HC 110, Sharpness and Developer Exhaust

I read at an alt group where heated discussion made for HC 110 Formula, someone was keeping saying that the sharpness of HC 110 caused by exhausting developer.

Can you spot a light to this ?

Umut

As I understand it, all enhanced sharpness is a by-product of localized developer exhaustion. The developer in a highly exposed area will exhaust faster than the developer in an adjacent weakly exposed area. Because the developer chemicals are in solution, the unexhausted develper in the weakly exposed area will migrate to the strongly exposed area slightly. This increases the edge density of the strongly exposed area and reduces the edge density of the weakly exposed area.

Agitation re-distributed the developer concentration throughout, and thus minimizes the sharpness enhancing.

So, all developers rely on partial exhaustion for sharpness enhancing, when they are used for this effect. It does require that you not agitate too much (stand development being the ultimate in this approach). And developers (such as undiluted D76) won't provide the effect when they are too active to allow exhaustion. This commonly results in uncontrolled highlight density (i.e., burned out highlights).

Charlie

Charlie,

Thank you very much for your excellent answer.

Umut

Local exhaustion can enhance certain adjacency effects ("edge effects") at tonal boundaries. This can increase apparent sharpness. With a general purpose solvent developer such as HC-110 these effects are maximized by diluting the developer and increasing the amount of time between agitation cycles. There is nothing unique about HC-110 when it comes to these effects. You can do this with D76 etc.

Thank you Michael.

Just curious, how are print developers?

Fundamentally print developers are no different than film developers in their mechanisms of action. But with print developers we are concerned much more with tonality, color, and a relatively short developing time than the graininess and sharpness characteristics that often concern us when chosing film developers. The reason is simple - you don't enlarge the print. So the same way we don't worry about sharpness or grain when developing 8x10 film, we don't worry about it when developing printing paper. The adjacency effects referred to in this thread are immaterial unless there is a significant enlargement/magnification factor.

Quote:

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Originally Posted by baachitraka

Just curious, how are print developers?

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I don't think you have enough resolution in the paper to tell a difference. Plus you more 'develop to completion' with short times of usually around maximum 4-5 minutes. For adjacency effects in film developing you usually use very dilute developer, which extends development time, giving the developer more of an opportunity to 'creep' from shadows to highlights in adjacent areas. My print trays are also agitated every 15-20 seconds, probably not enough time for any adjacency effects to actually materialize.

My own experience with using a replenished paper developer, which contains a lot of byproducts from previous printing sessions (restraining action, similar to exhaustion), is that it's merely tonality that changes to slightly softer.

The following site may be useful for general information. http://www.covingtoninnovations.com/hc110

I've been experimenting quite a bit with unorthodox applications of HC-110 including extreme dilution.
Perhaps I came late to the game because I detest the traditional combination of HC-110 and "thick"
Tri-X negs. I realize that some famous work has been done this way, but I just don't like that crisp
salt-and-pepper obvious grit in the skies relative to my own images. With tabular films this doesn't
seem to be such an issue. HC-110 seems to give a straighter line with some films than something
like 76 or any of the old MQ formulas, though not quite as good as TMRS developer. So I suspect
the basic silver particle size to begin with has a lot to do with the mackie line effect and grain
crispness described above, with old-school films behaving a little different than newer very thin
emulsion varieties.