Comments from previous article system:
By Tom Hoskinson - 03:22 PM, 02-14-2006 Edit Rating: None
Jeff Pyrocat-HD will meet (and/or exceed) all your goals. Plus, it has the additional advantage of long stock solution shelf life and there is a enormous amount of data on its performance with many different films. This data includes the performance of Pyrocat-HD with tabular grain films (Pyrocat-HD works very well with them)
By Tom Hoskinson - 04:07 PM, 02-14-2006 Edit Rating: None
Jeff, you state "6.The filmholder with films can be put in the alkaline developing bath back for 2'30? after the fixing process. This will enhance the stain. After this, the film has to be rinsed."
If you do this, the overall stain will increase, but the image forming stain will not. Gordon Hutchings is no longer recommending this practice for PMK development.
By Jed Freudenthal - 08:00 AM, 02-15-2006 Edit Rating: None
I published a combo of two HD developers, each with their own specifications and with their own image quality. The specifications complement each other. One can never put contradictory specifications in one formula, whatever the formula. Therefore, one cannot compare one developer with a combo of two. The difference of the two HD developers is obvious in the final print. However, I plan to determine the MTF behaviour of the two developers with different films. I developed this combo because I was unable to catch the great wealth of light circumstances in Europe. I tested the combo where the great painters of light went to. First of all, the Netherlands with the Dutch light; then France the land of van Gogh and Cezanne, Italy at Sorento and Cornwall in England. In these areas, I think, one should test a high definition developer.
It is right that the overall stain will increase too when the film holder is put in the alkaline afterbath back. But this is one of the parameters one can vary in the modified ABC formula. It will influence the tonal separation in the shadows.
Jed
By Jed Freudenthal - 08:36 AM, 02-15-2006 Edit Rating: None
I focussed on QA aspects, rather than shelf life. The shelf life of solution B of the ABC formula is an example of problems. The PMK is better, the older it is; it is just like fine chesse or wine. Some people mix their developer with old developer. And so on. I could have put the pyrocatechein in solution, but study the chemistry of pyrocatechein, I thought I better add it just before development. In other words: shelf life is a vague concept. But again: MTF tests will be used to determine real stability.
Jed
By Tom Hoskinson - 01:15 PM, 02-15-2006 Edit Rating: None
Jeff, please publish sensitometry and densitometry data for these developers so that we can compare it with the other published film/developer data. I'd like to see your data for Kodak TMAX 400, Efke 100, Ilford FP4 Plus and Fuji Acros.
By titrisol - 02:04 PM, 02-15-2006 Edit Rating: None
This is funny, I just read an article about the Pyro developers in one of the old PhotoVision Magazines.
By Jed Freudenthal - 08:53 AM, 02-16-2006 Edit Rating: None
Tom, as I said, I will make densitometric (Modulation Transfer Function) measurements in the future. I hope soon. In the past, I had a microdensitometer in my lab; unfortunately that is not the case anymore. However, when we had an APUG 'pub'meeting of the Dutch group one week ago, I discovered that one of our professional members has the instruments in his lab, to provide the photographic industry with data. He told me, I could use his instruments. So, you can see, we not only drink beer in our pubs!
To speak with the people in the 'Kodak research labs': The image quality of the final print will be determined by the MTF's of the different parts in the chain. This applies in particular in high definition imaging. PMK, and likewise pyrocat HD, are developers with two developing agents. As you can expect from these developers, they have adjacency (Eberhard) effects. I expect an discontinuity in the high spatial frequency range in the MTF. It is a matter of taste, but many people experience this as unpleasant in the final image quality. This is, why the sharpening up in computer image manipulation is hardly used today. And that is the reason that I have focussed on developers with one developing agent. It is not without reason that the staining ABC formula is such a beautiful developer. And notice that my pyrocatechine formula is a non-staining formula.
Anyway, I have to make a research program in the near future. You asked me to include the T max 400. Do you mean the present (last year) version? I usually work with FP4+, HP5+, Fortepan 200, 400, Tri-X, 320 and 400. Then adding PMK and pyrocat HD would be nice too ( I have them in my lab). But, .... I still need some time to do the real work: photography.
Jed
By sanking - 04:26 PM, 02-16-2006 Edit Rating: None
Jed,
You suggest that developers like PMK and Pyrocat-HD that have two reducing elements are more likely to produce adjacency effects than a single reducer developer like ABC. What is the basis for this observation? I have not seen this stated before and don't understand the theory of why it would be so. If you could cite a source for this I would be most appreciative.
Sandy
By Tom Hoskinson - 06:30 PM, 02-16-2006 Edit Rating: None
Jed, You state:“4.The developer (referring to your Catechol Developer Recipe) is non-staining.”This is difficult for me to understand given the small amount of Sodium Sulfite your Catechol Developer recipe contains (i.e, 1 ml of Solution B).Catechol/Pyrocatechol together with low sulfite, produces image stain that can be difficult to see by visual examination of the negative but which produces a significant increase (increase proportional to the amount of exposure) in the UV density of the silver image.Have you confirmed with transmission densitometry that this developer does not stain the silver image?
By jdef - 04:22 AM, 02-17-2006 Edit Rating: None
Jed,
you might have a look at my developer formulae here:
http://www.digitaltruth.com/techdat...stainingdev.php
it seems we had similar goals in mind, but very different approaches to the problems involved. Thanks for posting your formulae.
Jay
