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  1. #61
    Ian Grant's Avatar
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    Well put Jason, the amount of light needed to begin to fog a roll of 400 ISO film is very low so if your eyes spot light a minute or so after you turn the lights out trace the leaks and fix them.

    If you want to process 3200 ISO films then you really do need total black-out, which is usually not that difficult to achieve.

    Ian

  2. #62

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    Interesting Jason.....do you think that the light from a Gralab timer can fog film or paper?

  3. #63
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    Not in my experience, but my timer is out of line of sight (on a shelf with a lip above my trays). Exposure comes from both duration and intensity, so general speculations about abstract sources and situations aren't really useful.

    Testing is they key.

  4. #64
    Ian Grant's Avatar
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    Light from timers can and will fog films, and I've seen them fog colour papers.

    A friend couldn't eliminate a very slight greenish cast when he began RA-4 printing, it was a tiny red LED on a timer that was the culprit. B&W paper is far more forgiving.

    Ian

  5. #65

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    Another question Jason...the point regarding light in the darkroom also involves where the light is coming from. IF the light is coming in from the bottom of the door, and is rather faint....since light travels in a straight line, if the light is not bouncing off of anything bright, how can such light affect film on a table some feet above and to the side of the bottom of the door? I agree that total darkness is to be preferred, but nevertheless, it appears that since light does travel in a straight line that the risk of fogging film above the light leak should be rather minimal, or zero. I also agree that tests might be done to be certain. Not debating that Ralph's method of sealing light leaks can relatively easily be accomplished....however, some here have pointed out that minimal light leaks have NOT affected their work, such work having been carried out in the same darkroom for many years. Those individuals find no compelling reason to change the design of their work space-and one would, it seems, have to accept their opinions. Obviously no absolute right and wrong with reference to the discussion at hand....if it "ain't broke, why fix it"?

  6. #66
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    Inverse square law. When people say some timer light is fogging their paper, the first thing to ask is where the timer is placed. If it's sitting on the paper then, well, duh.
    "Only dead fish follow the stream"

    [APUG Portfolio] [APUG Blog] [Website]

  7. #67
    JBrunner's Avatar
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    Quote Originally Posted by Mahler_one View Post
    Another question Jason...the point regarding light in the darkroom also involves where the light is coming from. IF the light is coming in from the bottom of the door, and is rather faint....since light travels in a straight line, if the light is not bouncing off of anything bright, how can such light affect film on a table some feet above and to the side of the bottom of the door? I agree that total darkness is to be preferred, but nevertheless, it appears that since light does travel in a straight line that the risk of fogging film above the light leak should be rather minimal, or zero. I also agree that tests might be done to be certain. Not debating that Ralph's method of sealing light leaks can relatively easily be accomplished....however, some here have pointed out that minimal light leaks have NOT affected their work, such work having been carried out in the same darkroom for many years. Those individuals find no compelling reason to change the design of their work space-and one would, it seems, have to accept their opinions. Obviously no absolute right and wrong with reference to the discussion at hand....if it "ain't broke, why fix it"?
    Again a hypothetical. Too many variables. Even if I was present in the room I couldn't really tell you. Testing is the key. Working in a leaky darkroom and thinking that the leaks have no effect is much different than testing and knowing. Many a print lacks some of the subtle brilliance it could have, particularly in the very highest values, because of that kind of assumption (the assumption that there is no effect), and the photographer doesn't know the difference (perhaps for even for years) because he/she doesn't know the difference, but it can be the difference between a "10" and a print that goes to "11". I can't think of a single reason not to check, except for a lazy contempt for ones own work or sheer hard-headedness.
    Last edited by JBrunner; 01-11-2010 at 12:59 PM. Click to view previous post history.

  8. #68
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    Quote Originally Posted by Mahler_one View Post
    Another question Jason...the point regarding light in the darkroom also involves where the light is coming from. IF the light is coming in from the bottom of the door, and is rather faint....since light travels in a straight line, if the light is not bouncing off of anything bright, how can such light affect film on a table some feet above and to the side of the bottom of the door? I agree that total darkness is to be preferred, but nevertheless, it appears that since light does travel in a straight line that the risk of fogging film above the light leak should be rather minimal, or zero.
    Different Jason.. If you look down, and see light on your floor surface or on your shoes, from the leak at the bottom of the door, then light IS INDEED bouncing up to your eyes, which is further away than the film. Anything you see as illuminated is sending light in your direction.

    If you are loading a 35mm roll onto a reel at waist level, the film could be twice as close to the floor as your eye, and gets 4x as much light as your eye, due to the inverse square rule.

    Now, I know I can load a roll of iso400 onto a reel and put it in the tank very quickly and won't have any fogging even if light is leaking in. I'm sure I've loaded at least a thousand rolls over two decades. However, I still like it to be really dark. What if I knocked off the table the top of my tank? I could spend several minutes feeling around in the dark for it, and I don't want my film to suffer in the process.

  9. #69
    JBrunner's Avatar
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    Quote Originally Posted by jp498 View Post
    ...Now, I know I can load a roll of iso400 onto a reel and put it in the tank very quickly and won't have any fogging even if light is leaking in...

    Seriously, how do you know? Have you checked? Or is it just something you are printing through without knowing it is there? Film is less critical about overall fog because you can print through it, having a base+fog level to begin with even under perfect circumstance, so my real point is directed towards printing, but this "snip" I have inflicted on Jason's post (apologies) illustrates my point quite well.

    Nice to see another Jason!
    Last edited by JBrunner; 01-11-2010 at 01:24 PM. Click to view previous post history.

  10. #70
    Sirius Glass's Avatar
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    Quote Originally Posted by RalphLambrecht View Post
    I researched numerous papers and books on this subject and never found a totally consistent answer, but most agree on the following:

    The luminance range of the human eye is a combination of capabilities:

    1. iris 16:1 or 4 stops
    2. retina (static) 60:1 or 6 stops
    3. retina (dynamic) 1,000,000:1 or 20 stops

    This totals roughly 1,000,000,000:1 or 30 stops. Not 10 billion but 1 billion!



    You don't have to believe it, you can calculate it. If you can see an x-candela star from millions of light years away, from how far away can you see one candela? Now reduce this distance for atmospheric disturbances and... I'm too lazy to do it tonight.
    More more for the list.

    If the number of rods and cones were increased in our eyes, we would not see any better because the evolution of the resolution of the eye stopped when the evolution got to the diffraction limit of the eye.

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.



 

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