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  1. #1
    David Lyga's Avatar
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    another way to ponder 'intermittent' agitation

    Although some of us agitate film continuously, most of us do so intermittently in the developer. We are told to agitate 'every 30 seconds', 'every 60 seconds', or other inventive ways. Maybe a better, more rational approach would be to space agitations according to how long development time is.

    My theory is this: with long development times it takes a proportionally longer time to exhaust developer at the specific location it is on the film. This local exhaustion necessitates refreshing that developer with 'new' developer, and that is done through agitation. If development time is really short that means that the developer is working very quickly and, thus, exhausts rapidly.

    Why not, instead of 'standardized' agitation intervals, simply divide the TOTAL development time by a factor of, say, 10, and base those agitation intervals upon that? For a 10 minute development time that would mean we agitate every minute. For a five minute development time that means that we would agitate every 30 seconds, and so forth.

    At least to me, this would seem to result in a negative process that more closely conforms to the ACTUAL capacity of the developer and respects that developer's ability to reduce silver in a standardized way, regardless of the speed (and inherent contrast) of the negative material it processes. And it simplifies much: from now on ALL films get 'ten agitations'. - David Lyga
    Last edited by David Lyga; 04-12-2013 at 09:28 AM. Click to view previous post history.

  2. #2
    Laurent's Avatar
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    Others, more expert than me, will react to this, but the first thought this brings to my mind is that, when times are longer it is -usually, at least for me- because dilution is higher, therefore exhaustion would be faster and the timed agitation could make sense.
    Laurent

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  3. #3

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    David - it also depends on the film and developer. Remember that the purpose of agitation is not only to replenish exhausted developer, but also to remove development by-products that can lead to streaking and other problems depending on the developing agents present, pH, film type.

  4. #4
    Richard Sintchak (rich815)'s Avatar
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    another way to ponder 'intermittent' agitation

    I just do it one way, and stick to it for consistency, then adjust my other variables as needed. There's enough other stuff to over-think. I think.
    -----------------------

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  5. #5
    Kevin Kehler's Avatar
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    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. which is why reducing or increasing developing times has a strong influence on highlights and contrast as these are the areas that need the most development time. So, while I understand what you are trying to do, I suspect you would have incomplete highlight/contrast development under your theory.

    Just my opinion, I am sure there are more scientific answers.
    Once a photographer is convinced that the camera can lie and that, strictly speaking, the vast majority of photographs are "camera lies," inasmuch as they tell only part of a story or tell it in a distorted form, half the battle is won. Once he has conceded that photography is not a "naturalistic" medium of rendition and that striving for "naturalism" in a photograph is futile, he can turn his attention to using a camera to make more effective pictures.

    Andreas Feininger

  6. #6
    kintatsu's Avatar
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    Rather than rely on some formulaic method of agitation, one should probably rely on the actual contents of the negative to determine agitation. With decreased agitation, separation between high and low values is decreased. The opposite is true for increased agitation. With higher values, the developer exhausts quicker than with lower values, therefore your development and agitation should be matched to some context of the individual scenes. By altering your agitation, as with altering your times, you change the range of values. The greater the alteration, the greater the change. As agitation is only part of it, I should think there is no magic one size fits all.

    I have found that changing agitation to match my scenes gives me better pictures than using a solid set in stone standard.

  7. #7
    cliveh's Avatar
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    I don’t follow this theory at all. Some of us want complete consistency of method. There are enough variables within photographic capture and processing without increasing them.

    “The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”

    Francis Bacon

  8. #8
    kintatsu's Avatar
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    Generally speaking, standard agitation, tested for each film, is correct. Consistency is the key, but to achieve results consistently may require trading consistent methodology for something more likely to produce the consistent results we desire. That's why we have expansion and contraction, and other methods of obtaining the final print we want.

    Decreasing, or increasing, agitation just to have some mathematical formula seems to defeat the purpose of controlling the values we wish to present in our print. It can't work if it's based only on some formula, as each scene with values that deviate from the photographer's mathematical norm will likely be a disappointment. That's why we test and create a system that works for us.

    The point I was trying to make was that using just mathematical numbers and formulas without consideration of values and subject just doesn't seem a good idea.

    These comments are only based upon my own experience and study, which is limited, so please don't think I'm trying to offend anyone, and if I did, I apologize.

  9. #9
    David Lyga's Avatar
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    Maybe I will learn something new here.

    I honestly thought that all chemical reactions slowed down with a developer/film combination that required long development. Take, for example, D-23 with Tri-X at 68F: it takes 'forever' to achieve adequate contrast. So, I thought logically, that agitation with that combination should be about every two or three minutes, with a total development time of 20 to 30 minutes. Or take HC-110 using a rather active dilution of 'B', with Pan F: Maybe less than five minutes, total, would be adequate for such development (achieving same gamma), and, with that combination, agitation at least every 30 seconds would become mandatory for complete freedom from possible inconsistency.

    kintatsu posits that separation between high and low values is decreased with less agitation. That is true in an absolute sense, of course, but not necessarily true in the two relative senses I pose above. With long, long development times I don't think that 'every 30 seconds' achieves any greater separation than with 'every two or three minutes'. Why? Because with slow development the developer reducing the highlight area remains just as strong as the developer reducing the less taxing shadow areas for a lot longer time. Thus, there is no exhausted developer to replace (yet). But with the fast development for Pan F and HC-110, the exhaustion takes place far more rapidly, thus agitaion must be far more frequent.

    Regardless, maybe I am incorrect; your diverging viewpoints are certainly welcomed. Sometimes that which seems logical proves to be misguided when others offer better reasons. - David Lyga
    Last edited by David Lyga; 04-12-2013 at 04:36 PM. Click to view previous post history.

  10. #10
    cliveh's Avatar
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    Quote Originally Posted by kintatsu View Post
    Consistency is the key, but to achieve results consistently may require trading consistent methodology for something more likely to produce the consistent results we desire. That's why we have expansion and contraction, and other methods of obtaining the final print we want.
    I don't see this as a trade off. Please explain.

    “The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”

    Francis Bacon

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