 David K |
Digital Photography in Fluorescent Lights I am trying to shoot a bunch of pamphlets and books in a lighting booth that is fluorescent lighting. The booth is all white. I am using a digital Canon A80. I have set a custom white balance (off a piece of typing paper), shooting on manual on a tripod with an ISO setting of 100. When I import the shots into Photoshop on my Mac, I have noticed the white background often appears gray. When I shoot, I am getting a +0 reading. Is there a way to overcome this gray/white issue (aside from not shooting under fluorescents?). I'm kind of stuck with it and making the best of what I have. I have compensated by setting a little overexposure, but I was wondering if this is necessary and if I'm not doing something that should be done. Thanks!
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Rhonda L. Tolar |
I don't know much about digital, but can you set a custom white balance off of the white background? Shouldn't that work?
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Jon Close |
Setting white balance keeps the photos from taking on a color cast from different light sources - daylight v. tungsten v. fluorescent. That the white subject appears gray is due to the exposure meter being fooled. The meter is set to expose as if the light is being reflected from 18-percent gray, which a typical scene would average. If the scene/subject is largely white, the meter thinks the scene is brighter than it actually is and so tends to underexpose. In these situations (white wedding dress, beach sand or snow, etc.) you correct this by applying between +1 and +2 exposure compensation. The opposite occurs if your subject is much darker color - eg., black tuxedo, black Labrador retriever, etc. In this case, the meter will tend to overexpose, rendering the subjects gray instead of black. This is corrected the opposite way, by applying negative exposure compensation.
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David K |
Thanks both for your responses. Jon, your answer explains why I've had to bump up the exposure compensation so much. Sometimes up to +2/3. Thanks for the technical explanation.
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Rhonda L. Tolar |
So, if David had used a gray card to do an exposure reading, the white background would be white?
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Jon Close |
Yes. Set white balance off a white card to prevent whites from taking on blue, yellow, magenta, green ... cast. Meter off a calibrated gray card to keep white (and black) from being rendered gray.
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Rhonda L. Tolar |
Thanks, Jon, for clearing that up for me. I am just now getting started out in digital, and let me tell you ... I am very confused!
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David K |
Jon, when you say meter off the gray card (sorry, I am new at this too), do you mean take the exposure metering off the card?
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Jon Close |
Yes. Place the gray card in the same light as your subject, and meter it. In centerweighted or evaluative/matrix metering, the card should fill at least 75 percent of the viewfinder, or you can spot/partial meter the card.
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Darrell Jensen |
I use a product to set exposure/WB called Expodisc. It does corrects the exp/WB in camera better than I ever did post-process. I have and have used Greycard and Whitecard. ED is much easier, especially for long distance, wide angle shots, but also for product and potrait photography.
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Darrell Jensen |
I use a product to set exposure/WB called Expodisc. It does corrects the exp/WB in camera better than I ever did post-process. I have and have used Greycard and Whitecard. ED is much easier, especially for long distance, wide angle shots, but also for product and potrait photography.
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