PMK VS Pyrocat-HD Stuff

[sanking]

Originally Posted by jdef

Donald,
Sandy's curves don't show the differences in midtones that you describe between PMK and Pcat, and suggest PMK might offer better highlight separation, depending on the subject.
Jay

PMK negatives show a lot of highlight compression from shouldering, the longer the time of development the more compression. Compression and separation are antagonistic concepts, i.e. if you have a lot of compression there will be less "separation" between tonal values. The "separation" in the highlights will always be better with Pyrocat than with PMK because the latter shoulders more.

What I said was that there may be some scenes with very high highlight values that will print better with PMK than with Pyrocat-HD (or with a traditional developer that does not shoulder). This should be very clear from the comparison curves I provided for PMK and Pyrocat-HD.

Sandy

[Donald Miller]

Originally Posted by jdef

Thank you, Sandy. That's how I understood your post as well. Donald claims that staining developers give better midtone separation than non-staining developers, and that Pcat gives better midtone separation than PMK, neither of which I understood from your data, or my own experience.

Jay

Jay, Let me begin by saying that I don't consider a zone III density as belonging in the midtone classification. I would identify midtone densities as those that would reside in the Zone IV to Zone VI densities. If you will take the time to examine the curves that Sandy, DJ and others have posted on Apug, Unblinkingeye and other sites then you will clearly see that the effects of proportional stain begins to become noticeable in the densities that I have mentioned. In order for this effect to be measured with some degree of accuracy one would need to measure the density with the blue channel of a color densitometer or a UV channel on a densitometer (if so equipped). This does have a measureable effect on enlarging papers since the sensitometric sensitivity of the representative materials by Kodak, Forte, and Ilford clearly indicate that the materials are most sensitized by light in the "blue" spectrum. This becomes ever more noticeable when we depart from VC materials and move to graded materials. Beyond that, if you will consider for moment, the higher density and density ranges that we utilize in materials such as Azo then the effects of proportional staining become more pronounced. I realize that you are very enthused by the developer that you seem to be working with. I have not had the opportunity to try it. I probably would not entertain trying it myself since I am quite happy with what I am using. However, please understand, I do not have an agenda here and for that reason I find no benefit in debating this issue with you. This would be interesting if you had sensitometric data based on hard densitometric analysis. However I have not seen any instance where you have approached this from that orientation. I hope that this explains my position to your understanding.

[lee]

Originally Posted by jdef

Donald,

If you don't consider zones 4,5,and 6 to be midtones, in a scale that covers 9 meaningful zones, then I suppose that's your prerogative, but these are important midtones to me. Jay

Jay,
I don't pretend to speak for Donald as he can do that very well for himself. But, the above quote is not what Donald said. This is his quote that I have pasted here:

"Let me begin by saying that I don't consider a zone III density as belonging in the midtone classification."

Misquoting anyone is not advancing the argument here.

lee\c

[sanking]

Originally Posted by jdef

Donald,

I do have an agenda; to understand how these staining developers differ from one another, and how they collectively differ from non-staining developers, when used with either VC papers, or graded papers. Sandy has adressed that very question, excepting the comparison of staining, and non-staining developers, right here in this thread, with the "sensitometric data based on hard densitometric analysis" that you require. of your own.

Jay

At some point when I make it back home I will include a curve made with a print from a PC-TEA negative along with the curves made with the PMK and Pyrocat-HD negatives. This will allow anyone to compare the curves and draw their own conclusions as to which is in theory better, or perhaps better stated, which would be serve our needs in a given situation.

It is important to remember that any suggestion that a certain developer is superior to another only makes sense within a very tight framework in which we specify the film being used, the lighting conditions, the strength of the working solution and the intended printing medium. Even if we were to limit the use to VC papers there are still a wide number of possibilities that might tend to favor a particulr type of developer, of which the three broad categories are, 1) extreme shouldering-compensating developer such as PMK, 2) moderate shouldering developers such as Pyrocat-HD, and 3) traditional non-shouldering developer such as D76, Xtol or PC-TEA.

For example, with Tri-X 320 and subjects with a lot of extreme highlights and tonalities from Zone I to IX (or X if possible) PMK would definitley be my choice. For subjects of less extreme highlights, but with a full range of tonalities from Zone I to Zone IX I would prefer Pyrocat-HD over both PMK or a non-compensating developer, but for subjects withi reduced tonal range, say Zone II to VIII, my clear preference would be a traditional developer non-compensating type of develper.

