It has been a while since I've posted to this thread, but I have been following it all along. Thank you all so much for your help and your patience. I've made some adjustments to my procedure - put the white card to the right of the yarn instead of in front of it, adjusted shutterspeed until there was no clipping from the white card on the right end of the histogram. The trouble is, when I do that, the yarn appears much too dark. I can adjust the levels in Photoshop so that the midrange colors are lighter, as they should be, but this still leaves harsh, dark, unnatural-looking shadows, not only on the black background, but also on the yarn itself. We really like the black background when it works right, the way it makes colors pop and often shows a subtle reflection. I can expose it so that the yarn looks great on the black background, at least in terms of value / contrast. But color is still off, and if I do this, then the white card is blown out and clipped, and it no longer works properly for WB. Would more lights hitting the yarn from different angles help, or would the additional light on the white card cause the same problem? We have the fixtures, but only the two of those incandescent bulbs that I'm already using, or I would have tried this already. Do you have any other suggestions? Thanks again,
Will