Tammy L. Murdock
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How to Keep White Backdrops White
I have just painted a wall white in my small home studio. I took some test shots and they turned out bad... the white looks very grey in some and orange in others. (I was trying different white balances.) Any suggestions?
3/4/2006 8:24:21 PM
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Justin G.
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Some are grey because you underexposed. Try opening up a stop or two. And set your WB to daylight, because flashes are balanced for the ~5500K daylight.
3/4/2006 8:58:33 PM
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Ken Raymond
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Just to add to what Justin said, when your camera sees a lot of white in the frame, the metering system automatically tries to bring the image to an 18% gray and, under normal instances, would give you good results. But when you introduce a lot of white you are fooling the metering system and the camera tries to make it gray. You can do what Justin recommends and overexpose by one to two stops, or you can use the exposure compensation feature to overexpose. The other option is to use a light meter.
3/5/2006 5:52:35 AM
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Laura E. OConnor
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You could also set the custom WB off of a graycard so that the camera will read the gray as neutral, therefore it will read the white as white.
3/7/2006 6:10:41 AM
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Christopher A. Vedros
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Tammy,
Justin and Ken are both trying to tell you the same thing, and they are all correct.But HOW you actually follow their suggestions will determine if it works or not. Like they said, the problem is that the white wall reflects more light than most other objects, so the camera's meter will try to make the wall look grey. Using a hand-held light meter will only make a difference if you use an "incident" light meter. This would be held at the wall and aimed back at the camera to measure the light falling on the wall. Aiming a "reflected" light meter at the wall will give the same reading as the meter in your camera. If you are shooting in Aperture Priority mode (Av on Canons), opening up a stop or two won't help because the camera will just increase the shutter speed to match. In this mode, you would need to adjust your Exposure Compensation to +1 or +2. Then, whatever aperture you choose, the camera will pick a shutter speed to give you a 1-stop or 2-stop overexposure for a white wall. Exposure compensation will also fix the shot if you are shooting in Program mode. If you are shooting in Manual, you need to adjust your shutter speed or aperture until the meter reads a +1 or +2 overexposure. If you are shooting in full Auto mode, your white wall is probably going to stay grey. Laura - I've never tried setting custom WB off of a gray card. I don't think that would help the exposure problem. Setting the custom WB off of the white wall would correct for any color in your light source. Chris
3/7/2006 6:48:49 AM
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sandeep mahal
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I think you are only lighting the subject. If you want the background to be white, you will have diect one light towards the wall and the light on wall should be one or two stops more than on the subject. White balance shold be selected according to the lighting. You can also make background of any colour you want by putting a coloured film on the light pointing the wall and then changing its intensity.
3/7/2006 7:29:08 AM
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Laura E. OConnor
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Hi, Chris. The custom WB off the gray card would definitely help. You could use white, but to get perfect balance between white and black, a gray card is the way to go. It reads it as neutral, so the whites become white and blacks become black. I honestly don't know in what cases you'd use a white card or black card over the gray or visa versa, I just know that the gray card has been recommended in every book or article I've read. I'll have to look up info on the white card, though! Definitely more light is in order,but if you are working with natural light, that's not easy to do. If you have studio lighting, then you can play. If you want true high key bright white, you need LOTS of light on the background. Hope that helps! I don't even set my WB in the studio. I have it set to auto and leave it alone. In most cases, auto WB works fine with the D70.
3/7/2006 7:37:57 AM
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Tammy L. Murdock
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Thanks everyone, I did my shoot yesterday and the white turned out ok, using your suggestions. It certainly was not the high key white I was hoping for, but was fine in this case. Sounds like I need to point more light to wall. I was using 2 continous lighting sources (one at wall one at subject). Some shots required a third with a reflector to fill in shadows.
I was shooting in AV mode at f5.0 for most shots...but some are really out of focus, so now I need to play using differnt fstops. (I thought in order to blur background I should be at f5 or so, but maybe not...)
Thanks again.
Tammy
3/7/2006 8:26:10 AM
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Alan N. Marcus
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There are no hard and fast rules in portraiture. However, you goal should be to make pictures that sell so you can eat and pay the rent. I strongly suggest you practice using black-and-white film You control the end-result tonal range (contrast) by lighting ratio. Basic lighting is with two lights. A main and a fill. Background control requires three lights. First concentrate on placing the Main and the fill. You always fill shadows from the camera’s prospective so the fill is placed on a line as close to the lens as is permissible. The main is placed higher and usually off to the side. Exposure is based only on the fill (expose for the shadows). Turn everything off but the fill and take your meter reading Best is incident reading. Second best is reflected reading from gray card. Third is reflected reading off face adjusted less one f stop (flesh is generally reflects one f stop more light than a gray card). Set main one f stop brighter than fill, ratio will be 3:1 result is normal contract image. Set main two f stops brighter than fill, ratio is now 5:1 higher contrast. Next set main three f stops brighter than fill, ratio is 9:1 for theoretical lighting. That all there is, film has a limited contrast range. Setting ratio: If main and fill are equal in brightness, ratio will be 2:1, too flat. Start by measuring main to subject distance, multiply by 1.4, place fill further back to this adjusted distance. This causes the fill to be less intense by 1 f stop. Ratio will be 3:1, good money-making technique. One more time, back up by the 1.4 factor, ratio becomes 5:1 more contract more dramatic. One more time is 9:1 lots of contract very theatrical. Distance changes for brightness adjustments become less accurate for broad sources like umbrella lights. Stated another way, best to measure each lamps effect at the subject with an independent meter reading. The shade of gray the background will obtain is controlled by the intensity of the background light. This third light is placed behind subject and shines backwards to illumining background. For white, adjust intensity via distance from background or by brightness setting. Same 1.4 factors apply. As a general rule white is achieved when background is illuminated about 5 f stops brighter than the fill. Keep in mind, camera exposure is always based on the fill. The rule is “exposed for the shadows”. Adding two more lights, hair and rim (kicker) complements a studio setup. Alan Marcus
3/7/2006 9:20:35 AM
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