Agitation vs. Time

[bruno]

I've tried to search a little bit, but I didn't find anything yet...

the question is the following:

 

I know that increasing development time I increase the film contrast.

More in the highlights than shadows, something in between for midtones.

 

What happens increasing agitation? Does this affect the characteristic

curve exactly as increasing developing time or temperature, or does it

work differently?

 

Basically I'm searching a way to increase a little bit the midtone

contrast, without affecting (too much) highlights.

[mark bridges]

Ansel Adams suggests making hc-110 diluted 1-30 from stock solution.agitation intervals 15 sec. every 3-4 mins. going upwards of 18-20 mins. Your asking for specialized development which should be tested before hand, and using a densitometor. You can seek highly dilute developers and semi-compensating techniques or you might just give Diafine a try.

[neal_wydra1]

Dear Bruno,

 

Be consistent with your agitation technique. It is much easier to carefully modify the time than it is the agitation.

 

Neal Wydra

[bruno]

Unluckily Diafine is almost impossible to find in Germany, tried several places without success. I've seen a shop in France that sells it, but it costs something 5-10 times more than in the US. US online shops won't ship chemicals to Europe.

 

I basically use TriX with XTol or ID-11. I'm quite happy with the results, expecially with XTol. I was just wondering about the difference between increasing agitation vs. increasing times... I've been through Ansel Adams' "The Negative" several times, but I have to say that the difference between increasing agitation and increasing time isn't explained.

 

I'm not asking for something like "do this for 20 sec, then 1 min this and that"... it was more a theoric question in order to do some experiments myself without throwing away rolls.

[neil_grant]

try to optimise your neg contast using dev time and dilution. The more you agitate,

the more you will prevent the build-up of adjacency effects that can enhance

sharpness in you negs.

[chris_waller]

Three things affect development, time temperature and turbulence (i.e. agitation). Increases in any of these will increase the development. More development means more contrast, AOTBE. Changes in the tonality of the neg, by which I mean the mid-tones, is dependent upon the type of film and the type of developer. Some films, e.g. Agfa APX 100 give well modulated mid-tones - it's in the nature of the film. As for developers, I use Rodinal at 1:50, 20 C and agitate by inversions once every 30 seconds. Reduced agitation will increase adjacency effects, i.e. acutance. Rodinal has a single developing agent, para-aminophenol, which I prefer. Many developers, e.g. ID11/D76, while they are excellent developers of their type, contain two developing agents, one of which is often hydroquinone (quinol) which I consider too coarse for delicate higlight rendering. I suggest yo look up anything by the estimable Bob Schwalberg on the subject. You might also consider a developer using pyro, as the developing agent.

[bruce watson]

You are asking two questions that aren't closely related, I think.

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<i>What happens increasing agitation? Does this affect the characteristic curve exactly as increasing developing time or temperature, or does it work differently?</i>

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Many people have written books about what happens as agitation changes. Both Henry and Haist come to mind. IIRC, Henry didn't find a relationship between agitation and adjacency effects. Others, clearly, dispute that. For your purposes, I think you can assume that increasing agitation gives similar results as increasing developing time.

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<i>I'm searching a way to increase a little bit the midtone contrast, without affecting (too much) highlights.</i>

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I think what you are looking for here is a compensating effect. You can learn more about this from sources such as <i>The Film Developing Cookbook</i> by Anschel and Troop. You get compensation effects from accutance developers, often accompanyied by reduced agitation. Two part developers such as Diafine are compensating by their very nature. IIRC, water bath development is a compensating technique also.

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Lex is the local expert on these things. Perhaps he'll weigh in on this discussion...

[bruno]

Yes, I was also hoping in words from Lex... anyhow, I just had a short look at the "Film Developing Cookbook" on amazon, and ordered it... maybe I'll get also answers to questions I never did!

 

Thank you all, guys.

[StuartMoxham]

Just a bit of a guess you want to increase the midtones contrast but leave the highlights where they are. So in effect you want to steepen the straight the straight line part of the film curve but have the highlights roll gently off before blowing out. So how about increased development time with reduced agitation would that work. The Highlights may roll off because of the reduced agitation and you may get a bit more contrast in the mid tones. I would guess that it would also be depend on what developer type and dilution too. But this is just a guess.

[bruno]

So Stuart, I was thinking about reducing time and increasing agitation. But my assumption was based on nothing... I think you have quite a good take on this one... I'll try increasing a little bit time and reducing a little bit agitation and see if the changes start going in the right direction...

 

...I used to develope the old tri-x's a little bit more than Kodak suggested... should try the same with the new ones to see what happens... got quite a few rolls with nothing really important on them and it's a good chance for some tests.

