Walter Schroeder , Dec 11, 2007; 05:19 a.m.
Ray why do you need a calibration? What is your camera? I am not an expert on this but the experts will want to know :-)
A calibration only gives you an improvement over the calibration "as is" if the calibration is better than the one you got. It is very easy to screw up the calibration. When done correctly it is very likely that there is only a noticeable improvement for one light setup , e.g. for a studio with a certain defined set of lights. Depending on the individual sensor a careful calibration would be beneficial for all shooting but there is more needed than to put a test chart on the table and take few pictures.