Pyrocat HD question

**John Brady** · 12-Sep-2006, 07:16

I have been using t-max rs for many years and I am not happy with it.

I am interested in trying Pyrocat-HD to develop t-max 100 4x5.

Do you still benefit from a staining developer If you scan and print digitaly? Everything I have been reading refers to enlarging to silver vc paper.

I am in search of richer tones in my landscape photography.

Also I live in South Florida where the water is very warm in the summer months. Will this developer work well at 75f?

Thanks in advance.

**Ron Marshall** · 12-Sep-2006, 09:20

I have not tried Pyrocat-HD yet (I will be running tests soon), but many of the posts I have read on this site mention that the stain masks grain and therefore is beneficial for negatives intended for scanning.

Search for posts by Sandy King or Pyrocat-hd and scanning. There has been loads of discussion on this site on this subject in the past year.

**Bruce Watson** · 12-Sep-2006, 09:42

One theory is that the difficulty in scanning metalic silver images is due at least in part to Callier Effect. If, for a given density, you take away some of the silver and replace that density with stain, it stands to reason that you'd deminish Callier Effect. The question is, is it enough to matter?

I don't have an answer to that yet. I've been looking around, but not finding any comprehensive answer on the 'net or in the forums. So I'm resigned to doing the testing myself.

I'm interested in Pyrocat-HD primarily because it creates a stain that is more neutral. I'm thinking it might scan more easily. I'm also interested because many people swear by it, particularly for rotary processing which I will be doing.

I'm going to compare Pyrocat-HD to XTOL 1:3 for my tests. It'll be interesting to see how the negatives, and then the scans, compare. The thing I'm looking for, like you, is better tonality in my scans. Sadly, it's probably going to be several months before I get a chance to do the work. Sigh...

**Ron Marshall** · 12-Sep-2006, 09:47

Originally Posted by Bruce Watson

I'm going to compare Pyrocat-HD to XTOL 1:3 for my tests. It'll be interesting to see how the negatives, and then the scans, compare. The thing I'm looking for, like you, is better tonality in my scans. Sadly, it's probably going to be several months before I get a chance to do the work. Sigh...

Bruce, I intend to do the same tests as you, with TMY (hopefully sooner than four months). What film(s) do you plan to run the tests with?

**Ken Lee** · 12-Sep-2006, 10:02

The Callier effect is seen to the degree that light rays reach the film in parallel. In darkroom imaging, "Cold" light heads have been used (instead of Condenser heads) to deliver light through a highly diffused white filter, and tests have shown that such images resemble contact prints - in as much as the Callier effect is mitigated by a non-parallel light source.

My Microtek 2500f scanner uses a diffused light source, and so do the Epsons, as far as I can tell. I have scanned lots of TMY developed in PyroCat HD, and have never seen anything attributable to the Caller effect.

Perhaps dedicated film scanners and high-end analog scanners use point-source lighting. If that's the case, stained would probably fare better than non-stained negatives, but only an apples-to-apples test would prove it definitively.

**Bruce Watson** · 12-Sep-2006, 11:30

Originally Posted by Ken Lee

The Callier effect is seen to the degree that light rays reach the film in parallel. In darkroom imaging, "Cold" light heads have been used (instead of Condenser heads) to deliver light through a highly diffused white filter, and tests have shown that such images resemble contact prints - in as much as the Callier effect is mitigated by a non-parallel light source.

I suspect that the Callier Effect with a diffuse light source isn't zero. I think this because of the idea of conservation of energy. If light hits a surface that it can't penetrate, and that doesn't absorb it, it has to reflect off that surface. So I'm thinking that even with a diffuse light source, one still gets some amount of Callier Effect.

I think (and it will take the research of better people than me to prove or disprove this idea) that this is one of the factors why some people ooh and ahh over contact prints. They show the least amount of Callier Effect. The light still scatters, but it can't travel very far when it does since the negative and the paper are held in tight contact. As a result, you get a bit (nearly negligible, but not quite) better sharpness, and a bit better local contrast - better tonality if you will.

That said, diffuse lighting does show less Callier Effect than does collimated light. In that it's the metallic silver that is scattering the light, and one can replace some of the density of the metallic silver with stain, one should see some reduction of Callier Effect in a stained negative. This should be true with enlargers or scanners. The effectiveness of a stain in scanning should, as you point out, be less with a diffuse light source and more with a collimated light source.

