How to make a grey card?

Discussion in 'Digital Photography' started by My View, Apr 1, 2006.

  1. My View

    My View Guest

    Any suggestions on how to make an accurate grey card?
    regards
    PeterH
     
    My View, Apr 1, 2006
    #1
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  2. My View

    My View Guest

    In my search on the internet I came across this article - any thoughts?

    Also, if I make a homemade grey card what is the best way to test that it is
    correct form my 300D camera?

    I presume one way is to get the camera histogram to spike at the midpoint.


    "My View" <no spam > wrote in message
    news:YujXf.20985$...
    > Any suggestions on how to make an accurate grey card?
    > regards
    > PeterH
    >
     
    My View, Apr 1, 2006
    #2
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  3. My View

    My View Guest

    this is the article http://www.bythom.com/graycards.htm



    "My View" <no spam > wrote in message
    news:KBjXf.20990$...
    > In my search on the internet I came across this article - any thoughts?
    >
    > Also, if I make a homemade grey card what is the best way to test that it
    > is correct form my 300D camera?
    >
    > I presume one way is to get the camera histogram to spike at the midpoint.
    >
    >
    > "My View" <no spam > wrote in message
    > news:YujXf.20985$...
    >> Any suggestions on how to make an accurate grey card?
    >> regards
    >> PeterH
    >>

    >
    >
     
    My View, Apr 1, 2006
    #3
  4. My View

    Tony Polson Guest

    Tony Polson, Apr 1, 2006
    #4
  5. My View

    Taswolf Guest

    "My View" <no spam > wrote in message
    news:7CjXf.20992$...
    > this is the article http://www.bythom.com/graycards.htm
    >
    >
    >
    > "My View" <no spam > wrote in message
    > news:KBjXf.20990$...
    >> In my search on the internet I came across this article - any thoughts?
    >>
    >> Also, if I make a homemade grey card what is the best way to test that it
    >> is correct form my 300D camera?
    >>
    >> I presume one way is to get the camera histogram to spike at the
    >> midpoint.
    >>
    >>
    >> "My View" <no spam > wrote in message
    >> news:YujXf.20985$...
    >>> Any suggestions on how to make an accurate grey card?
    >>> regards
    >>> PeterH
    >>>

    I bought an 18% grey card from my local photography shop and when I
    photograph it, my histogram on my 350D shows a nice spike right smack dab
    in the middle. Card cost me about $5 I think....

    T.W.
     
    Taswolf, Apr 1, 2006
    #5
  6. My View

    kctan Guest

    There is no such thing as accurate grey card and you don't need a grey card
    when you measure the incident light for exposure. Grey card is for reflected
    light exposure measurement like the one in your 300D. This meter will see
    light as a mixing "glow" of light reflected from the scene. So subject
    against dark background and subject against light background will give
    different reading due to different "average" reflectance. So a standard
    reference in between is created and this is the grey. 12% or 14% or 18%
    doesn't matter as long as it is the mid average because usually picture
    taken belong to this kind of scene. Therefore if you think that the scene is
    too much in light tones (snow scene), compensate a "+" with exposure
    compensation function when using auto exposure mode or vice versa. If your
    scene match the reference grey after averaging, exposure usually is good. If
    you are not sure about it, use a grey card that match the reflectance of the
    meter calibration. I say good exposure because there is no perfect exposure
    unless you are experience enough to fine tune one. That is why professionals
    prefer the incident light meter for exposure reading but use it properly and
    correctly or my advice is to use reflected light meter.

    "My View" <no spam > wrote in message
    news:YujXf.20985$...
    > Any suggestions on how to make an accurate grey card?
    > regards
    > PeterH
    >
     
    kctan, Apr 1, 2006
    #6
  7. My View

    Bob Williams Guest

    My View wrote:
    > Any suggestions on how to make an accurate grey card?
    > regards
    > PeterH
    >
    >

    If you have Photoshop or some other graphics editor,create a page in
    Grayscale mode and set the RG&B values at 128, 128, 128. Have the
    printer print it as a B/W image ( to avoid any color bias from printing
    in RGB.) Take that page to a paint store and have them mix up a quart of
    flat or satin paint to match that exact color.
    Cut up some masonite into 3x5 rectangles and paint them gray.
    Give them as presents to your photo buddies. They will appreciate it for
    years to come. If you REALLy want to impress them, paint one side gray
    and the other side pure white.
    I did that and was amazed how appreciative everyone was.
    The 3x5 card fits snugly in a shirt pocket so it is always handy.
    BTW, The 18% gray card only means that its REFLECTIVITY is 18%.
    It generally doet necessarily mean that it has NO color bias.
    I have compared commercial gray cards from different manufacturers and
    they were not the same hue, but they both gave the same (correct)
    reading on the camera's light meter.
    Bob Williams
     
