Pyro question?

[stradibarrius]

I have never used Pyro. I use either HC110 or Rodinal. I have been very happy with my results. What advantages does pyro have over these two developers? Are there certain situations that call for pyro?

[mikebarger]

For me I like skies and clouds better with 510 Pyro than HC110. However, if HC110 was all I had I'd still be happy. I shoot HP5 in LF and Tri-X 400 in 120mm.

[Andrew O'Neill]

Using a pyro developer enables me to print the negative on gelatin silver papers or alternative processes, such as carbon transfer printing. HP5 negatives print beautifully on gelatin silver papers but I have never been able to get the same negative to print well in carbon. Extended development only drives up the b+f, increasing the alt process exposure time resulting in ugly, veiled shadows. I have no problems with FP4 and TMY-2.
Anyways, you will notice much smoother tonal transitions especially in the highlights, less grain. The negatives will look slightly thinner than conventionally developed negatives (you should back off on development due to the stain density) and scan beautifully.
Another thing about pyro (I use pyrocat-hd) is the ability to do stand or semi-stand development for enhanced edge effects.

andrew

[Gem Singer]

Gordon Hutchings contended that it's impossible to blow out the highlights when using a Pyro developer.

My technique is to rate the film at box speed, spot meter, and place the shadow areas, where I want some detail, in Zone III. Then, develop normally.

The highlights were very difficult to print when I used a robust developer like HC-110, or DD-X.

No more blown out highlights now that I have switched to Pyrocat-HD.

[bob carnie]

I would say that he was almost right, I have seen a few impossible neg's to print using Pyro developer but not many.

Gordon Hutchings contended that it's impossible to blow out the highlights when using a Pyro developer.

My former technique was to rate the film at box speed, spot meter, and place the shadow areas, where I wanted some detail, in Zone III. Then, develop normally.

The highlights were very difficult to print, especially I used a robust developer like HC-110, or DD-X.

No problem now that I have switched to Pyrocat-HD.

[Andrew O'Neill]

That's a good point, Gem. So very true.

[Jay DeFehr]

Barry,

this a "can-O-worms" kind of question, but my opinion is that a developer should be judged by its total IQ pkg, and not for any single characteristic, unless of course you have something very specific in mind. I also think choice of developer for LF is a special case with different requirements from small formats that are enlarged many times the size of the negative, and just about any developer will produce acceptable results for most users, under most circumstances.

Long scale UV printing processes favor pyro (staining/tanning) developers, because of the increase in contrast provided by the image stain, but the staining developer shouldn't produce excessive general stain, which would defeat the advantage.

Situations in which highlight compression is an advantage also favor a staining developer, provided the neg is to be printed on VC paper. Stained negs will always print on VC paper with a split-grade effect -- more contrast in the low values than in the high values.

Some users claim scanning favors staining developers, but I can't say that's true or false, and defer to those with more scanning expertise, which is just about everyone. In my limited scanning experience with low end consumer scanners, I don't see much difference, but that's hardly surprising.

My all-time, all-purpose favorite developer is 510-Pyro, because it does everything so well, and so dependably, BUT for maximum overall IQ, nothing I've ever used beats Halcyon, a non-staining ultrafine-grain developer, used in a replenished system.

[Jay DeFehr]

There were a few posts while I was (slowly) writing mine. To Hutchings' assertion that it's impossible to blow out highlights using a staining developer, I say, nonsense. When printing on graded papers, the stain increases contrast geometrically, and it's very easy to blow highlights with an energetic staining developer like ABC Pyro, or 510-Pyro. I've regularly developed films in pyro developers to densities above log 3.0. Not all pyro developers are compensating developers.

[cdholden]

Jay,
Can you elaborate on geometric increase of contrast? Is that like a linear/proportional comparison?
Without having any tools to measure or calculate density, I only have my own negatives and a naked eye for comparison in the trial and error game. Having some numbers or relationship may help, but I just try to get a successful print one negative at a time. I've found (after your suggestion) that graded papers do help with consistency in the final result.

[Jay DeFehr]

Hi CD,

By geometric I mean that the increase in stain density is not linear relative to the silver density, but proportional to it. If we plot two curves -- one for silver density, and one for silver + stain density -- the two will diverge at some point, near the toe (for most developers). The gap between the two curves will increase with increased density, at a geometric rate. This is a little confusing because contrast always increases at a geometric rate, which is just what a characteristic curve represents, but the deviation from the silver-only curve is also geometric.

So, it's not only possible to blow highlights, but an inevitability given excessive development, which is a bit circular, since excessive development is defined by blown highlights.

Like so many other pyro myths, there is a grain of truth in this one. To the extent that a pyro developer is a compensating one, there is a tendency for it to protect against runaway highlight density. This protection is not conferred by the stain (except when printing on VC papers), but in spite of it, by the tanning action of the developer. Tanning developers harden the emulsion in proportion to exposure just as staining developers stain in proportion to exposure. As the emulsion hardens, access to it by fresh developer is restricted, creating a braking effect in the highlights, or compensation. Proportional stain, as described above, works in direct opposition to the compensating effect of tanning.

For example, Obsidian Aqua is a compensating/ tanning/ staining developer. The braking effect on highlight density by tanning is enhanced because it is a single agent developer that does not regenerate in solution, and because it's used in a very dilute solution, with intermittent agitation. By adjusting the ratios of the 3 ingredients in OA, one could make a highly compensating, and non-staining developer. An increase in the metabisulfite (which creates sulfite in combination with the carbonate) eliminates the stain, and the increased highlight density along with it, but retains the tanning responsible for the compensating effect. There will also be an increase in the appearance of grain because the grain-free stain portion of the image density is replaced by silver density.

You might also be able to infer from the above how image stain decreases film speed. A fascinating and complex subject, as always!