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Thread: Grey Cards

  1. #1
    JK6065's Avatar
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    Grey Cards

    I just came across a article about gray cards. The article made perfect sense but I was wondering how it works in reality. So therfore my question: are you using a graycard for setting the whitebalance? If yes, under what circumstances do you recon a graycard as a useful help or even a must? Are these graycards a common thing in photographer's stores or should a order one on the internet? And do you have any tips on how to use them.

    Thanks in advance.

    Regards,

    Jeroen

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    Moderator Dave Humphries's Avatar
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    Re: Grey Cards

    Hi Jeroen,

    I don't personally use one at the moment.
    Having said that, I am intending to get one soon (birthday coming up ).

    My intention is to go for a Whi-bal card, as more durable and lighter than the 18% grey cards.

    Also having said that, as the penultimate paragrpah of that article states, if you shoot RAW, it is far less of an issue, since you can adjust it in PP without untoward side effects.

    However, there are times when (particularly if inexperienced like me), it can be difficult to know what colour temperature to set it to in PP if there's nothing black, grey or white in the shot. This is when a reference shot of the Whi-bal or Gray card, taken under the subject's lighting conditions, can be useful.

    However, they must be used with caution; you don't always want the colour temperature "neutralised" - a sunset won't look pretty without its red glow, to give but one example!
    Furthermore, it may not be possible to get the Whi-bal or Gray card into the subject's lighting, think of a floodlit sports or events stadium; the audience/spectator isn't under the same lights as the stage/pitch/field/track, and there are usually fences, burly blokes and even dogs to stop you getting there!

    So, it may be of limited use if you happen specialise in taking shots where it won't help or cannot be used effectively.

    Hope that helps,

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    Re: Grey Cards

    Quote Originally Posted by JK6065 View Post
    Therfore my question: are you using a graycard for setting the whitebalance?
    Yes.

    If yes, under what circumstances do you recon a graycard as a useful help or even a must?
    Any time you need accurate colours - most often when photographing people where skin tones are of primary concern.

    Are these graycards a common thing in photographer's stores or should a order one on the internet?
    I use a WhiBal card - which you should be able to get via the net without too much trouble.

    And do you have any tips on how to use them.
    Easy. Just include the card with a test shot (eg get your subject to hold it). In post-processing (if your using Photoshop anway) you simply need to click on the gray card with the whitebalance tool to instantly adjust the whitebalance (assuming Adobe RAW converter) (CS3, CS4, which handle both RAW and JPEG image formats). Once you know the correct temperature and tint you can then apply these to all other images shot under the same lighting.

    Technically what it's doing it calculating the colour cast on the card and automatically adjusting the image so that it's nulled out.

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    Re: Grey Cards

    I use a plastic white card that I had at home. Should I buy a special card?

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    Re: Grey Cards

    I think I'll go for the Whibal. Thanks for your advise.

    Greentea:
    over here is a page with a lot of explanations about the Whibal. It also shows why a Whibal is better than others and especcially where the difference is (especcially number 4 I found interesting). Don't know if it's that good as they say it is but do with it what you want to.

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    Re: Grey Cards

    Thank you, JK I've watched the videos and read your article now, so I understand that a grey (neutral) card is better. I'm definitely curious to try one!

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    Re: Grey Cards

    Quote Originally Posted by GreenTea View Post
    I use a plastic white card that I had at home. Should I buy a special card?
    The bottom line is "if your happy with the results your getting from whatever your using now", then I wouldn't get too excited about spending more money. Apparantly coffee filters work quite well as well.

    Trick is to make sure it's not close to blowing the channel when you photograph it - if any of the 3 channels are blown then the area can't be used for whitebalancing.

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    Re: Grey Cards

    Colin thanks for the info on the WhiBal card, it's just what I've been looking for. Love the idea of using the black patch to avoid glare.
    My pocket hates you, I just ordered one.

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    Re: Grey Cards

    Quote Originally Posted by Bill44 View Post
    Colin thanks for the info on the WhiBal card, it's just what I've been looking for. Love the idea of using the black patch to avoid glare.
    My pocket hates you, I just ordered one.
    Hi Bill,

    I'd love to take the credit, but I think you might be referring to the link that JK6065 provided?

