Calibrating a light meter.

Discussion in 'Exposure Discussion' started by Mike Kennedy, Aug 26, 2006.

  1. Mike Kennedy

    Mike Kennedy Member

    Messages:
    1,595
    Joined:
    Feb 5, 2005
    Location:
    Eastern Cana
    Shooter:
    Multi Format
    I just picked up an old Vivitar No.30 for $2.00. It responds to light so I know the cell isn't fried . I plan on testing it against my FM2 and a grey card.
    Question: If it's out of wack how can I adjust the meter (no screw)?
    Would I simply tune the iso setting until it reads the same as my Nikon for Tri-X ?

    Thanks,
    Mike
     
  2. resummerfield

    resummerfield Subscriber

    Messages:
    1,362
    Joined:
    Jan 28, 2005
    Location:
    Alaska
    Shooter:
    Multi Format
    That's how I would do it, and keep notes of various ISO settings.
     
  3. MattKing

    MattKing Subscriber

    Messages:
    17,043
    Joined:
    Apr 24, 2005
    Location:
    Delta, BC, Canada
    Shooter:
    Multi Format
    Try it as well at a variety of light levels. Sometimes, when meters go out of whack, they become non linear. It could happen that it is 1 stop out at EV 4, but 3 stops out at EV 11.

    If it is consistently out by the same amount, then you can just dial in the correction.

    One further note - experiment with the position of the meter until you get a good appreciation of the angle of acceptance.

    IIRC the very first hand meter I ever owned was a Vivitar 30 - I think I traded it in for my Gossen Profisix.

    Matt