Another count for lights on when the film is in the stop bath. As an experiment with paper you can turn the light on when its in dev, and watch it darken, then move it to the stop and watch it immediately stop darkening, quite interesting.
Another count for lights on when the film is in the stop bath. As an experiment with paper you can turn the light on when its in dev, and watch it darken, then move it to the stop and watch it immediately stop darkening, quite interesting.
Not sure about turn lights on when the film is in the stop bath, if it is not strong enough some residual development could take place, if it is too strong stop can react with developer accelerators (bases) to cause damage to the film. A lot of folks on this list seem to use a water bath rather than an acetic acid stop bath, in that case don't turn on the lights.
I have generally waited until the fix is finished when using a tank, 30 seconds to one minute in fix when using trays. Really think the safest is to wait until the fix has done some action. BTW I have turned on the lights while paper is in the stop (acetic acid) and gotten some fogging.
Tom
Stop bath takes time to do it's thing. It's not an instant process. If your instructions say to have it in the stop for 30 second, it's because it might need 30 seconds to totally stop the development (remove or neutralize the developer).
I know I've turned the lights on with test strips of paper freshly put into the stop bath and seen ghostly darkening of the strip because of the lights coming on while it sat in the stop bath. This is a more telling experiment than JRFrench's still interesting test.
For paper, I am comfortable turning the lights on 15 seconds after it's in the fixer. For film, I'm comfortable after 2-3 minutes of fixing.
I prefer to not take chances with film, I'd suggest waiting to turn on any lights until the fixer step is complete - full recommended length of time.
Thanks,
Dan
"After development the negative is transferred to a stop bath, which serves several functions: (1) since it is acidic, it neutralizes the alkaline developer remaining in the emulsion, thus immediately arresting development. . . . " (emphasis added) Adams, "The Negative" p. 190. He then goes on to discuss the purpose of the fix, which isn't to further stop development (since the stop bath has already accomplished that) but rather is to remove unreduced silver halide remaining in the film after development which if not removed would eventually cause staining or bleaching of the film.
If those who wait until film hits the fix or has been in the fix for some time before turning on the lights feel more comfortable doing that, that's certainly fine for you and I wouldn't try to change your practice. But the OP shouldn't be mislead into thinking that it's necessary or even useful to wait that long. I turned on the darkroom lights as soon as the film hit the stop bath for many years because I never liked standing around in the dark and have never had any problems from doing that.
Brian Ellis
Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
a mile away and you'll have their shoes.
This.Originally Posted by DanK
What's the rush? If you can't wait a couple of minutes to see your negatives then you may not have the patience for LF photography.
I do tray development and I switch on the light after 2 minutes of continuous agitation in the fix. I do not agree with the suggestion that the film can be exposed after the stop. Stop stops the action of the developer on the chemicals (that have been exposed to the light) and that does not mean that all of the silver on the film has become light insensitive. Fixing takes care of the remaining silver that is sensitive to the light by removing it off the film. Hence I believe that at least a few minutes in the fixer (3 minute minimum is suggested by Ilford for its rapid fixer) is a must before the film is exposed. As for the safe light, one must take the film sensitivity into consideration. High iso films are not safe with safe light. While most print papers and films like EFke 25 do not mind the safe light.
I wait until 3 minutes into a five minute fix. What's the rush? And at that time I'm SURE it's safe.
Bruce Barlow
author of "Finely Focused" and "Exercises in Photographic Composition"
www.brucewbarlow.com
Develop 4 4x5 sheets of paper of an identically exposed high key image. Drop each into the stop bath at 3 second intervals, then immediately turn the lights on. That will show you it is certainly not an instantaneous process to stop development with stop bath. The last couple of sheets will get a dark shadow on them as the developer hasn't been neutralized yet.
Fixing removes unreduced silver halides (i.e. the silver halide crystals that weren't reduced to metallic silver by the developer) that remain in the film emulsion after development. If these halides weren't removed they would, over a relatively long period of time, cause stains or bleaching in the film. But the halide crystals that have already been converted to metallic silver (i.e. the image forming crystals) are no longer affected by light once development is arrested by the stop bath, i.e. metallic silver is metallic silver, it doesn't become any "more" metallic silver by exposure to light after that point. And even the staining or bleaching that fix prevents isn't going to happen in the few seconds of exposure to light that occurs while the film is in the stop bath.
So no, a few minutes in the fixer before turning on the lights isn't a "must." If it was I would have ruined at least a thousand sheets of film.
Brian Ellis
Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
a mile away and you'll have their shoes.
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