cliveh: I think that kintatsu is defining 'consistency' literally.
Consistent agitation is not necessarily going to result in consistent results, as I said, previously. When you agitate every three minutes for the Tri-X/D-23 combination that does not translate into the same results for agitation every three minutes with the Pan F/HC-110 combination. 'Consistenty' there yields wholly inconsistent results. It's a matter of semantics: true consistency would mandate using different (ie, 'inconsistent') agitation methods. - David Lyga
No David, this has nothing to do with it. It is the trade off I don't understand.
Originally Posted by David Lyga
I depend on my routine to help me keep from screwing up, so David's suggestion definitely wouldn't work for me ;).
With a lot of free time and a bunch of extra film and developer, I could see there might be some benefit in designing a customized agitation routine for each different film/developer combination.
[QUOTE=Kevin Kehler;1485613]A film/developer combination which needs 20 minutes of time does not exhaust 1/20 of it's power every minute. Rather than being a linear relationship, I would think it is a sliding scale, where 40% of the development occurs in the first 5 minutes, 20% in the next 5 minutes, etc., etc. /QUOTE]
Just to back this up I was looking at a Kodak instruction book some time ago where there were several pictures of a neg developed from 2 mins to,I think, about 12 mins
I was absolutely astounded at how much the neg had been developed at as little as 2 mins which was only about 17% of the full time.
It certainly made me wonder at how much we need be concerned at mistiming by 30 secs or even 1 minute in a 12 min dev time
First, I didn't mean to imply that there is a trade-off. There are just different ways to skin a cat. My stating that way was a mistake, I should have said something else. Just to clarify my thought pattern in this matter, on this subject we are looking at 1 process, or element, out of several. If 3 identical exposures are made of the same normal scene, the effects of agitation can be easily seen. With your normal agitation the scene appears correct. With a decrease, the contrast is decreased, and the opposite holds true with an increase. When all 3 are printed, the results are visible, and to get the same print from each, printing controls are used. In most cases, we determine our own normals based on our work and vision. Your normal may not for someone like me, without the experience to make it work.
At each step, deviations can be, and are, made to compensate for what we desire in our print. These deviations are based on the scene and our tools, which includes our knowledge. A scene with a longer or shorter scale, one that exceeds our vision, we resort to controls at every stage. Dodging, burning, and grades of printing can be used, expansion and contraction in the negative when developing, and even filters during exposure are tools that deviate from consistent methods.
I was just positing that this is another tool in our box, basing our choice where we are inconsistent, or vary our approach. Based on David's question, I would assume that there are too many factors for a one for all approach, that's just my thought. Of course, it's easier in sheet film when developing only 1 shot, as my values are often outside the ranges for that method.
And, cliveh, your photos are magnificent, so whatever is working for you, don't change!
That pretty much sums it up. I've seen it on my own work. Trying to make every action the same, instead of making the results the same caliber, just got me more confused. I agree with cliveh that consistency in our processes is important, but only in-so-far as it supports our desired results.
Originally Posted by David Lyga
Developers that take longer to develop are less active but do not need less-frequent agitation. Just the opposite in many cases.
Initial agitation is to ensure even absorption of the developer by the negative and to get rid of the initially high amount of by-products. I agitate more at the beginning of development than after the halfway point.
The amount of agitation (if one can even quantify that...) plus the development time = the total amount of development for a given developer. Increasing agitation while leaving time the same is the same as increasing time but not changing the agitation: the overall contrast of the negative is increased. Most of us like to increase time for expansions since it is more controllable and repeatable.
After 50% of the development, most of the shadow areas and mid-tones are developed almost to where they will be at the end of the developing time. It's the highlights and more dense areas that continue to increase in density. The amount of increase with time is proportional to the amount of exposure with more exposure areas developing more than the lower. This means that agitation in the first part of development is what affects the lower-exposure areas more. If one wants evenness in the shadows and lower mid-tones, then a fairly regular agitation early on seems to be logical.
Agitation schemes that use reduced agitation do so for particular reasons. Compared to continuous agitation, reducing agitation to a certain point, say, every 15-30 seconds, has little more effect than extending the development time a bit since the developer is not exhausted in any of the negative areas and the by-product build up is not significant.
Extending the time further (and the exact point this happens is different for different developers, etc.) results in the developer running out of activity in the denser areas of the negative while remaining fully active in the less dense areas (BTW this would happen more quickly in weaker developers, i.e., developers that needed longer developing times...). This results in the compensating effect, which reduces the development of the highlights proportional to density and allows squeezing a bit more information onto the negative. This is the primary reason for most reduced agitation schemes. The more one reduces the frequency of agitation, the more pronounced the compensating effect. The risk is getting uneven development and mottling/streaking.
Another reason for reducing agitation frequency is to get edge effects. On a micro scale, the same mechanism that causes the compensation effect will cause developer in denser areas adjacent to less dense areas to exhaust. However, there is a bit of diffusion of developer across the border between the two areas of differing density. This results in the edge of the dense area being infused with a bit of more active developer, creating a thin line of greater density along its edge. The opposite happens to the edge of the lower-density area, it gets some of the less-active developer which results in a thin line of reduced density along its edge. These lines are adjacent to each other and lend the prints made from these negatives a more contrasty line of definition between areas of different densities creating the illusion of more sharpness or even outlining of forms. These are called Mackie lines and are clearly visible in my grain focuser (I use PMK with a reduced agitation scheme for the last half of developing just to get more of these edge effects. Reducing the agitation in the first half of developing results in uneven development).
So, I would think that an agitation scheme should be chosen on the basis of 1) getting even development, 2) getting the compensating effect one wants (or none at all), and 3) encouraging formation of or preventing edge effects.
If one wants no compensation and no edge effects, then continuous agitation will work just fine, just with a shorter development time than, say, agitation every 30 seconds.
Good thoughts Doremus.
One thought/question though here;
Isn't compensation more about fitting the scene to the paper by encouraging the film curve to shoulder off by discouraging highlight development?
Originally Posted by Doremus Scudder
Seems to me that compensation is actually "designed" to get to more print detail by actually reducing the negative's highlight detail.
Put another way, isn't compensation simply trying to create more of an S-curve than a linear curve?
kintatsu, thank you for the clarification and the compliment.
Originally Posted by kintatsu
No problem. Your work is great stuff, and several of your posts have been quite helpful to me.
Originally Posted by cliveh
Have a great rest of the weekend!