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Thread: Poor man's ExpoDisc - Coffee Filters!

  1. #21
    Moderator Clown's Avatar
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    good article.. i'm also an advocate for coffee filter WB. always have a pack with me when i go shooting.
    sommore it can act as flash diffuser, rough paper, sketching paper, toilet paper... etc.
    sigh.

  2. #22

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    Quote Originally Posted by Denosha
    I've just updated the article. Hopefully it's now more informative and accurate.
    The Custom White Balance done with the coffee filter has a cyan colour cast.

  3. #23
    Senior Member denniskee's Avatar
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    May I know the diff between using a white surface after putting on the coffee filter & not having the white surface?

    If there is a diff, then why not shot directly onto the white surface? Why cover the lens with the coffee filter?

    Does the "expodisc" needs the white surface for setting CWB?

    Many thanks.
    photography makes one sees things from all angles.

  4. #24

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    From what i understand, setting white balance requires the exposure from a "medium grey" exposure (127-127-127 RGB). Which is why people also use grey cards to set white balance. What the coffee filter does is to simulate this "greyness" while allowing the ambient light conditions to filter through. I haven't tried using an exposure of just a white surface to set as the custom WB but i doubt it works that well. Just my $0.05 on how i think it works. I could be wrong.

    Anyway, about the cyan cast. Yeah, i noticed that too but as i've said in the article, it's only "near perfect" and "your mileage might vary". If you look at the comparison between the various WB modes, it's as close to ideal as it gets. Of course if you shoot raw, u can get it even more accurate in post processing. But like i've said, this is a quick+cheap fix so don't expect it to be the magic bullet

  5. #25
    Moderator catchlights's Avatar
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    Quote Originally Posted by Denosha
    From what i understand, setting white balance requires the exposure from a "medium grey" exposure (127-127-127 RGB). Which is why people also use grey cards to set white balance. What the coffee filter does is to simulate this "greyness" while allowing the ambient light conditions to filter through. I haven't tried using an exposure of just a white surface to set as the custom WB but i doubt it works that well. Just my $0.05 on how i think it works. I could be wrong.

    Anyway, about the cyan cast. Yeah, i noticed that too but as i've said in the article, it's only "near perfect" and "your mileage might vary". If you look at the comparison between the various WB modes, it's as close to ideal as it gets. Of course if you shoot raw, u can get it even more accurate in post processing. But like i've said, this is a quick+cheap fix so don't expect it to be the magic bullet
    A pc of white card will work as like an 18% grey card, but not all white is pure white, I mean no colorcast in it. (some cyan added in it to make white whiter)

    Is very easy to remove the (same) color cast in PS using batch processing with action, if let say you have few hundred images to work on.

    if you want very perfect custom WB, use ExpoDisc, or at least 18% gray card.

  6. #26
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    wow! i am very impressed by the results! incredible, to say the least.

    must try out... even though me using a prosumer digicam only.

  7. #27

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    Quote Originally Posted by denniskee
    May I know the diff between using a white surface after putting on the coffee filter & not having the white surface?

    If there is a diff, then why not shot directly onto the white surface? Why cover the lens with the coffee filter?

    Does the "expodisc" needs the white surface for setting CWB?

    Many thanks.
    Paper not necessary. Point expodisc at light source & white balance.

  8. #28
    Senior Member denniskee's Avatar
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    Quote Originally Posted by MoriMori
    Paper not necessary. Point expodisc at light source & white balance.
    Is there a different between doning CWB by point the disc @ light source (assuming only 1 artificial light source) as to pointing the disc to white surface?
    photography makes one sees things from all angles.

  9. #29

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    By 1 source you mean theres only 1 temperature and 1 color right? If thats the case it shouldn't be any different.

    Expodisc list 2 situations, either you can wb the source, or wb the scene, averaging out what they call the 'ambient soup' if its more than 1 type of light.

    http://www.expodisc.com/products/exp...tructions.html

    I don't own an expodisc so may or may not be right.

  10. #30

    Default Re: Poor man's ExpoDisc - Coffee Filters!

    Ooops.. I didn't realise the link was down after my webhost moved me. Anyway, it's back up again at the original URL (http://www.sgl.per.sg/~denosha/CoffeeFilterWB/) in case anyone is still interested in it after 2 years. Hur hur.

    The coffee filters have since turned yellow though. =^/

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