At last! I finally solved a problem that I've been having with photography for a long time. Red cloth always "washes out", looking overexposed and flat. The subtlety of my color gradations is usually completely destroyed.
The quick answer is this: switch the camera to raw mode.
And here's why...
When a camera is not in raw mode, using something like "Fine", its tiny computer interprets the values coming from the sensor and flattens them into a jpg. When it does this, it uses its own algorithm to determine how important each color channel is. These algorithms are developed to make most photos look good. And most subjects in the natural world don't contain much red. Therefore, the red channel is not given much importance when the jpg is assembled. If a subject is predominantly red, it messes up the camera's algorithm, resulting in red values that are oversaturated and flattened. And this all happens before the image leaves the camera, so there's nothing that can be done to fix it. The "shades of red" just aren't stored in the image and nothing can bring them back.
When a camera is in raw mode, it stores the actual values captured by the camera sensors into the image file with no interpretation whatsoever. The image manipulation software on the computer can decide how to interpret the separate color channels and combine them into a finished image.
I use Aperture, which has built-in features for interpreting raw images. It gives me control over every aspect of how the channels are combined into the final image. The end result is that I can finally take photos of my red cloth and have these photos convey the subtle color gradations that I work so hard to create in my cloth.
Oh, yeah, and I finally got the studio lighting set up in a way that emphasizes the cloth and makes it pop forward from the dark backdrop. I'll write more about my setup in a day or two.