    Bob Williams, Apr 1, 2006
    #7
  8. My View

    Siggy Guest

    In news:LPkXf.1661$kT4.643@fed1read02,
    Bob Williams <> scribed:
    <snip>

    > BTW, The 18% gray card only means that its REFLECTIVITY is 18%.
    > It generally doet necessarily mean that it has NO color bias.
    > I have compared commercial gray cards from different manufacturers and
    > they were not the same hue, but they both gave the same (correct)
    > reading on the camera's light meter.
    > Bob Williams


    God help you if you try and colour balance with it, though. ;-)

    --
    I have no evidence for stating the above, but this is usenet, so I don't
    need any.
     
    Siggy, Apr 1, 2006
    #8
  9. My View

    Mark² Guest

    Bob Williams wrote:
    > My View wrote:
    >> Any suggestions on how to make an accurate grey card?
    >> regards
    >> PeterH
    >>
    >>

    > If you have Photoshop or some other graphics editor,create a page in
    > Grayscale mode and set the RG&B values at 128, 128, 128. Have the
    > printer print it as a B/W image ( to avoid any color bias from
    > printing in RGB.) Take that page to a paint store and have them mix
    > up a quart of flat or satin paint to match that exact color.
    > Cut up some masonite into 3x5 rectangles and paint them gray.
    > Give them as presents to your photo buddies. They will appreciate it
    > for years to come. If you REALLy want to impress them, paint one side
    > gray and the other side pure white.
    > I did that and was amazed how appreciative everyone was.
    > The 3x5 card fits snugly in a shirt pocket so it is always handy.
    > BTW, The 18% gray card only means that its REFLECTIVITY is 18%.
    > It generally doet necessarily mean that it has NO color bias.
    > I have compared commercial gray cards from different manufacturers and
    > they were not the same hue, but they both gave the same (correct)
    > reading on the camera's light meter.
    > Bob Williams


    All well and good...but also a might fine argument for paying your $17.95 @
    B&H for three pre-made Kodak cards!! :) -What a hassle!
     
    Mark², Apr 1, 2006
    #9
  10. My View

    Bob Williams Guest

    Mark² wrote:
    > Bob Williams wrote:
    >
    >>My View wrote:
    >>
    >>>Any suggestions on how to make an accurate grey card?
    >>>regards
    >>>PeterH
    >>>
    >>>

    >>
    >>If you have Photoshop or some other graphics editor,create a page in
    >>Grayscale mode and set the RG&B values at 128, 128, 128. Have the
    >>printer print it as a B/W image ( to avoid any color bias from
    >>printing in RGB.) Take that page to a paint store and have them mix
    >>up a quart of flat or satin paint to match that exact color.
    >>Cut up some masonite into 3x5 rectangles and paint them gray.
    >>Give them as presents to your photo buddies. They will appreciate it
    >>for years to come. If you REALLy want to impress them, paint one side
    >>gray and the other side pure white.
    >>I did that and was amazed how appreciative everyone was.
    >>The 3x5 card fits snugly in a shirt pocket so it is always handy.
    >>BTW, The 18% gray card only means that its REFLECTIVITY is 18%.
    >>It generally doet necessarily mean that it has NO color bias.
    >>I have compared commercial gray cards from different manufacturers and
    >>they were not the same hue, but they both gave the same (correct)
    >>reading on the camera's light meter.
    >>Bob Williams

    >
    >
    > All well and good...but also a might fine argument for paying your $17.95 @
    > B&H for three pre-made Kodak cards!! :) -What a hassle!


    It's a hassle if you don't like to experiment.
    But it is FUN if you like to try new ways to custom make stuff.
    BTW if you get dirt or grease on a Kodak gray card ( which is paper
    based), you cannot easily clean it without seriously altering the
    reflectivity and hue. That is probably why they come in sets of three.
    Bob
     
