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Thread: How to use a grey card.

  1. #1

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    How to use a grey card.

    I recently bought a grey card for balancing color. I don't really know how to meter though. I have a Canon EOS Rebel XS because I just begun photography in December. If they is a tutorial can you give me the link or else can someone teach me how to use it.

    Thanks!

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    re: How to use a grey card.

    Unless you're shooting in a studio then I wouldn't bother using the grey card for metering. Rely on the cameras (very good) meter and tweak the results once you've seen the histogram on the LCD.

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    re: How to use a grey card.

    Hi "Canonman13",

    Please, do tell us a first name - and pop it into the Real Name slot when you Edit your Profile - thanks.

    You start by saying "I recently bought a grey card for balancing color" but then talk of "meter"ing (i.e. exposure), so we may be a cross purposes.

    Tutorial links;
    Camera metering and Digital exposure techniques
    White balance

    The latter has a bit on setting a Custom White Balance, which is possibly what you meant.

    Cheers,

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    re: How to use a grey card.

    If you have bought a grey card use it. Not just in the studio but where ever it is practical. Take your meter readings from it as a good way of getting good exposure computations. Like many here I started in the era of film, before all but the most expensive cameras had in-built meters and metering using a handheld meter ( e.g. Weston Light Master IV or V) and a grey card was common practice. At the very least it will make you think about what an all singing and dancing digital camera meter is doing in computing exposure and, by that means, you will get to know when the camera is telling you sense or nonsense. The point is any exposure meter (in-camera or out) is trying to give a reading according to what would be an average grey like your 18% grey card, so its 'best' reading in the prevailing light will be from such a grey card. I just used to find it indespensible for giving me a reference point of exposure calculation and then from there judging the highlights and shadows of any particular scene ( i.e stops over and under) to decide finally what exposure I was going to give the pic I took in the pre-digital film era. Does that help? Perhaps the biggest thing for you to do is try some shots using the card and the readings it gives against the same shots not using the card, just metering the scene as is - then you will hopefully have the answer as to why I think it is not a bad thing to use a grey card where posible.

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    re: How to use a grey card.

    You will find out what your camera meter does if you take 3 photos, one of a white card, one of a black card and one of a grey card. Set your camera to Auto, fill your viewfinder with the card and don't worry about focus. See what you get - they will all three turn out mid grey! So you will have to increase the exposure of the white card by around 2 stops to force the camera to make the image white, and reduce the exposure of the black card by somewhere round the same amount to force the camera to make the image glack. This is because the meters work on the basis that an average image works out at mid grey

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    re: How to use a grey card.

    If you want to white/color balance with a gray card, there are two methods for doing so. In-camera, you fill the frame with the gray card, take a picture, and then set your custom white balance to use the image you took of the gray card. Or. You set the camera to shoot in RAW, and when you take a shot that you know you'll want to color balance in post, you take a second shot of the same scene but with the gray card in it, to serve as a reference point. Then, you can use that as the source area for an "eyedropper" correction.

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    re: How to use a grey card.

    Quote Originally Posted by inkista View Post
    You set the camera to shoot in RAW, and when you take a shot that you know you'll want to color balance in post, you take a second shot of the same scene but with the gray card in it, to serve as a reference point. Then, you can use that as the source area for an "eyedropper" correction.
    Also works for JPEGs in later versions of ACR.

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    Re: How to use a grey card.

    Quote Originally Posted by Colin Southern View Post
    Also works for JPEGs in later versions of ACR.
    I always assumed it worked with JPEGs. But if you're shifting color temp too far with a JPEG, you can get those weird artifacts from JPEG compression having dumped/consolidated some color values. RAW is still going to give you more latitude.

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    Re: How to use a grey card.

    Quote Originally Posted by inkista View Post
    I always assumed it worked with JPEGs. But if you're shifting color temp too far with a JPEG, you can get those weird artifacts from JPEG compression having dumped/consolidated some color values. RAW is still going to give you more latitude.
    For sure - and absolutely agree that RAW is better; I just thought it read that with what you were suggesting, it only applied to a RAW capture when in reality you can white balance a jpeg just fine the same way (assuming there isn't a large correction required).

  10. #10

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    Re: How to use a grey card.

    Thanks for all your guy's help!

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    Re: How to use a grey card.

    This thread, and the one on the colour checker passport recently has been very useful. The passport thread got me thinking and I decided against it in favour of the WhiBal for several reasons. It was 15 as against 76, so if it turned out not to be all I wanted it wouldn't be a great loss, very small, (credit card size), garunteed accuracy ( not absolutely essential but no harm to have) is virtually indestructable and should last a life time. Above all, it is very easy to use as Michael Tapes videos makes clear, and as easy to use to correct shots in ACR afterwards. It seems to me that the colour checker passport is a great idea that goes beyond the grey card but, (for amateurs like me) costs significantly more and, I read, should be replaced every 2 years or so. It is also bigger and has to be opened up and so is likely not quite so simple to use it tricky situations. In time, perhaps, there will be a credit card sized passport as robust and accurate as the WhiBal but I guess the cost will be a lot more. I would love to run my own comparison between the WhiBal and the Passport and I wonder if anyone in CiC has done so.