However, we need to bear in mind that the differences are very small between developers so the best one, in my opinion, is the one we understand best.

Sandy

[Thomas Bertilsson]

Sandy,

I have read many of your posts, both at the MichaelandPaula forum and here, and every time you enlighten me.

"However, we need to bear in mind that the differnces are very small between developers so the best one, in my opinion, is the one we understand best."

Amen to that!

Thanks for your expertise and your willingness to share with the photo community. I, and I'm sure many others, appreciate your efforts!

- Thomas Bertilsson
Saint Paul, MN

[sanking]

Originally Posted by jdef

Hi Sandy,

I
When you developed your negs to a CI of .7 to match the .52 negative printed on graded paper, did you measure the contrast of the .7 neg with the V filter of your densitometer? If so, do you remember what it was?

For that reason, I would not consider a staining developer a good, general purpose developer, for printing on VC papers. I know from experience that general purpose, non-staining developers like D-76, Rodinal, Xtol, and PC-TEA can handle very high contrast scenes with proper dilution, but it will be interesting to see your curves and compare them to Pat's. Maybe Pat will post his as well.

Jay

I measured both set of negative in Blue channel mode. A Visual reading would have no doubt provided a more accurate indicaton of the actual effective printing density of the negatives on VC papers, but the primary purpose of the tests I did was to evaluate the difference between graded papers and VC papers using a common reading.

To repeat what I stated earlier, if one wants to compare the characteristics of a staining developer with those of one that is non-staining, it is essential to be specific as to lighting conditions, film, and dilution of the developer. I just really don't believe that either or us has done enough comparison work to state with any degree of authority that traditional developers are better than staining developers as general purpose developers for printing on VC papers, or vice-versa, though I can theorize that one or the other might have an advantage in specific lighting situation with a given film.

Sandy

[AlanC]

Sandy,
You say that for subjects of reduced tonal range your clear preference would be for a traditional non compensating developer.
It would be interesting if you would care to name which one.

Alan Clark

[sanking]

Originally Posted by AlanC

Sandy,
You say that for subjects of reduced tonal range your clear preference would be for a traditional non compensating developer.
It would be interesting if you would care to name which one.

Alan Clark

If I did not qualify the previous statement let me do so now. It was only meant to apply to subjects of reduce tonal range using films that have a fairly straight line curve, and when printing on VC papers. By a traditional developer I would mean something like D76 1:1 or Xtol, though PC-TEA would do just as well but with slightly bigger grain.

Sandy

[sanking]

Originally Posted by jdef

Hi Sandy.



I didn't mean to seem authoritative, I simply stated a hypothesis. Isn't that how we refine our testing? I'll restate my hypothesis more clearly:

If a stained negative must be developed to a higher VCI than a non-stained negative to achieve a given print contrast on VC paper, then a staining developer would not be as effective as a non-staining developer, as a general purpose developer for printing on VC paper.


Jay

I don't follow the logic of your conclusion. Why would a staining developer be "less effective" than a non-staining one in the situation you describe above? It appears to me that in order to make this statement you must first define what you mean by the use of the term "effective", which may not mean the same thing to all persons in all situations. From my perspective, the most relevant issue is, "can we can adjust dilution, time and tempeature with the developer to create the contrast we need for printing on VC paper with the kind of tonal range we desire"? And the answer to that question is definitely yes in my experience, though you must do the work and calibrate the developer to your film and process. Of course, if you plot curves the sensitometry is a bit more complicated, but to be fair most people don't do that anyway.

And there are other issues as well. The impact of the stain on the printing characteristics of the media is only one of the relevant considerations involved in comparing staining-tanning type developers with traditional non-staining ones. Sharpness, ability to hold detail in extreme back-lighted situations, and grain-masking, are other things that come into play that must also be considered.

Sandy

[Kirk Keyes]

"If a stained negative must be developed to a higher VCI than a non-stained negative to achieve a given print contrast on VC paper, then a staining developer would not be as effective as a non-staining developer, as a general purpose developer for printing on VC paper."

And what is your definition of "less effective"? If you are trying to compress highlight values, then a yellow-stainging developer like PMK would be more effective.

Kirk - www.keyesphoto.com