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Thread: White Balance Issues

  1. #1

    Default White Balance Issues

    Like to know what's the meaning when one says meter your WB against an 18% grey card when you want to do Manual WB?

    Not sure abt this technical issue. My D50 gives ickish WB under incandescent lighting, so someone just told me to meter 18% card w/o explaining to me what it actually meant!

    Sidetrack, what's the meaning of bokeh?

  2. #2

    Default Re: White Balance Issues

    i have a D50 and have the same problems. setting the white balance tells the camera what is white so that the camera can then render all the colours accurately. so when you do a manual WB you need to shoot something which has absolutely no colour in it. in practice, you can use any pure white card to set the white balance as well. if you need perfection, you have to buy one of these cards which are caliberated to have no colour tones. (white paper usually has some yellow or blue tint). i personally use a white paper and the results are always fine.

    bokeh is the rendering of objects which are out of focus in your image. different lenses render this differently. many people prefer the oof background to be smooth and creamy. some lenses render a harsh oof with lots of edges. among other things, it also has to do with the aperture blades of the lens. aperture blades which form a circular opening are better than the ones that form a polygonal opening.

    regarding the 18% grey. i have a few questions as well. i hope someone can answer
    exposure meters are caliberated to 18% (disputed by some who say it is 12%) grey, which means that if i shoot a perfectly white card at a setting where the camera says it is perfectly exposed, the resulting image would be 18% grey! that is why, it is advised to dial positive compensation in bright images and negative compensation in dark images although this sounds counterintuitive. this is because with no compensation, the camera will render the bright image as dark as 18% grey and the dark image as bright as 18% grey.

    now what i am wondering is that if we do a manual WB using 18% grey, does the camera start metering for pure white instead of 18% grey?

  3. #3
    Moderator catchlights's Avatar
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    Sep 2004
    Punggol, Singapore

    Default Re: White Balance Issues

    As long a surface of object is neutral, like white (RGB, 255,255,255) or gray (RGB 128,128,128), you may use as a white balance reference.

    So a gray card (18% gray) can use to measure white balance and exposure reading for digital photography.

    Doing a preset white balance can help you getting a neutral tone on tricky lighting condition.

    For how to do a preset white balance on your camera please refer to you camera manual.

    For the exposure metering part, all camera exposure meter, hand held exposure meter are calibrate to mid tone gray, 18% gray, or call it zone V, when you take Reflected Light exposure meter reading, you suppose to use a mid tone as reference, if you use other then mid tone to take your reading, you need to compensate accordingly.

  4. #4

    Default Re: White Balance Issues


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