    Bob Williams, Apr 1, 2006
    #10
  11. My View

    Mark² Guest

    Bob Williams wrote:
    > Mark² wrote:
    >> Bob Williams wrote:
    >>
    >>> My View wrote:
    >>>
    >>>> Any suggestions on how to make an accurate grey card?
    >>>> regards
    >>>> PeterH
    >>>>
    >>>>
    >>>
    >>> If you have Photoshop or some other graphics editor,create a page in
    >>> Grayscale mode and set the RG&B values at 128, 128, 128. Have the
    >>> printer print it as a B/W image ( to avoid any color bias from
    >>> printing in RGB.) Take that page to a paint store and have them mix
    >>> up a quart of flat or satin paint to match that exact color.
    >>> Cut up some masonite into 3x5 rectangles and paint them gray.
    >>> Give them as presents to your photo buddies. They will appreciate it
    >>> for years to come. If you REALLy want to impress them, paint one
    >>> side gray and the other side pure white.
    >>> I did that and was amazed how appreciative everyone was.
    >>> The 3x5 card fits snugly in a shirt pocket so it is always handy.
    >>> BTW, The 18% gray card only means that its REFLECTIVITY is 18%.
    >>> It generally doet necessarily mean that it has NO color bias.
    >>> I have compared commercial gray cards from different manufacturers
    >>> and they were not the same hue, but they both gave the same
    >>> (correct) reading on the camera's light meter.
    >>> Bob Williams

    >>
    >>
    >> All well and good...but also a might fine argument for paying your
    >> $17.95 @ B&H for three pre-made Kodak cards!! :) -What a hassle!

    >
    > It's a hassle if you don't like to experiment.
    > But it is FUN if you like to try new ways to custom make stuff.


    I do like to experiment, and I understand you... I just have a hard time
    getting motivated to build something from scratch that is readily available
    for cheap...unless there's something significantly better to be had by the
    effort and expense.

    I'm sure there are other types of experiments I am willing to do that others
    would find useless or uninteresting...so it's OK.
    :)
     
    Mark², Apr 1, 2006
    #11
  12. My View

    Thomas Guest

    My View wrote:
    > Any suggestions on how to make an accurate grey card?


    Use a white piece of paper and measure two stops down. Always worked
    for me.

    But if you have a DSLR, using the histogram to check your exposure is
    always more accurate then metering a grey card. I think the main use
    of a grey card is to get the color balance right, and then you can just
    as well use a neutral white.

    Thomas
     
    Thomas, Apr 1, 2006
    #12
  13. Bob Williams wrote:

    > It's a hassle if you don't like to experiment.
    > But it is FUN if you like to try new ways to custom make stuff.
    > BTW if you get dirt or grease on a Kodak gray card ( which is paper
    > based), you cannot easily clean it without seriously altering the
    > reflectivity and hue. That is probably why they come in sets of three.


    It's easier and more convenient to carry an Expodisc clone, a piece of white
    translucent (pebble finish) fluorescent light diffuser for perfect WB every
    time.







    Rita
     
    Rita Ä Berkowitz, Apr 1, 2006
    #13
  14. My View

    Tony Polson Guest

    "kctan" <> wrote:

    >There is no such thing as accurate grey card and you don't need a grey card
    >when you measure the incident light for exposure. Grey card is for reflected
    >light exposure measurement like the one in your 300D.



    That is complete nonsense.

    A grey card allows you to make a reading of the incident light falling
    on a scene using a reflected light meter such as the one in an SLR
    camera.
     
    Tony Polson, Apr 1, 2006
    #14
  15. My View

    Tony Polson Guest

    "Thomas" <> wrote:

    >My View wrote:
    >> Any suggestions on how to make an accurate grey card?

    >
    >Use a white piece of paper and measure two stops down. Always worked
    >for me.



    It will only work if you always use a piece of white paper that has a
    reflectance of 72%.

    Try holding a piece of paper steady with one hand on a windy day, and
    you will see why the grey *card* is such a good idea.

    ;-)
     
    Tony Polson, Apr 1, 2006
    #15
  16. My View

    Alan Browne Guest

    My View wrote:

    > Any suggestions on how to make an accurate grey card?
    > regards
    > PeterH



    I believe it is 50% black and 50% white.

    Just buy a studio roll of seamless grey paper (backdrop) cut out a
    section and paste it to a board. Any size you want and you get a nice
    backdrop roll too which, as it's used up, can be converted to grey cards
    for friends, family, profit and fun.

    Cheers,
    Alan


    --
    -- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
    -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
    -- [SI] gallery & rulz: http://www.pbase.com/shootin
    -- e-meil: Remove FreeLunch.
     
    Alan Browne, Apr 1, 2006
    #16
  17. My View

    Don Stauffer Guest

    My View wrote:
    > Any suggestions on how to make an accurate grey card?
    > regards
    > PeterH
    >
    >


    There used to be a brand of mount board that had a medium grey that was
    very close to 18%. We'd buy a lot of that board, 'cause it was great
    for medium tone pictures. We'd cut pieces of that to use as secondary
    grey scale cards.
     
    Don Stauffer, Apr 1, 2006
    #17
  18. My View

    Siggy Guest

    In news:,
    Thomas <> scribed:
    <snip>

    >I think the main use
    > of a grey card is to get the color balance right, and then you can just
    > as well use a neutral white.


