Gossen Sixtar meter needle

Discussion in 'UK Photography' started by D.M. Procida, Dec 4, 2010.

  1. D.M. Procida

    D.M. Procida Guest

    The needle on my Gossen Sixtar light meter is rather slow. Probably the
    oil on the pivots has become sticky - or maybe it's meant to have a very
    damped movement.

    How rapidly should the needle descend to zero in the absence of light?

    Daniele
     
    D.M. Procida, Dec 4, 2010
    #1
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  2. Dear Daniele,

    Am 04.12.2010 14:56, schrieb D.M. Procida:
    as far as I know, there is no "oil" in the ampere meter, a toe bearing
    is used, instead. The laggardness is a function of the Cadmium Sulfid
    Cells metering cell, used in this exposure meter, a characteristic trait
    for this type of metering cell. Therefore, the then revolutionary
    "Silicon Blue Cells" (SBC) were introduced, beeing much more responsive
    and sensitive. Cadmium Sulfit Cells (CdS) are also prone to glare. It is
    - however - very easy to produce a linear meter scaling from a CdS
    together with a constant voltage source, then often realised with a
    Mercury cell - a budget solution at the time of introduction. CdS cells
    do not suffer from degragation, as the older Selenium cells, which do
    not need an external power source in return. The real problem is the
    Mercury cell - You have to use a substitute, due to environmental
    legislation, now. One substitute is the "Wein" cell, quite expensive and
    only working for half a year after "activation". See

    http://www.smallbattery.company.org.uk/sbc_mrb625.htm

    for example! The alternative is altering the meter with a Zener diode to
    use standard cells, a task for an experienced technician. Otherwise -
    use a more modern meter...

    Slooooooowly, as explained above. The brighter the light, the longer it
    takes to reach zero position.
    Yours sincerely

    Christoph-Erdmann
     
    Christoph-Erdmann Pfeiler, Jan 20, 2011
    #2
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