The reason I'm going to do some testing on my own is to find out if I can see it in my prints. Because I suspect that all this theoretical argument may have little practical importance, and the only way to find out if it matters to me, is for me to run the tests.

**sanking** · 12-Sep-2006, 13:26

Originally Posted by Bruce Watson

I
The reason I'm going to do some testing on my own is to find out if I can see it in my prints. Because I suspect that all this theoretical argument may have little practical importance, and the only way to find out if it matters to me, is for me to run the tests.

That is often the case, but it is interesting to discover the truth on one’s own.

As I mentioned earlier, I have done no specific testing as of yet. When I began scanning large format negatives I was so excited with the ability to apply tonal corrections and clean them up in Photoshop, and so pleased with the outcome in printing from digital negatives, it never crossed my mind to interrupt the fun to actually test what was happening.

However, I have speculated on three areas of image quality that I consider germane to what further testing may reveal. Those areas are grain, apparent sharpness, and resolution.

Grain – If one develops their negatives exclusively for scanning it makes sense to develop them to a relatively low CI. This minimizes grain and also maximizes resolution. In this circumstance, I personally do not believe that staining developers will offer any advantage over a good non-staining formula such as Xtol. However, if negatives are developed to relatively high CI for printing on AZO or alternative processes there may well be and advantage to the staining developers. How much advantage will depend on format and amount of magnification?

Apparent sharpness – Apparent sharpness depends on both resolution and edge effects, but primarily the later. Most of the popular Pyro staining formulas are high acutance developers because they enhance edge or adjacency effects. Scanning can not capture this effect of the film because the edge effect lines, some as small as 1 micron in width, are simply too narrow to be captured by most scanners, even high quality drum scanners. To do so I calculate that one would need a scanner with resolution of about 10,000 spi with yield of at least 80%. I don’t have that kind of scanner.

Resolution – Most of the scientific literature on developing indicates that resolution is a quality of films and is not much affected by developer, and Dr. Richard Henry reached the same conclusion after extensive testing of his own. But, it turns out that staining developers were not used, at least they were not in Dr. Henry’s testing or in any of the literature I have reviewed. So, I recently tested this myself, using a USAF chrome on glass resolution target with maximum resolution of 225 lppm. I tested two staining developers and two non-staining developers. Guess what. It turns out that the staining developers gave slightly better resolution with every film and in every single test. The difference was not great, say for a given film like Delta 100 we get about 90-100 lppm with the staining developers, and 75-85 with the non-staining developer. Is this difference significant? Well, potentially it could be, depending on the capability of your scanner and the amount of magnification of the final print. Obviously, the weakest link in any imaging system determines final image quality, so if your scanner has a maximum potential of 50 lppm, which is in fact very, very good, there is no way to take advantage of 100 lppm on the film. So let us say, on this point it depends, but regardless, I definitely found some advantage in the staining developers for resolution. BTW, the developers tested were PMK and Pyrocat-HD, which gave about equal resolution in every test, and D76 1:1 and Xtol 1:2, which also tested about the same.

Sandy King

**Ron Marshall** · 12-Sep-2006, 14:20

Originally Posted by sanking

However, I have speculated on three areas of image quality that I consider germane to what further testing may reveal. Those areas are grain, apparent sharpness, and resolution.

I will compare Pyrocat-HD and XTOL for two different uses: as a general developer for negatives to be scanned; as a compensating developer.

The main aspect of image quality I will consider is tonal gradation.

**Pronier Jean Claude** · 29-Sep-2006, 07:49

Hi, I just received Camera view magazin and read an article about staining developers, subtitled - a conversation with some expert- .
I find the article not deep enough about fundamental aspects of such developers. I'm not a specialist technically involved in densito measures. I have a densito but for B&W only (a Leiland) so unable to work acurately with stained negatives. I use from months the Sandy formula Pyrocat developer with TRIX and Bergger pf and be very satisfied with it. I get negatives suited for contact printing on AZO and Centennial too.
Anyway I would ask about something which is pointed as specific character by users of staining developers and commented as dubious by others. I mean the staining PROPORTIONAL to silver density on the negative.
Does it exist acurate work about that linearity silver/staining, in order to confirm that property?