    Epson heavyweight matte inkjet paper is good for this. (on a calm day, that
    is :) ) No artificial brighteners in it, apparantly.

    --
    I have no evidence for stating the above, but this is usenet, so I don't
    need any.
     
    Siggy, Apr 1, 2006
    #18
  19. My View

    Clyde Guest

    My View wrote:
    > Any suggestions on how to make an accurate grey card?
    > regards
    > PeterH
    >
    >


    How about picking up a free one? Go to your local Sears or Sears
    Hardware store. In the paint department pick up the paint chip called
    "Pewter". Its number is KK331.

    That chip measures LAB:

    L = 68.28
    a = -0.20
    b = 0.06

    That is VERY neutral in hue. The L means that it is a bit lighter than
    "middle" gray. I use Curvemeister to quickly and easily pin this neutral
    gray chip in Photoshop. It is a very fast way to do color correction.

    I often hold this small chip in the picture and crop it out after color
    correction. Sometimes I take a picture of the chip in the light of the
    picture in a separate shot. In Photoshop I pin the gray and save the
    curve. Then I load that curve in the rest of the shots from that scene.
    It makes color correction quick and easy.

    The beauty of this neutral gray is that it is FREE! Just go pick one up.
    Hey, pick up a bunch of them. Now you don't care if it gets wet,
    damaged, or lost - there are a bunch more available for the same price.

    --------------------------

    I have found another neutral gray that gives a lot of flexibility.
    Golden Neutral Gray N5 acrylic paint.

    http://www.goldenpaints.com/products/color/heavybody/colors/1445infopg.php

    I went to my local art supply store and bought a 2 oz. tube of this
    paint. (Not all carry Golden, but there are plenty of Web places to buy
    it too.) Now I can paint anything I want to be my gray card. Actually
    the one I use the most is the lid of a metal AOL case that I painted the
    inside of the cover with this paint.

    Golden nicely tells us what the LAB color is:

    L = 52.02
    a = -0.21
    b = -0.28

    That is about as neutral of a gray that you will find. It makes
    excellent gray cards. Of course, I have a pin for this in Curvemeister.
    You could do color correction with this gray and without Curvemeister.

    Keep in mind that LAB 50% L is NOT the same as 18% reflectance. It isn't
    even the same as RGB 128,128,128. I'm not going to go into the science
    of color in CIELAB. Read the book "Photoshop LAB Color" for all that.
    Actually, Golden N3 or N4 may be closer to an 18% reflectance card.
    You'll have to experiment with that; I don't care.

    Nevertheless, you should be able to get neutral colors with either of
    these grays in your picture. You may have to adjust the overall
    brightness (L), but it should be consistent. Well, with one caveat...

    Watch out how you hold these in your shot. These, or any other, can
    reflect some glare that will affect your correction. They are both a
    semi-matte and not a full matte. I find that 45 degrees from the source
    of the light works pretty well.

    Have fun.

    Thanks,
    Clyde
     
    Clyde, Apr 1, 2006
    #19
  20. My View

    Clyde Guest

    Bob Williams wrote:
    >
    >
    > My View wrote:
    >> Any suggestions on how to make an accurate grey card?
    >> regards
    >> PeterH
    >>

    > If you have Photoshop or some other graphics editor,create a page in
    > Grayscale mode and set the RG&B values at 128, 128, 128. Have the
    > printer print it as a B/W image ( to avoid any color bias from printing
    > in RGB.) Take that page to a paint store and have them mix up a quart of
    > flat or satin paint to match that exact color.
    > Cut up some masonite into 3x5 rectangles and paint them gray.
    > Give them as presents to your photo buddies. They will appreciate it for
    > years to come. If you REALLy want to impress them, paint one side gray
    > and the other side pure white.
    > I did that and was amazed how appreciative everyone was.
    > The 3x5 card fits snugly in a shirt pocket so it is always handy.
    > BTW, The 18% gray card only means that its REFLECTIVITY is 18%.
    > It generally doet necessarily mean that it has NO color bias.
    > I have compared commercial gray cards from different manufacturers and
    > they were not the same hue, but they both gave the same (correct)
    > reading on the camera's light meter.
    > Bob Williams
    >


    That assumes that your printer profiles are perfectly color corrected to
    the paper you are using. That is a highly suspect assumption for most
    people.

    In another replay I suggested that you go pick up the Sears paint chip
    "Pewter" - KK331. This really is a neutral gray. Of course, you could
    get paint made in that color too, but if you have the chip you don't
    really need the paint.

    Clyde
     
    Clyde, Apr 1, 2006
    #20
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