Confusions about using Kodak gray card

Discussion in 'Kodak' started by Steven Woody, Aug 17, 2003.

  1. Steven Woody

    Steven Woody Guest

    Q1:

    I want to calibrate my camera meter using a Kodak gray card.
    According to the instruction, I find that I have to use the card
    outdoor, but I dont understand why this is nessary. Why I can not use
    it indoor if I can guarantee the card dont reflect glare? And, I still
    dont understant why I can not use it under a full shade?

    Q2:

    Kodak ask me to open up 1/2 stop for the meter reading, I think this
    is due to that the 12.5% is used as natural reflectance by ANSI. But
    I doubt whether the 12.5% is really used by most camera vendors in the
    market. (I am using a Nikon F80, any know what the F80's viewpoint
    about netural reflectance).

    Q3:

    For copy work, Kodak suggest me to *close* down 1/2 stop for the gray
    card reading. That sounds so weird! What's the reason behind it?


    Any help would be appreciated!
     
    Steven Woody, Aug 17, 2003
    #1
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  2. Steven Woody

    Polytone Guest

    is it an 18% card?
     
    Polytone, Aug 17, 2003
    #2
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  3. Steven Woody

    snaps! Guest

    Indoors under incandesant or flouresent lighting, the light is a different
    *colour* to that outdoors and will alter the netural, 18% grey to something
    not predictable. In practice you can use it anywhere just so long as you
    have a TTL metering system because it measures light at (or near) the film
    plane. Hand held light meters using grey cards under anything other than
    daylight, might meter wrongly.

    Doug
     
    snaps!, Aug 17, 2003
    #3
  4. Let's step back a second. Why do you want to "calibrate my camera meter
    using a Kodak gray card"

    Generally I would advise using the same conditions that you will use the
    gray card after "calibration"

    The point is this. It would be very unusual for someone to need to have
    their camera calibrated to a standard. Much more usual to have their camera
    calibrated to their use.

    Don't assume that just because you are using the technically correct
    setting when taking a photograph that you will get the best exposure. You
    may get the technically correct exposure, but that may not create the best
    (meaning the best to you) image.

    Calibration is a good way for you to be able to closely recreate the
    exposure you want, but only if the calibration is based on the images you
    create.
     
    Joseph Meehan, Aug 17, 2003
    #4
  5. Steven Woody

    Tony Spadaro Guest

    The most important thing about using a grey card is to use it consistantly
    and take notes of the results you get, Experience is the real teacher here,
    the grey card is just an aid. All of Kodaks suggestions are just that -
    Suggestions.
    The difference between indoors and outdoors is the colour temperature
    of the light. You cannot assume that a reading taken with a grey card under
    flourescents will jibe with one taken under incandescents, or even that
    readings under one wattage of incandescent will work for other wattages.
    There are books written on exposure - the grey card is only one tool in
    your arsenel. Modern in camera meters are pretty accurate without any
    special work to boot. Get yourself a book on exposure from the library -- or
    a basic book with a good section on exposure, and take a look at the
    following article:
    http://www.chapelhillnoir.com/mani/techs/mgreywalk.html


    --
    http://www.chapelhillnoir.com
    home of The Camera-ist's Manifesto
    The Improved Links Pages are at
    http://www.chapelhillnoir.com/links/mlinks00.html
    New email - Contact on the Menyou page.
     
    Tony Spadaro, Aug 17, 2003
    #5
  6. Steven Woody

    Pierre L Guest

    In this context, calibration does not mean making any adjustments to the
    camera's meter. It merely means to take test shots using using the Kodak
    Grey card, and then based on the results, make whatever exposure
    compensation is necessary. It's basically a matter of getting to know your
    meter's behaviour.
    Pierre
     
    Pierre L, Aug 17, 2003
    #6
  7. Which means it should be done under the lighting conditions that the
    meter will be used in. One of the questions related to should it be done
    outside or inside and questions of type of lights. The answer is simple.
    Use the lighting situations you want to be your standard(s).

    Thanks for the clarification. I was guessing that as one possibility.

