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  1. #61
    Ken Nadvornick's Avatar
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    Quote Originally Posted by Leigh B View Post
    Yes. I've used a Thomas Duplex in my darkroom for over 20 years with no adverse effects.

    That's why I questioned your results.
    Understood.

    But one does not need "skilled and trained technicians using calibrated equipment" to detect red, green or blue light. Afforded sufficient intensity, your eyes are already calibrated to do that. And I trust your skill—and honesty—to make that simple observation.

    When you performed the observation did you see any red, green or blue components in the overall output spectrum?

    I'm genuinely curious about this...

    Ken
    "Hate is an adolescent term used to stop discussion with people you disagree with. You can do better than that."
    —'blanksy', December 13, 2013

  2. #62
    Ken Nadvornick's Avatar
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    Leigh??

    The reason I'm asking is that for the last several years every time the topic of safelights has come up—and it's does so repeatedly as new people decide to start darkrooms—I have been giving this same advice for sodium and LED safelights. I am also acutely aware that APUG is an often used and excellent searchable reference for real-world information and advice. I use it frequently myself for this very purpose. So it becomes very important that the information and advice we all give is as accurate as possible.

    If someone should challenge me on some point because they think I may be wrong, or because they think they have a better solution, then it becomes my responsbility to revisit my conclusions to verify that I am not in error (which I did last evening by rechecking my Duplex before replying to you), or verify that their way is indeed better. And if I am wrong I must then raise my hand and correct my error to save people any possible grief (or wasted money) down the road.

    So... if your answer is that you observed and saw no other colors, then something else in my system may be causing me to be the outlier and I must find out what that is and probably revisit my standard safelight advice. I do realize that my observations have taken place on only a single discharge tube.

    But if your answer is that you observed and can confirm my observations, then you, me and Professor Niece make three concurring results and therefore increase the chances that the effect is more general in nature, and that the standard advice need not be revisited and is still worth taking.

    It basically just boils down to integrity.

    Ken
    "Hate is an adolescent term used to stop discussion with people you disagree with. You can do better than that."
    —'blanksy', December 13, 2013

  3. #63
    Leigh B's Avatar
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    Hi Ken,

    No, I did not do the test that you described in #51.
    I don't use the safelight without the filters installed, so the results would be irrelevant.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  4. #64
    Ken Nadvornick's Avatar
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    I thought you did, based on your direct answer in #58 to my direct question in #57. Sorry, my mistake.

    Could you try it for me, please?

    It takes only a couple of minutes. Testing without any filters will factor out the effects of filters that are old, faulty, incorrect, or recycled. In other words, if there is no green or blue light emanating from the bare bulb to begin with, then there can be no safelight-induced paper fogging by that mechanism. Unless the sensitizing dyes in the paper are faulty, and I'm guessing that's not the case.

    This information would be of direct value to new darkroom workers considering a Duplex, since these safelights are now discontinued and only used ones are generally available on the market.

    It really is a very, very quick and easy visual check.

    Thanks Leigh,

    Ken
    Last edited by Ken Nadvornick; 09-09-2012 at 12:32 PM. Click to view previous post history. Reason: Clarity...
    "Hate is an adolescent term used to stop discussion with people you disagree with. You can do better than that."
    —'blanksy', December 13, 2013

  5. #65
    Leigh B's Avatar
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    Ken,

    I will not do the test as described because...
    1) The light is not used with the filters removed, so the results would be meaningless; and
    2) The safelight is mounted to the ceiling in an area that is not readily accessible without removing cabinetry and plumbing,
    so removing and re-installing the internal filter would take most of a day.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  6. #66
    Ken Nadvornick's Avatar
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    Quote Originally Posted by Leigh B View Post
    I will not do the test as described because...
    Or...

    3) You already did the test and can't bring yourself to raise your hand and talk about what you saw.

    (Your Duplex looks very easily accessible here. The pull chain for the adjustable vanes is visible at the top, just right of center. No surrounding cabinets or plumbing appear to need removing at all. But I guess you have your reasons. Or will now find some new ones.)

    And so with your above flat out refusal to supply any observations to the contrary to support your challenge, my original observation regarding the fogging tendencies of LPS tubes, and my workaround advice to mitigate that fogging, stands.

    Sadly, you and I have been down this road before.

    Ken
    "Hate is an adolescent term used to stop discussion with people you disagree with. You can do better than that."
    —'blanksy', December 13, 2013

  7. #67
    Leigh B's Avatar
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    How dare you call me a liar, asshole.

    You're not worth a lie.
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  8. #68
    Ken Nadvornick's Avatar
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    Nevertheless, it is what it is.

    I gave you every opportunity to back up your snarky challenge, and you wouldn't—or couldn't—do it. Even carved out a face-saving context for you retreat into, if need be. Now you're trying to shift the subject into something where you're the victim? Sorry. Perhaps a nice technique in formal debates or political discourse, but it won't work in this context. Facts are, sometimes inconveniently, facts.

    My characterizations stand.

    And my apologies for this mess to anyone still following this thread. I really did try to take the high road and give every benefit of the doubt. But trying to engage intellectually with some people is like trying to clean up spilled mercury with a fork. Very very frustrating, and in the end not much gets accomplished anyway.

    (You may have the last word, if you feel you need it. Please try not to make it foul-mouthed...)

    Ken

    P.S. As I was typing this I received a PM from another APUG individual. I won't identify that individual, but here is a quote (see chart #S8 at the bottom of the linked page):

    "If you look at this image, you can see a small green and blue component, as well as a moderate red spike in the IR region:

    http://www.lamptech.co.uk/Documents/SO%20Spectral.htm

    These probably derive from the neon and argon gas which are included in the tube to help start it up. From my own experience with low pressure Na tubes, they definitely start with a pinkish/purple glow. I've also examined the lamps with a diffraction grating and spectroscope, and have seen green and blue emission lines, as well as the sodium doublet."

    Please note that final sentence. It is what it is, Leigh...
    Last edited by Ken Nadvornick; 09-09-2012 at 05:19 PM. Click to view previous post history. Reason: Per author request, corrected instrument type in PM quote...
    "Hate is an adolescent term used to stop discussion with people you disagree with. You can do better than that."
    —'blanksy', December 13, 2013

  9. #69
    polyglot's Avatar
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    Quote Originally Posted by Leigh B View Post
    Absolutely true.

    That's why the references I gave were real-world tests run in laboratories under controlled conditions, by
    skilled and trained technicians using calibrated equipment.

    Not their eyeballs in a basement.

    - Leigh
    You're talking about perfect sodium emissions, not Thomas Safelight emissions. Clearly (from the multiple independent observations of several other strong lines) it's likely that the Thomas bulbs have more than just sodium in them, e.g. due to contamination while filling or other gases used to permit easier starting.

    If an eyeball in a basement can observe the additional lines, they've got to be pretty significant in magnitude.

  10. #70

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    Proper Safelights

    Have we really defined the "proper" safelight?

    I used a couple of 0C Kodak safelight (standard 5.5") for years, until I took John Wimberley's darkroom workshop. He's ADAMANT about stray light in his darkroom and preventing any fogging whatsoever of highlights. He tested the OC filters, and they failed. (I think that his tested is related to the one described by A.A.)

    The Red Series 1 Kodak filters passed his test, so that's what he uses. I followed his recommendation and replaced the OC's I've been using.

    With that said, purchasing these new is expensive. I waited until two Series 1's became available on EBay for modest prices. They don't come up that often.

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