> Keep in mind that any relatively inexpensive emissive instrument is going to > have problems in reading extreme low light, that's the hallmark of > inexpensive. I was once told by Danny Rich that, what we're asking is for > the instrument to read practically no light -- very difficult to detect few > photons reliably. So, personally, anything below 1 cd/m2 I tend to take with > a grain of salt. Thank you for your comment Roger! I was not referring to inaccuracy of the instrument (which is obvious) but rather to erroneous reading - once in about 10 measurements you get a result which is plainly wrong. This might be the reason of getting unsatisfactory results with the calibration (obviously the #1 reason is the cra**y Hyundai N220W LCD monitor I have :) ). Using original code I get error of about DE=17.... I will not present the results from mine as I need to test it further (so far the result is so bad I do not believe a single bit of it: DE=3970 (yes, that is three thousand nine hundred and seventy) - I suspect that I have made a mistake at placing the sensor - no monitor in the world is THAT bad :). > But thank's for your code modification for the Spyder3. Careful! It was only a proposal - I can certainly hope someone who owns a Spyder3 would be able to confirm that the problem really exists first. From my first tests, my change improves the accuracy but some more time is needed to find a suitable multiplyer (I think something like nframes *= 8 upto nframes *= 16 works well. I tried nframes *= 32 but the results were no better. I could really use a little bit more feedback on this - c'mon Spyder3 owners! I know you are lurking here :)