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  1. #11
    Bill Burk's Avatar
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    Quote Originally Posted by pentaxuser View Post
    If I have got this right then what is the irreversible chemical action that prevents further development?
    In the case of acid stop, I get the feeling what happens is the pH changes so development activity is quickly reduced. You could rinse the film off and put it back in the developer if you wanted to. But if you had turned on the lights, it would start to turn black (you would get Sabbattier effect which is pretty cool).

    In fact a few weeks ago I accidentally dropped a sheet of film in the stop first by mistake. Still in the dark, I quickly realized the mistake and pulled it out and dumped it in a bucket of water I had handy. Then I went on to develop it normally and you can not tell the difference. Stop bath didn't cause irreversible change.

  2. #12

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    Quote Originally Posted by Bill Burk View Post
    . You could rinse the film off and put it back in the developer if you wanted to. But if you had turned on the lights, it would start to turn black (you would get Sabbattier effect which is pretty cool).

    .
    Thanks Bill. So the correct light by itself(i.e. not daylight or fluorescent) changes nothing as long as it is then fixed. It is the combination of light and further developer. The stop only "stops" as long as it is dark or if in light fixer is then applied. Using stop be it water or acid does not prevent the process being continued as long as the film has remained in the dark. If the processor suddenly realises that the dev time was wrong he/she can continue. Nothing is lost. Most here might realise this but others might think that there is no hope if stop has been applied and end up with an underdeveloped film which could have been saved.

    However there is no "free lunch" and no question of being able to check film in light and then continuing development other than the very dim green light approach which might work if you had lots of experience of checking film under such light.

    The maris approach would save the waste of fixer in the case of light leaks as the OP mentions but have no other benefits as far as I can see.

    pentaxuser

  3. #13
    Bill Burk's Avatar
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    Quote Originally Posted by pentaxuser View Post
    ... other than the very dim green light approach which might work if you had lots of experience of checking film under such light.
    ...

    The maris approach would save the waste of fixer in the case of light leaks as the OP mentions but have no other benefits as far as I can see.
    Very dim green light will reveal obvious issues like a neg where the flash didn't go off (or you might recognize an interior shot you expected would be underexposed)... Then you can know to develop longer to have a chance to get a print.

    Infrared viewers are really cool for the same reason.

    The maris approach is great to show mastery over the darkroom.

    But there is a practical reason to understand if some light (like from a 40 watt bulb) can safely shine on film, after developing right when film goes in the stop bath.

    BTZS tubes are designed to be used that way, and many people report they don't have any problem with fog or Sabattier effect. I originally took the position it was safe, but was corrected by a scientist who explained that the process should be tested with alkaline fixers before saying it is safe for everybody.

  4. #14

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    as cliveh and bill say a green safelight works wonders to develop by inspection.
    the dark green filter is dark enough that with room light on
    you can barely see it is on
    but in darkness, when your pupils are BIG you can see pretty well with the safelight.
    i DBI often ... its kind of fun too ..
    im empty, good luck

  5. #15
    Andrew O'Neill's Avatar
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    After 1 minute in the fix (rapid fix), I turn the lights on.

  6. #16
    Bill Burk's Avatar
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    Quote Originally Posted by Andrew O'Neill View Post
    After 1 minute in the fix (rapid fix), I turn the lights on.
    One day my tempering bath overflowed into the last 16 ounces of fix I had. I caught it but not before the water had seriously diluted my fix. I had to fix that batch of film for 20 minutes. Lucky I had my IR scope and could tell the film wasn't clearing.

  7. #17

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    Quote Originally Posted by puketronic View Post
    I want to check purely for light leaks/lens sharpness,
    What seems to have gotten lost in this discussion is that fact that you cannot check for lens sharpness with an unfixed negative. This is because the undissolved silver halide will obscure any fine detail. In fact the negative must be fixed, washed and dried before lens sharpness can be quantitively determined.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  8. #18
    Bob Carnie's Avatar
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    I look at 8x 10 negs seconds after going into the fix when I am doing solarizations.. I want to see the black line and then move on to the next set of negs and work through an afternoon this way.
    I have seen no issues with the film. It freaked me out the first time trying this but I use an acid bath and within ten seconds the film clears out so I can see it..

  9. #19

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    Quote Originally Posted by Bill Burk View Post
    But there is a practical reason to understand if some light (like from a 40 watt bulb) can safely shine on film, after developing right when film goes in the stop bath.

    BTZS tubes are designed to be used that way, and many people report they don't have any problem with fog or Sabattier effect. I originally took the position it was safe, but was corrected by a scientist who explained that the process should be tested with alkaline fixers before saying it is safe for everybody.
    I am confused again Bill. Are you saying that BTZS tubes allow the very thing that I had concluded was impossible based on your explanation, namely the ability to examine negs after developer under a 40 watt bulb and then presumably to safely increase development if required?

    Thanks

    pentaxuser

  10. #20
    cliveh's Avatar
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    No, usually an acid stop bath is used that neutralises an alkaline developer, but silver halide remains that is still sensitive to light. Water is usually pH neutral. The fixer (usually acidic) dissolves the unexposed silver halide making the image fixed.

    “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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