[silent1]

Okay, this is from personal experience with TMY in HC-110 Dilution G:

 

If your developer is dilute enough to give a process time of about 15 minutes or longer, you can accomplish considerable control of contrast without affecting toe speed, by using a constant time/temp, and varying agitation. With the above combination and a process time of 15 minutes at 70 F, I can vary from a very flat negative with semi-stand development (agitate first full minute, then ten seconds at halfway through development only), somewhat flat with what Anchell & Troop call "extreme reduced agitation" (first full minute, ten seconds every five minutes thereafter), normal with "reduced agitation" (first full minute, then ten seconds every 3 minutes), to increased contrast with "standard" agitation (first full minute, then ten seconds every minute). I have no doubt that further increases in agitation (every 30 seconds or even constant agitation as in a rotary unit) would yield further increases in contrast, though I've had no need for more since to this point I've scanned my negatives and the scanner prefers lower contrast and lower maximum density.

 

This dilution may require extra developer volume above the minimum to cover 35 mm film in a stainless tank, however; you must observe the rule of using at least 3 ml of concentrate for every 80 square inches of film, and at 1:119, that means you need 360 ml for a single roll -- my stainless tanks need only 240 ml to cover 35 mm. This hasn't been a big issue for me because I shoot mostly 120, which takes 480 ml to cover.

 

You will always affect highlights by any change in contrast, however -- film speed is measured from the toe, which is the shadows in the subject scene; if you increase contrast without a change in process that reduces toe speed, you'll see the highlights gain density -- by definition. It is possible to compensate this effect somewhat, however, and highly dilute developers are key here, as well. Using reduced agitation and increased process time, combined with uprating the film slightly to account for the small increase in toe speed, you can take advantage of local exhaustion of dilute developer to prevent excessive development of highlights even while midtones are allowed to gain contrast through prolonged development. This would be in the "semi-stand" or "extreme reduced agitation" mentioned above; semi-stand, especially, tends to flatten the denser parts of the negative more than the shadows. Combine this with a further increase in process time and it should be possible to approach or even exceed normal mid-tone contrast without blocking up highlights.

 

However, if you really need to change the film's curve, you should consider simply changing films. Tri-X, for instance, has a steeper curve in the mid-tones and flattens in the highlights (in "standard" developers like D-76 and HC-110); TMY, by comparison, has a less steep midtone curve but much less (if any) flattening in the highlights. If you're not already shooting Tri-X or Plus-X, switching to those (or another "conventional" cubic-grain film) may give you exactly the mid-tone boost you need without having to change development significantly.

[bruno]

I use almost always TriX, exactly because I have a nice boost on the midtones, that fits exactly the subjects I want to shoot. I'd say that I'm already satisfied with my results, but I'm searching for a way to be even more satisfied!

 

I shot a couple of Tmax100 and they're so flat in the midtones, that the results are really awful (for me). I think they're good either for studio portraits or landscape/architecture stuff.

 

As developers I usually use XTol and ID11. XTol as stock most of the times, but a few times that I did 1+1, I'd say that the midtones are preserved while the highlights look a little bit more controlled... but the rolls were taken in such different light conditions that I cannot really tell :)

 

ID 11 1+1 gave me some flat results until now (ok, not SO flat)... but I think I did some underdevelopment there!

[henry_a]

Bruno,

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Try Tri-X rated at 200 - 320 in Xtol diluted 1:3 for about 10 - 12 minutes at 70 degrees F. For one roll you will need a tank that will hold at least 400 ml of working solution (so you are using at least 100ml of stock Xtol). Also you want some room in the tank for the developer to move. Agitate gently once a minute by just turning the tank over twice and sitting it back down.

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I have tried to prove that this will compensate or reduce highlight contrast but could not. I do feel that you can gain better control with the longer times and very consistently appllied minimal agitation.

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John Hicks has an article at unblinkingeye.com about rotary processing (constant agitation) and changes in developing times and film curves. You should read that.

[lex_jenkins]

Bruno, I've held back on responding to these threads until I have a chance to more carefully examine my next few rolls of film.

 

My impression from casually inspecting my negatives is that extending agitation and using continuous agitation produce essentially the same effect, or at least so close as to be practically indistinguishable.

 

However, Alexis Neel and others whose information I trust remind me that technically increased agitation increases contrast while increasing total development time increases negative density.

 

I generally use extended development time with normal agitation - compared with the usual available data - for negatives intended to be printing on my Durst M605. This has usually prodced the results I'm after.

 

The one time I tried continuous agitation for a shorter overall development time the results were disastrous. The negatives were practically black with barely distinguishable images. So I've been a bit hesitant to try again until I have time to try on a couple of unimportant test rolls.

 

Also, despite the hair-splitting that sometimes is waged over differences between gamma and contrast, most manufacturers of films and developers use the terms interchangeably or even combine the two. For example: "10 minutes, 30 seconds for gamma/contrast of .XX.)

 

There should be at least one or two threads in the archives on that specific topic.

[bruno]

Lex, I didn't want to go for such dramatic changes as you are suggesting. More I wanted a starting point for small changes: something like 10-20% more developing time and some agitation less versus a some 10-20% shortened developing time versus more agitation.

 

Even if I do something wrong, I should still obtain printable negatives... then, if the direction is right and the results not good enough yet, I might try to increase the differences.

 

Yes, I could switch to a higher paper grade and do some masking & burning... but sometimes it is really difficult (if not almost impossible) and time consuming to do it correctly... so I was wondering about the other possibilities.

 

Thanks for your hints.