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  1. #181
    Dave Pritchard's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Guys;

    You get away with no stop for film because film develops more slowly than paper and even when the rinse is bad, the resulting stains may not be easily seen. A print is developing rapidly when you put it into rinse water and you can quickly see stain or non-uniformity. But, just because you get away with it does not mean it is good.

    I have seen people use a tray of water as a "stop" for a whole printing session and wonder why their prints change from the start to the end of a session! Hello!!!! The water bath is becoming a developer due to carryover and even 30" in this alkaline bath changes the process. And, the carryover of byproducts into an alkaline fix makes the ammonia smell increase and actually slows fixing and allows development to continue.

    SO! If you use a rinse instead of a stop, and insist on using it, it MUST be running water. That is, unless you only intend to do 1 or 2 prints or one roll of film. Even that might be too much for some fixer/developer combinations!

    PE
    I agree for the most part. I use a water stop bath in a specific situation, though. My long-time preferred film and developer was Tech-Pan with dilute Rodinal. You probably know this story already. The contrasty film paired with a dilute developer worked nicely. Add the tale that the water stop allowed further shadow development, and I was hooked. It works well, too.

    I do not do this when using other film developers. I also religiously use a stop bath when developing paper prints.
    Last edited by Dave Pritchard; 07-20-2010 at 08:17 PM. Click to view previous post history. Reason: oops

  2. #182
    skyrick's Avatar
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    Efke says to use only water, no stop bath.

  3. #183
    Photo Engineer's Avatar
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    Quote Originally Posted by skyrick View Post
    Efke says to use only water, no stop bath.
    Go ahead and believe that.

    Then look at complaints here on APUG about products from various companies.

    Nuff said!

    PE

  4. #184
    Ian Grant's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Go ahead and believe that.

    Then look at complaints here on APUG about products from various companies.

    Nuff said!

    PE
    And people are still whingeing about Xtol, telling people how bad it is, sudden death scenario despite a small problem being solved years ago, and a great many of us having long trouble free use with it.


    John at J&C gave EFKE a bad name knowingly selling sub standard product, at a time when it looked like total collapse of the B&W market after Kodak's sudden pulling out of papers, Agfa ceasing, Ilford in restructuring etc.

    A great many people who use Adox/EFKE films never see a problem.

    Ian

  5. #185

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    Personally, I can't think of any reason to use an acid stop bath for film developing. As has been pointed out by many posters, based on their own experience, and in many cases based on direct comparisons between acid stop baths and water stop baths, water works just fine.

    Now let's think about this from a fundamental point of view. There have been comments that an acid stop bath produces instant arrest of developing. First, that comment is not quite true because it takes a little bit of time for the acid to be transported into the film. Furthermore, while this is happening the developer will be diffusing out of the film. This happens whether one is using acid stop bath or pure water. The time scale for the diffusion of developer out of the film is probably not much longer than the time scale for diffusion of acid into the film. My wild guess is that the diffusion rate of developer out of the film is probably within a factor four or so of the diffusion rate of acid into the film. (Any definitive information on this point would be helpful.)

    Since the time scales of the two processes (diffusion of acid in and diffusion of developer out) are likely on a comparable time scale, use of an acid stop bath is not likely to make much difference in the effective time for halting of development.

    Furthermore, there are at least two other process that will effectively stop the development of film. The first is that even with the use of pure water there will be a rapid change in the pH inside the film, resulting in a serious reduction in development rate. This will happen because hydroxide ions diffuse out of the emulsion. (I am assuming that the water is not highly alkaline.) The second is that developer trapped in the emulsion will be depleted by being used up, and it cannot be replenished by the bulk developer solution because the developer solution is not there any more.

    I do not know of any measurements, but all things considered I would be surprised if there were more than a few seconds difference in effective stop time using water vs. acid.

    However, the most important consideration is this. It is not important that development be stopped instantaneously. It is only important that the arresting of development be reproducible, and there is no physical reason that I can think of that would cause a water stop bath to be significantly less reproducible than an acid stop bath. Even if a water stop bath were less reproducible than an acid stop bath by a few seconds, that is not enough irreproducibility to make a noticeable difference in film development. My goodness, there are so many other sources of irreproducibility in film development that a few seconds of effective jitter aren't going to be noticeable.

    As a final comment, a water stop bath is the recommended method by the maker of one of the most reproducible automated film development systems, namely Photo-Therm.

    And now for a post-final comment. Acetic acid stinks, so I would rather not have it around. Non-stinky citric acid could be used, but why bother with the extra expense and fiddle factor when you can just use water?

