metering & 18% grey

Discussion in 'Photography' started by tony, Jul 13, 2003.

  1. tony

    tony Guest

    greets all.
    been getting a little more "serious" with my camera
    and was hoping someone could clear up a question i have
    re: metering.

    NikonN65 in manual mode .. typical 75/25 centerweighted meter.

    taking a picture of a BLACK chair.
    (for arguments sake)...

    'measurements':

    a reading from the inside of my palm (dont have a grey card)
    the camera/meter reads: 1/30 @ f/4.5

    a reading from the back of the chair
    (black fills the frame): 1.5seconds @ f/4.5

    thats about 5 stops different!

    why are these so far apart? where is my
    mistake? which is the correct exposure?

    curve ball: in AperaturePriority
    the black chair reads 1/20 @ f/4.5
    ... why the one stop difference?

    cant figure out what MatrixMetering is reading
    because it INSISTS on using the flash.

    any ideas?
    thanks in advance.
    -tony
     
    tony, Jul 13, 2003
    #1
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  2. tony

    John O. Guest

    You've made no mistake. If the light falling on your gray card (palm) is
    the same as the light falling on the chair, then that is the correct
    exposure. If you meter something solid black, or solid white for that
    matter, your meter will try and make it 18% grey. That's its job.
    Relax... all is well.
    Probably using a different metering pattern. And don't meter the black.
    If you are in an auto mode, the camera will want to use flash when the
    shutter speed falls below about 1/60. Just meter the gray card.
     
    John O., Jul 13, 2003
    #2
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  3. This is EXACTLY what we would expect ...
    Take a look at this http://www.normankoren.com/zonesystem.html I hope it
    will explain it for you :)
     
    Not in my trousers, Jul 13, 2003
    #3
  4. tony

    Rudy Garcia Guest

    Assuming all the readings are taken with the same incident light:

    Your palm (if clean :) should read 1 stop over mid-tone. Therefore the
    more correct exposure based on your palm should be 1 stop more than the
    meter, or 1/15 @ f/4.5 . This is the reading you would have obtained
    with a grey card if you had one at the time.

    Why the black chair reads what it does? I don't know. I would have
    expected someting more like 2 or 3 stops from 1/15 @ f/4.5 .
     
    Rudy Garcia, Jul 13, 2003
    #4
  5. tony

    Paul Brecht Guest

    Paul Brecht, Jul 14, 2003
    #5
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