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    Re: How to use a grey card.

    Quote Originally Posted by ANSORB View Post
    This thread, and the one on the colour checker passport recently has been very useful. The passport thread got me thinking and I decided against it in favour of the WhiBal for several reasons. It was 15 as against 76, so if it turned out not to be all I wanted it wouldn't be a great loss, very small, (credit card size), garunteed accuracy ( not absolutely essential but no harm to have) is virtually indestructable and should last a life time. Above all, it is very easy to use as Michael Tapes videos makes clear, and as easy to use to correct shots in ACR afterwards. It seems to me that the colour checker passport is a great idea that goes beyond the grey card but, (for amateurs like me) costs significantly more and, I read, should be replaced every 2 years or so. It is also bigger and has to be opened up and so is likely not quite so simple to use it tricky situations. In time, perhaps, there will be a credit card sized passport as robust and accurate as the WhiBal but I guess the cost will be a lot more. I would love to run my own comparison between the WhiBal and the Passport and I wonder if anyone in CiC has done so.
    Hi John,

    I have both, but they're different tools for different jobs.

    - A gray card is used for white balancing

    - The colour card is used to create a custom camera profile

    The first allows a correction to be applied that compensates for the colour temperature of the lighting, the second allows a correction to be applied that compensates for the difference between the camera profile used by your RAW converter -v- the actual colour performance of your camera.

    The colour checker passport also has a greay card by the way, as the shots still need to be white balanced even with a custom profile.

    In practice, the passport makes a small but significant difference - when shooting portraits especially, anything that increases the accuracy of skintones is a VERY good thing.

  13. #13

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    Re: How to use a grey card.

    Quote Originally Posted by Colin Southern View Post
    Hi John,

    I have both, but they're different tools for different jobs.

    - A gray card is used for white balancing

    - The colour card is used to create a custom camera profile

    The first allows a correction to be applied that compensates for the colour temperature of the lighting, the second allows a correction to be applied that compensates for the difference between the camera profile used by your RAW converter -v- the actual colour performance of your camera.

    The colour checker passport also has a greay card by the way, as the shots still need to be white balanced even with a custom profile.

    In practice, the passport makes a small but significant difference - when shooting portraits especially, anything that increases the accuracy of skintones is a VERY good thing.
    Colin

    That is a good summary of the difference and I'll stick with the WhiBal for now. I don't do portraits but even with family shots skin tones can be very difficult and get the most critical comment. The family is pretty tolerant but I know they and everyone else like it a lot better when skin tones are spot on so I can see a case for the passport there. In most other areas I'm not so sure, how often would the the passport make significant improvement in landscape, sports, street, and architecture shots, for example, over and above simple white balancing? And if you do use it in those situations is it more or less as easy to use as the WhiBal? (I mean in terms of physical handling) That was the burden of my question about a comparison between them.

    One can do a certain amount of colour correction in Photoshop but only in so far as one can avoid colours which are definitely wrong. (I don't see how you restore accurate colours - i.e. to what their RGB or LA*B* values would have been - when you don't know what they were in the first place, so anything more than avoiding the impossible is a matter of taste and visual memory). For most things that seems to be fine, but I do wonder if the passport could sometimes get you just that bit closer to "reality" and act as a visual memory jog, and, perhaps, reduce reliance on taste and memory in post processing. My guess is: not often and not significantly. What do you think? (I am not thinking of controlled situations like studio portraits and product shots).

    I hope I haven't confused myself again. I'm sorry this is a bit long.

  14. #14

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    Re: How to use a grey card.

    Call me old fashioned, but I was using a grey card 40 years ago when digital cameras and white balancing were not even a glint in anyone's eye. The film was balanced for a certain temperature and that was that. You could muck it about by using filters or even create interesting effects by using, say, Tungsten balanced film in daylight, but using your grey card was not used to do anything about the balance of the film. It was used for claculating exposures and overcoming the bias of light meters to measure 'grey'. It has only been with the advent of digital cameras that the application of the grey card has become more than just an exposure aid. Colour cards were also around years and years ago and the really diligent enthusiast would shoot a colour card for each film type he used so as to assess it and hence determine which films were better for which type of application depending upon their individual colour balance. So it just all re-inventing the wheel as far as I am concerned.

  15. #15

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    Re: How to use a grey card.

    I think I am just going to get a expo disc.

  16. #16

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    Re: How to use a grey card.

    Quote Originally Posted by Canonman13 View Post
    I think I am just going to get a expo disc.
    Hi Tyler,

    I have two, and I don't use either - frankly, in any situation involving flash or mixed lighting, they're useless.

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