> Does this occur if you remove the instrument from the screen for > the first 50 measurements, and then place it on the screen ? > (ie. is it a thermal effect as the instrument warms up ?) I think you hit the bullseye here! :) Take a look at the enclosed ResultsFull.txt - the result of leaving the Spyder3 on screen for about 9 hours :)... Open it in any spreadsheet and plot the X data - you will notice a "dog's tail" at the beginning, then, after about 2000 readings, it stabilises. Question to any person who knows statistics - is it possible to write a software for warming up the spyder before commencing read? > If I choose and R=G=B on my display to give a Y of about 0.2, this is what > I get: > Reading X Y Z > 1 0.000000 0.175008 0.124630 > 2 0.000000 0.176625 0.126857 > 3 0.000000 0.177723 0.127206 > 4 0.106032 0.187275 0.159078 > 5 0.106109 0.187766 0.162659 Now this is interesting!!! Have you used the original integration time or did you incorporate my "hack" that was aimed at exactly this problem... Note that Y and Z values are OK whereas X is often a "trash read"... I do not think X is set to zero when it is less than 0.100 - I have managed to see values of about X=0.05 when covering the spyder by hand (I do not have a monitor dark enough to see blacks of such a low level). It was "flapping (switching between zero and 0.05) all the time also the results were very inaccurate (it does not trouble me as the error on X seems to be more than 0.04... All the results were made using the increased integration time. This night I will try to test the response of the Spyder3 to my monitor's black using my hack. The question I want to answer myself is whether I will get any flapping (=hack is useless) or not(=hack is working).