This brings us to the next important component: light and light bulbs.
Poking around your camera's menus you'll find something called white balance (WB). What the heck is that? White is white, unless we are talking about old gym socks, right?
Light comes in all kinds of colors and if you look at (better yet, measure) it falling on a white surface it will have a certain color to it. This is influenced by the temperature of the light. For example sunlight can vary from 3000K (degrees Kelvin) during sunrise/sunset to as high as 12000K during the brightest part of a day.
A normal household light bulb is around 3400K and a fluorescent is around 4200K. None of which probably means a thing to you right now. But it means quite a bit to your camera and your images. If you shoot images with the camera's white balance set wrong you could end up with a bunch of blue or orange tinted shots, which can be tough to fix.
The best thing you can do is make sure your camera is using the right setting. If we hook up fluorescent bulbs to our soft box we'll want to make sure the camera uses a fluorescent white balance. Or tungsten if we use incandescent bulbs. Doing so will get things pretty close.
Some cameras don't have a white balance setting and attempt to automatically figure it out when you shoot the picture. Other cameras have a mode that does this, called Auto White Balance. Auto WB works in some circumstances, but it can also let you down.
If you have a camera like the Nikon D70 you can also make a preset white balance. On the D70 change to preset WB (hold WB button while turning dial). Then press and hold WB again until you see PRE flash in the top window. Now hold up a white card in front of the lens, with plenty of light shining on it, and press the shutter. The D70 will attempt to calibrate to this new white balance. If it worked you see GOOD in the window, otherwise NO GOOD and you'll have to try again.
The following shots were all taken with the same base camera settings. The main difference was in the source of light. For each source of light the left photo shows how the D70 captured it with white balance set to Auto and the right photo is after white balance was calibrated.
You can see that the last one, with 75 instead of 60 watt bulbs, came in a little brighter than the others. Normally I would have adjusted camera exposure to even them out, but I wanted to keep the settings the same.
You can see that Auto WB didn't do too well. I've also found that matching the WB to the light source (incandescent or fluorescent) still produces off colors. The best overall approach, if your camera supports it, is to pre-calibrate the white balance with a white sheet of paper.
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