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Dull lume?

Discussion in 'Watches' started by crazysgt, May 1, 2017.

  1. Narcosynthesis

    Narcosynthesis Loaded Pockets

    Jul 21, 2009
    Likes Received:
    I feel I should sit on the fence and add a couple of comments here...

    The half life of tritium is an indisputable fact - after 12.3 years, the tritium gas held within a vile will be emitting exactly half the radiation as it did when new. So the vials will dull over time - note that if you look at items like the tritium powered exit/emergency signs, they are sold based on the lifespan of the tritium.

    However, not all tritium vials are created equally - different sizes, different phosphors (the bit that actually does the glowing), and different amounts/pressure of gas within will all change the output. So comparing two items will be very hard given the timespan between their manufacture.

    I would hazard a guess that if you are comparing a 20 year old watch with a brand new one, it is entirely possible that they are of an equal brightness - but this will also come with the note that the 20 year old watch probably had brighter markers when it was new than your new watch does.

    To go alongside this, I have compared multiple 23x3mm tritium vials against each other - different colours are of noticeably different output, but also two theoretically identical green tubes had different outputs, so there definitely can be a change - as I noted above though, as I didn't get them both from the same place at the same time, I couldn't say whether the one I know was secondhand was a few months or ten years old, or when exactly the ones I have bought new were manufactured, so whether the difference was ageing or another factor I do not know.
    #21 Narcosynthesis, May 4, 2017
    Last edited: May 5, 2017
    Moshe ben David likes this.
  2. tirod

    tirod Loaded Pockets

    Sep 20, 2006
    Likes Received:
    One of the more important elements of assessing "brightness" is the fact that the human eye adjusts by opening the retina and also the rods and cones over a period of time. What you can see going from a brightly lit room into a dark one to check the luminosity of a dial will be different at 4AM waking up in a dark room.

    Everybody talks about the tubes but nobody that their eyes adjust - proven fact - and that we see things differently from broad daylight vs long term darkness. This human trait is exploited in the military by having soldiers who are scheduled for night patrols to remain in darkness before sundown to accelerate the acclimatization of sight, and is even part and parcel of Vietnam war lore as some soldiers were reputedly staying out of sunlight their entire tour to retain and enhance their night vision.

    It is a thing and it does exist. If you don't account for it when viewing your watches it then becomes a significant factor in how you see them.

    Another factor is that certain colors have more impact on the retina and are seen more readily. This is why there is a push toward green lasers vs red. Although the green colorway is much less efficient technically, the human eye sees it more readily and users are willing to trade off battery life for the "brighter" sighting point.

    Search the internet and you will find published photos and charts by manufacturers and owners for all this, it's open book.
    aladan likes this.