Pentax Color Refectance Chart

Discussion in 'Exposure Discussion' started by hortense, Nov 16, 2006.

  1. hortense

    hortense Member

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    Old one that was Zone VI Studios corrected was stolen. Can anyone help me understand how to use this chart?
    Thanks in advance.

    PENTAX DIGITAL SPOTMETER
    LIGHT REFLECTANCE OF SEVEN COLORS
    Color[/U]……Reflectance, %.....EV Index No.
    Red, bright………………15-21 …………..........……5
    Orange…………………..35-45…………...............…6-7
    Yellow, dark……………65-75………………...............8
    Green, dark leaf………….18-26………….........…Standard
    Blue………………………15-21……….................…….5
    Indigo and purple…………6-12……………2-3
     
  2. Mike Wilde

    Mike Wilde Member

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    not definitive, but some thoughts

    The colours are all interpreted by the spot meter as grey (at 18% reflectance) is my understanding, and the meter wants to expose them as grey. Your card indicates the typical ramge of reflectance of the color in question in the first column.

    The second column I believe is somewhat un-related. It says to me to meter something with that color, measure it, but then instead of using the exposure that dials up for zone 5, use the exposure that lines up for the exposure zone given.

    This makes sense on my analog spot meter. I am not sure how you tell the digital spot meter that you basically want to dial in an EV correction to adjust the exposure up or down a few zones. On my analog meter I just turn the dial to put zone 3 at the needle reading value, instead of zone 5, as an example.

    I use a colour swatch out of an old kodak data guide as my test card. It does not have the range of colors as say a macbeth colorchecker, but mine came from the used bin at$3, rather than the $80 or so that the macbeths seem to always go for.
     
  3. Kirk Keyes

    Kirk Keyes Member

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    That second column is not EV values - they are IRE values used for Television work. THey are not one f-stop apart as zones are, but they range from 0 to 10 in about 5 stops. THey are very useful for working with color transparencies.

    Read this thread: http://photo.net/bboard/q-and-a-fetch-msg?msg_id=003Eap
     
  4. hortense

    hortense Member

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    IRE vs. Zone system

    Kirk,
    Thank you for your help. I now understand that IRE is not for my kind of photography. Pentax V manual did not make distinction between cine and my kind of camera. However, I suspect that someone with more experience than me would find some useful information in the chart to improve spotmeter reading various colored objects (e.g., green foliage) that I wish to present as a black an white image.