Agitation and highlight density

[Doremus Scudder]

Changing agitation has the same effect as changing development time (or changing developer temperature). In just about everyone's view, it is better to keep temperature and agitation the same/consistent and make the development time the variable.

So, if your highlights are "blown" (I really dislike that term, though!), it means your negatives are overdeveloped. Reduce your development time. And vice-versa.

Exposure is the best control for determining shadow detail. Development doesn't affect them much. So, if shadows you want detail in have none in the negative, you need to expose more (i.e., change your working E.I.). And vice-versa.

Did I just say, "expose for the shadows and develop for the highlights"?

The above, of course, applies to scenes with a "normal" distribution of luminances. If you're exposing for shadows in a dark interior and there are areas of bright sunlit highlights in the image as well, the range of densities in the negative will be much greater than "normal." You deal with these situations by using a lower contrast setting when enlarging (or tweaking contrast in post), developing for less time (see the Zone System), using printing manipulations like dodging and burning, or even using a completely different development strategy, like compensating development. Not every subject fits into the "normal" box. That's why there are contrast options in printing and in post.

FWIW, If you have problems with evenness of development, that's when you need to deal with your agitation method. Personally, I'd be agitating a little more often than every 90 seconds.

Best,

Doremus

[Mark Sawyer]

Changing agitation has the same effect as changing development time (or changing developer temperature).

Not really. We agitate to move new developer in as the old developer exhausts. With stand development (no agitation), the denser areas of the negatives (the highlights) exhaust the developer sooner, which slows development so they aren't "blown out", (sorry). Meanwhile, the less dense areas (the shadows) exhaust the developer much less, so they keep developing for greater shadow detail.

It's not a miracle, but it helps.

[Mark Kononczuk]

Ok,
Thanks.

[Mark Sampson]

Beautiful portrait, Mark.

[neil poulsen]

With too little agitation for HP5 (30 seconds each minute), I had problems with mottled negatives. I increased agitation to 30 seconds at the beginning, and then 10 seconds each minute thereafter. (So, subsequent agitations were at 1:30, 2:30, 3:30, etc.) With this increased agitation, I no longer had mottled negatives.

So, best to first decide on your agitation regime, use it all the time, and then determine development times.

[Doremus Scudder]

Not really. We agitate to move new developer in as the old developer exhausts. With stand development (no agitation), the denser areas of the negatives (the highlights) exhaust the developer sooner, which slows development so they aren't "blown out", (sorry). Meanwhile, the less dense areas (the shadows) exhaust the developer much less, so they keep developing for greater shadow detail.

It's not a miracle, but it helps.

Mark,

You caught me at oversimplification, again

You're describing a special situation; compensating development, which depends on the developer exhausting in the high-density areas, but staying active in the lower density areas thus reducing development in the higher densities. Stand development or reduced agitation development fall into this category (if the reduction in agitation is enough to let the developer exhaust in the highlights). It's a great tool in the toolbox, which I mentioned in my post.

However, when agitation is in the frequency range that prevents the development from being compensating, increasing or decreasing the agitation frequency has a very similar (if not identical) effect to changes in time or temperature, i.e., more or less overall development. However, I don't think it's a good idea to use agitation as a control for adjusting development. I think we all agree that time is the first choice for a variable and that agitation should be done to ensure evenness of development.

If one wants to try a compensating development regime, then, sure, playing around with the agitation frequency is key.

Best,

Doremus

[Mark Kononczuk]

Thanks

[j.e.simmons]

Minor White in The New Zone System Manual from the mid-70s outlines a system of expose for the mid tone, development time for shadows, and agitate for the highlights.

[esearing]

Those of us that chase waterfalls have this issue. I like detailed wet dark rocks but that often pushes white water up to zone 9 or 10 on sunny days when my contrast range is 6-7 stops.
Switching to Pyrocat helped me but also honing on on the right dilution and emphasizing initial agitation near the beginning of the cycle then reducing frequency toward the end was another minor improvement. As others said - it is really about where you place your shadows and highlights during exposure.

Meters and Shutters are the other potential problems you must verify. You may think you are exposing for 1/60th seconds, but in reality you may be exposing for 1/30 and giving even more exposure to the highlights.

Food for though: does the contrast range in your negative have to be the same as your subject contrast - or can you develop a flatter contrast negative and expand it while Printing/Scanning. Alt prints will require higher negative contrast, than a VC Silver paper .