  6. #186

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    One more comment. Unless I am mistaken, E6 uses a water stop bath, and E6 is far more finicky than black and white processing, so I don't think that irreproducibility of water stop baths can be a fundamental problem for black and white processing.

  7. #187

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    the portraitist i worked for used no stop, just water
    ( she was trained in the 20s/30s )
    i have a feeling the no stop bath movement has
    been around since before the 1970s ..
    i gave it up in the 90s ...

  8. #188
    JBrunner's Avatar
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    Quote Originally Posted by alanrockwood View Post
    Personally, I can't think of any reason to use an acid stop bath for film developing. As has been pointed out by many posters, based on their own experience, and in many cases based on direct comparisons between acid stop baths and water stop baths, water works just fine.

    Now let's think about this from a fundamental point of view. There have been comments that an acid stop bath produces instant arrest of developing. First, that comment is not quite true because it takes a little bit of time for the acid to be transported into the film. Furthermore, while this is happening the developer will be diffusing out of the film. This happens whether one is using acid stop bath or pure water. The time scale for the diffusion of developer out of the film is probably not much longer than the time scale for diffusion of acid into the film. My wild guess is that the diffusion rate of developer out of the film is probably within a factor four or so of the diffusion rate of acid into the film. (Any definitive information on this point would be helpful.)

    Since the time scales of the two processes (diffusion of acid in and diffusion of developer out) are likely on a comparable time scale, use of an acid stop bath is not likely to make much difference in the effective time for halting of development.

    Furthermore, there are at least two other process that will effectively stop the development of film. The first is that even with the use of pure water there will be a rapid change in the pH inside the film, resulting in a serious reduction in development rate. This will happen because hydroxide ions diffuse out of the emulsion. (I am assuming that the water is not highly alkaline.) The second is that developer trapped in the emulsion will be depleted by being used up, and it cannot be replenished by the bulk developer solution because the developer solution is not there any more.

    I do not know of any measurements, but all things considered I would be surprised if there were more than a few seconds difference in effective stop time using water vs. acid.

    However, the most important consideration is this. It is not important that development be stopped instantaneously. It is only important that the arresting of development be reproducible, and there is no physical reason that I can think of that would cause a water stop bath to be significantly less reproducible than an acid stop bath. Even if a water stop bath were less reproducible than an acid stop bath by a few seconds, that is not enough irreproducibility to make a noticeable difference in film development. My goodness, there are so many other sources of irreproducibility in film development that a few seconds of effective jitter aren't going to be noticeable.

    As a final comment, a water stop bath is the recommended method by the maker of one of the most reproducible automated film development systems, namely Photo-Therm.

    And now for a post-final comment. Acetic acid stinks, so I would rather not have it around. Non-stinky citric acid could be used, but why bother with the extra expense and fiddle factor when you can just use water?
    When using a water stop it is important that the stop not get loaded with developer, or during a long printing session it becomes a dilute developer solution. This places the load on the fixer and so on, so while I find a water stop to be effective and reliable, it is with the caveat that the water has to be running or changed frequently. I don't think I have had any better or worse results with an acid stop, and as a result I use water for simplicity, and because of all the smells I don't like, stop is at the top of the list. I wouldn't hesitate to recommend it, but nor would I say it is any better IMO. It's far more important to be consistent with procedure, than what you are using to arrest development IMO.

  9. #189
    Ian Grant's Avatar
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    Quote Originally Posted by jnanian View Post
    the portraitist i worked for used no stop, just water
    ( she was trained in the 20s/30s )
    i have a feeling the no stop bath movement has
    been around since before the 1970s ..
    i gave it up in the 90s ...
    No access to my 1890's Maunal of Photography (Ilford) or WWI copy but my 1910 Agfa data and this Ilord box from 1923 suggest a water rinse

    Quote Originally Posted by Michael R 1974 View Post
    I can't believe all this anti-stop bath nonsense lately
    So are we anti something that was once not recommended for films ? Ron Mowrey (PE) summed it up well. But modern films are much thinner so what worked in the 20's with far thicker emulsions must be OK now. We are talking fresh water. with prints that's too wasteful so stop-bath has long been recommended.

    I've boxes with similar instructions from other manufacturers as well

    Backs up what you're saying nicely John. Note the D23 - Ilford code indicating 1923 which was only dropped in the 90's - the box was marked 1923 & Rouen, France where the plates taken.

    Ian
    Attached Thumbnails Attached Thumbnails ilford_a.jpg   ilford_b.jpg  
    Last edited by Ian Grant; 07-21-2010 at 12:34 AM. Click to view previous post history. Reason: add

  10. #190
    fotch's Avatar
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    And more doctors smoke Camels. It was in print so it must be true.:rolleyes:
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