material. Furthermore, it makes possible a greater change of contrast on VC paper by use of blue or magenta filtering than with non-staining developers. Consider the following experimnt: develop a negative in, say, PMK and bleach out the silver part of the image with Farmer's or color blix. There will be a stain image remaining. In order for that image to reduce contrast, it would have to be a positive image. Even though it will appear quite weak, it is still a negative from which one can get a print on a high contrast graded paper or on VC paper. You could try this experiment. I have.

[aldevo]

So if the image stain does add appreciable density for VC printing - what role does the color of the stain play?

For example, is it true that a brown-staining developer (e.g. DiXactol or Pyrocat-HD) would add more printing contrast to a VC paper than a green-staining developer, such as PMK?

At first guess I would think so since the greenish stain might allow more greenish light to strike the green-sensitive, lower-contrast emulsion of the paper than a brownish stain.

[sanking]

Pat,

if what you say is true, how do we account for Sandy's example of a negative with a VCI of .6+ printing on G2 VC paper, when a non-stained negative with a CI of .52 would print on the same grade?

Jay

Perhaps it may be explained by the fact that the reading that indicated a CI of .6 + was made in blue channel mode, which as you know is an arbritrary color to use for the measurment since the effective printing density of a VC paper is not the same as the CI suggested by a densitometer reading made in blue.

What we need to find, it seems to me, is a color filter that could be used to more closely approximate the actual printing density of a stained negative on VC papers. I gather that such a filter would pass a high percentage of Visual light in the Green but also a fair amount of Blue, perhaps weighted about 60%-80% toward the Green. This would not solve the sensitometry issue 100% for VC papers but I think it might be useful for most normal lighting situations.

Sandy

[sanking]

So if the image stain does add appreciable density for VC printing - what role does the color of the stain play?

For example, is it true that a brown-staining developer (e.g. DiXactol or Pyrocat-HD) would add more printing contrast to a VC paper than a green-staining developer, such as PMK?

At first guess I would think so since the greenish stain might allow more greenish light to strike the green-sensitive, lower-contrast emulsion of the paper than a brownish stain.

The major complication is that VC papers are sensitive to light in both the blue end of the spectrum (which is the higher contrast) and green (lower contrast). There is no question but that the greenish-yellow stain of PMK (and other pyrogallol developers that I have tested) allows more of the green light to strike the lower contrast green sensitive part of the paper emulsion. his is the primary reason why prints made on VC papers with PMK negative shoulder more than do prints made with Pyrocat-HD negatives. There is also no question but that the brown stain of Pyrocat-HD (and other pyrocatechin based developers that I have used) adds more printing contrast to processes that are primarily sensitive to blue or UV light (but not green) than does the green stain of pyrogallol based developers.

What has not been very fully explored is the exact role played by VC filters in the way they interact with the stain. Lots of room for experimentation in this area in my opinion.

Sandy

[Jon Shiu]

re: filters and pyro
I have a neg that printed with most contrast with a #3.5 ilford filter. 4, 4.5, 5 were all less contrasty (or close to same) prints! HP5+ in WD2D+, condenser light, Ilford MGIV paper.

Jon

[Kirk Keyes]

What we need to find, it seems to me, is a color filter that could be used to more closely approximate the actual printing density of a stained negative on VC papers. I gather that such a filter would pass a high percentage of Visual light in the Green but also a fair amount of Blue, perhaps weighted about 60%-80% toward the Green. Sandy

Sandy - I think you may already have the filter you are describing for this. Did you get the "Ortho" filter with your D200-II? This is pretty close to what you described above. A lot of blue with a good amount of green.

Or, perhaps, a Wratten Cyan CC filter. Perhaps a CC50C or even stronger. The Wratten #44A Light Blue-Green (aka Minus-Red, which means cyan) would be a strong version of the CC filter.

A couple more that may be a good match - Wratten #11 or #13 yellow-green filters or the Wratten #38 light blue or #38A Blue with extended green.

And if you really want to be daring, the old Kodak Grade 3 Polycontrast printing filter is close to this requirement.

If you guys don't have one, I suggest getting a copy of the Kodak Filters for Scientific and Technical Uses book. Once you figure out what wavelength you are interested, you just have to flip through the pages and look at the little absorption diagrams. Look for a filter with a center peak in the 480-500 range...Very handy and quick.

Kirk - www.keyesphoto.com

[Kirk Keyes]

Oh, I forgot to mention - none of the filters I suggested above will account for the fact that the ratio of blue and green light in some stained negs is changing with density...

[sanking]

Oh, I forgot to mention - none of the filters I suggested above will account for the fact that the ratio of blue and green light in some stained negs is changing with density...

Kirk,

I only have the Blue, Visual and UV tubes for the Gretag D200-II, not the Ortho. But some of the other filters you suggest may provide a productive path for experimentation.

As you say, no filter will account for the fact that the ratio of sensitivity of blue:green, and the consequent shoudering in the upper middle tones and highlights, changes with density.

Sandy

[sanking]

re: filters and pyro
I have a neg that printed with most contrast with a #3.5 ilford filter. 4, 4.5, 5 were all less contrasty (or close to same) prints! HP5+ in WD2D+, condenser light, Ilford MGIV paper.

Jon

Am I reading this right? Your WD2D+ negative printed with more contrast with a #3.5 VC filter than with a #4, #4.5 and #5? And did you verify the results with a second printing?

Assuming John's experience can be repeated, anyone have an idea why this might happen?


Sandy