I use my D40 frequently to take pictures of jewelry using a white background and 5000K CFL lighting. Seemingly regardless of what settings I use, Auto or P, flash or no flash, the white background comes out a dirty gray. What am I doing wrong or what settings should I be using?
The auto exposure system is designed to render scenes averaging to a medium gray. The camera does not know that all that white is supposed to be white. You need to use some +EV to get more light or do the same thing using manual exposure.
---------+---------+---------+---------+ Joseph K Seattle, WA, USA
Use manual or aperture priority. Expose so the histogram is up to the right side. Shoot RAW and adjust your white balance and exposure in post processing. The white background is causing the camera's meter to underexpose.
Since the background is gray in the image and white in reality, the images are under exposed. Dialing in some positive Exposure Compensation should solve the problem. As stated a above, when the background is white or brighter than the subject, the cameras metering system tends to under expose when Matrix or even Center Weighted metering is used. Depending on the subjects size, using Spot Metering should be more accurate. Good Luck and Enjoy your Nikons!