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    Re: Grey Cards

    Oooooops!

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    Re: Grey Cards

    I'm excited with the results I'm getting with the improvised card because it's a huge improvement from the horrible camera's automatic setting choices (they're like red-redder-reddest, hehe). But I'm curious about a grey card now. Two questions:

    1. Will I get an idea of the difference by using a light grey improvised card?
    2. What does "blowing the channel" mean? I wasn't able to find it in Google...

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    Re: Grey Cards

    Quote Originally Posted by GreenTea View Post
    1. Will I get an idea of the difference by using a light grey improvised card?
    No way of knowing. It's not the "degree" of grey that makes the difference, it's the fact that it doesn't alter the balance of reflected light in any of the three channels. And if it happens to exhibit this characteristic across the entire range of temperatures that your shooting under, then so much the better (reduced metamerism).

    2. What does "blowing the channel" mean? I wasn't able to find it in Google...
    It's when there's too much light hitting the sensor for it to record, so it "maxes out". We normally think of this in terms of all channels (ie red, green, and blue), but when theres a strong bias towards one channel (eg red flower or a sunset), one channel will max out waaaay before the other two - then you don't have anything to white balance from. This is why you get distinctive coloured banding around bright/temperature-shifted scenes (eg sunsets), and why it's difficult to photograph bright red flowers (you have to under-expose them).

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    Re: Grey Cards

    Quote Originally Posted by Dave Humphries View Post
    My intention is to go for a Whi-bal card, as more durable and lighter than the 18% grey cards.
    On a side note Dave, it's an 18% gray card too

  14. #14
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    Re: Grey Cards

    Colin, does the risk of blowing one of the channels before the others get solved by using a 18% grey card?

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    Re: Grey Cards

    Quote Originally Posted by GreenTea View Post
    Colin, does the risk of blowing one of the channels before the others get solved by using a 18% grey card?
    Compared to a white card, yes; the less reflectance the less light that gets reflected and the less change of over-exposing that area.

    Doesn't mean to say it'll do anything to save the rest of the shot though.

    Basically, if you use a white card then you can also guarantee that it'll be the brightest thing in the scene, thus most likely to blow.

  16. #16
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    Re: Grey Cards

    I used a piece of gray paper now, and the difference in colors is very noticeable, so I decided to buy a grey card. The only kind they have here is Kodak. Is that good enough or should I continue shopping?

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    Re: Grey Cards

    Quote Originally Posted by GreenTea View Post
    I used a piece of gray paper now, and the difference in colors is very noticeable, so I decided to buy a grey card. The only kind they have here is Kodak. Is that good enough or should I continue shopping?
    Ultimately, who knows. Kodak gray cards were originally designed for exposure, not white balancing (thus didn't need to be spectrally neutral), but I've no idea what the latest ones are like.

    If nothing else, the WhiBal cards are probably a lot more robust (and you can clean them when they get dirty) - I suspect you won't get a big colour shift though.

  18. #18
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    Re: Grey Cards

    In the turotialvideo it is being said that other gray cards aren't totally gray. In them there are some colours instead of the complete gray (one line in the histrogram) of the Whibal. That's what should be the difference but I can't really tell you whether this is true or just a way of advertising and cheering up their own product. If it's actually true what they point out, I doubt if you even can tell the difference among the results with the cards in a photo. Maybe if you hold two photo's of the exact same scene with different gray cards next to eatch other, but I don't know if that differnce really bothers you...
    Last edited by JK6065; 29th June 2009 at 07:51 PM.

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    Re: Grey Cards

    18% gray card

    I use a Nikon D80 and in most circumstances it overexposes when using a card. I find a colour check card more useful. But having said that I shoot in RAW. And then I fiddle. And then I can't stop. And I fiddle some more and then it's three in the morning.

    Damn you, Photoshop & Capture NX!

  20. #20
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    Re: Grey Cards

    Quote Originally Posted by Chelseablue View Post
    And then I fiddle. And then I can't stop. And I fiddle some more and then it's three in the morning.
    LOL I thought that was just me

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