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08/27/2005 03:23:29 PM · #1 |
| Ok, ok, this site is making me lazy. It's too much of an effort to seek this out when I know others have been there, so be kind and save me the trouble , please point the way to unsolve the mysteries of white balance. |
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08/27/2005 03:47:54 PM · #2 |
Surely you want to "solve" them or "resolve" them? Not UNsolve them?
1. Have you ever sat inside, under house lights, looked out the window, and seen a VERY nice deep blue/magenta-looking sky at dusk? And you go out to admire it, and in a couple minutes it looks less colorful? Then you go back inside and it's all yellow in there? And a couple minutes later it looks normal? That's white balance, and your brain is "filtering" it to neutral.
2. Light comes in many different colors, or "temperatures". They are measured in "degrees kelvin". Noon daylight is roughly 5800 degrees kelvin, tungsten light roughly 3200 degrees kelvin, etc. The higher the "temperature" the bluer the light, at least within the visible range.
3. The camera doesn't "know" the temperature of the light it is seeing, so it has to make assumptions. You can tell it what assumption to make by setting your white balance to tungsten, daylight, whatever. You can set "auto white balance" where the camera evaluates the scene and makes its best guess as to the color temperature of the light. Most of the time this works fairly well.
4. Note that you probably have "cloudy" and "shade" setting also; these are very useful; the light on an overcast day is significantly more blue than sunlight from a clear sky, and even on a clear, bright day shadow illumination is very blue because it is composed largely of light reflected from the blue sky, so you need to compensate for that. These settings are very helpful when shooting in an overcast or in open shade.
5. The best way to understand how it works is to set the camera up and shoot the same scene with different WB settings. Be sure to make notes which order you did them in. Then view all the images together as thumbnails and the differences will be obvious. Use the same exposure for each of the shots.
6. If you DO start using the different WB settings (as opposed to auto white balance) get in the habit of returning the camera to "daylight" setting after you're through shooting, and check the WB setting EVERY time you start to shoot, to be sure you have it right.
Need more? Just ask.
Robt.
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08/27/2005 04:48:32 PM · #3 |
Originally posted by bear_music:
get in the habit of returning the camera to "daylight" setting after you're through shooting, and check the WB setting EVERY time you start to shoot, to be sure you have it right. |
How to remember to check all those settings?? Andrea finally attached the following sticker to her camera as a reminder:
Looks like my exposure was off. D'OH!
Message edited by author 2005-08-27 16:49:16. |
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08/27/2005 05:10:46 PM · #4 |
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08/27/2005 05:32:23 PM · #5 |
| I tend to use "Auto White Balance" for 95% of pictures. If it's badly off I change it and then change it back right after done shooting in those specific conditions. Incorrect white balance setting is in most cases possible to be fixed pretty easily in Photoshop, for example. |
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08/27/2005 06:52:33 PM · #6 |
| That is a very good tutorial. My problem was I was trying to use a non-dedicated flash unit with my camera indoors and .i was too impatient to think through what I should be doing. I am going to experiment and see what I come up with. I don't think my camera has alot of convenient buttons with the little icons for daylight, florescent and all, so I will have to get familar with it and see what it actual does. Anymore info is completely welcome and maybe it is helping others too. |
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08/27/2005 09:01:06 PM · #7 |
bear_music gave you a good intro, and addressed the color temperature issues. However, some lights have different amounts of each color, and can give you problems. fluorescent has more green light than other sources (and can vary between about 3.5K and 5.5K, IIRC--think "warm white" and "cool white", and special "daylight" fluorescents.)
You can find the color rendition (or rendering) index (CRI) for many light sources (CRI shows how much the bulb approximates a "perfect" bulb), and if you check them, will find that they are all over the place. From //lightingdesignlab.com/articles/cri/cri.htm "Standard incandescent lamps enjoy a CRI rating of 100. Fluorescent lamps are in the range of 52 to 95, depending on the lamp."
If you use fill flash in a room lit by fluorescents, you will find that you get mixed lighting. Some surfaces will reflect more flash (those perpendicular to you) and some will reflect more fluorescent light.
To add to bear_music's point 5, be aware of the time of day and conditions. The color temperature of the sun can vary from about 2K in the morning or evening to 0ver 10K in the middle of the day in shade (shade is different than direct sunlight). A flash is about 5.5K so if you set the WB to flash (with or without using a fill flash) the sunrise or sunset will be more red.
If you want "true" color, it may be best to set the white balance manually, either with a white card or by using the "coffee filter trick" (put a white coffee filter or napkin or similar over the lens, set focus to manual, take a picture and set your WB to that). |
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