    --
    Joseph E. Meehan

    26 + 6 = 1 It's Irish Math


     
    Joseph Meehan, Aug 17, 2003
    #7
  8. Steven Woody

    Alan Browne Guest

    Hogwash! Use a grey card in any situation you like. I can never
    remember if green grass is less or more light than 18% grey. Or red
    shirts, or blue jeans or pink flowers...... The grey card, properly
    used, gives me accurate exposures every time without fail. It is most
    especially useful when shooting flowers as the riots of colors are
    anything *but* 18% grey in reflectance.
    Pigsweat. Use the grey card wherever you want.

    Cheers,
    Alan.
     
    Alan Browne, Aug 18, 2003
    #8
  9. Steven Woody

    Frank Pittel Guest

    Are you questioning the accuracy of the metering circuit in your camera??
    If so bring it to a local repair and have it checked out. I had a Canon
    that was off so much that it would over expose by three stops!! That's
    more then even print film can handle.


    : Q1:

    : I want to calibrate my camera meter using a Kodak gray card.
    : According to the instruction, I find that I have to use the card
    : outdoor, but I dont understand why this is nessary. Why I can not use
    : it indoor if I can guarantee the card dont reflect glare? And, I still
    : dont understant why I can not use it under a full shade?

    : Q2:

    : Kodak ask me to open up 1/2 stop for the meter reading, I think this
    : is due to that the 12.5% is used as natural reflectance by ANSI. But
    : I doubt whether the 12.5% is really used by most camera vendors in the
    : market. (I am using a Nikon F80, any know what the F80's viewpoint
    : about netural reflectance).

    : Q3:

    : For copy work, Kodak suggest me to *close* down 1/2 stop for the gray
    : card reading. That sounds so weird! What's the reason behind it?


    : Any help would be appreciated!



    --




    Keep working millions on welfare depend on you
     
    Frank Pittel, Aug 18, 2003
    #9
  10. It doesn't matter. Green grass gives an excellent basis for metering.
    Excuse me, who the hell has time for that?
    Average the ligher and darker ones. Bracket in cases of doubt.
     
    Michael Scarpitti, Aug 18, 2003
    #10
  11. Steven Woody

    Chris London Guest

    Hi Steven,

    The instructions probably say that because the easiest/most accurate way to
    calibrate your camera's meter is in bright sunlight, using the film
    manufacturer's recommended settings for bright sunlight (normally f/16 @
    1/125 for 100 iso film). Using your camera to meter the gray card in bright
    sunlight (ensuring you are not getting glare from the sun bouncing off the
    card toward you) is a good way to test your meter to see if it is reading
    the same as the film manufacturer recommends for the film. Some camera
    meters are off slightly (some by quite a bit from what I have read) from
    this standard, so this helps you 'calibrate' to see where your meter reads
    on this particular scale. You can then adjust your iso setting on the camera
    down or up to match the offset for the type of film you are using until it
    reads correctly, that way you don't have to calculate it into the meter
    readings later. This is one of John Shaw's recommendations in his books for
    handling metering issues. Although I have never had this happen to me, he
    writes that as high as 50% of his currently used cameras do not read f/16
    @1/125 in bright sunlight, and he is using some high-end gear (Nikon F4
    comes to mind).

    Once you have "calibrated", you can perform this same test without a gray
    card by metering off mid-tone objects you see around you in bright sunlight.
    They should give you similar readings, and this is also a good way to do
    some 'learning' to see what shades/colours are in fact mid-tone for those
    (seemingly quite frequent) occasions when a gray card is not available or
    feasible for shots.

    Personally, if my camera had not read "correctly" when I did the test, I
    would have taken it back to have the meter adjusted, simply because I
    wouldn't want to have to rely on more calculations than I absolutely need. I
    want to know I am starting at a set point and make my own adjustments from
    there.

    Hope this helps!

    --

    Cheers,
    Chris

    ***
    Atheism is a non-prophet organization.
     
    Chris London, Aug 18, 2003
    #11
  12. Steven Woody

    RDKirk Guest

    Unless a matrix or evaluative meter presumes the gray card is just a
    gray day and decides to up the exposure to compensate.


    --
    "To announce that there must be no criticism of the President,
    or that we are to stand by the President, right or wrong,
    is not only unpatriotic and servile,
    but is morally treasonable to the American public."

    Theodore Roosevelt
     
    RDKirk, Aug 20, 2003
    #12
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