Ethan Hansen wrote:
A simple-stupid approach would be to manually click the measure button on the lino until you get bored. Do enough measurements in a row and you'll burn off the crud.
I'm not sure. I did a series of experiments with the i1pro, making multiple measurements with about 5 seconds gap between them. I did 50 measurements, and then "cleaned" the bulb between each test. My test was to do consecutive spotreads from cold. In a "clean" state the delta E would rise to about 0.07 - 0.08 before stabilizing warm. An obvious "dirty" effect was for the delta E to rise to 0.15. (I didn't push on to see how bad it could get, or what was needed to get it to reach 2.0 again). Very short measurements (i.e. normal spot read is about 0.25 seconds), seemed to have little effect, although maybe they have an effect over many more measurements (1000's ??). 1.0 seconds seem to "dirty" the lamp moderately fast, 5 seconds seeming to be noticeably worse again, with only 30 measurements being enough to cause obvious effects, while 10 seconds seemed to have little effect. So my current guess is that the lamp has to be on for for about 10 seconds or more at a time to do some good cleaning up, but I'd imagine that doing this test again with no gap between the measurements would yield different results, with less severe dirtying, and cleaning starting at shorter length measurements. My diagnosis test consists of doing consecutive spot reads, and any cleaning effect during that was so small as to be not noticeable. [ Perhaps my i1Pro2 got unusually bad because I was doing a mixture of measuring very small charts (4 patches in a row), and experimental spot measurement times of 1.0 seconds. ]
As an aside - we have seen signs of the behavior Graeme mentions where L* drifts with repeated manual measurements. In our case, it was on Spectrolinos used for quick, manual spot measurements comparing putatively identical colors on different pages of a printer profiling target set. When we did a routine cal check on these two linos, they had drifted significantly, particularly considering that neither one had made more than 75 or so measurements since the last calibration check.
I think that when running on a spectroscan, the increasing L* error will disappear after a few reads (10-20 and a re-calibrate), as a steady cadence of spot reads seems get it into temperature equilibrium. A steady cadence of longer measurements (5-10 seconds) on the i1Pro doesn't stabilize - the L* starts dropping steadily as the lamp dirties up. Of course when it's clean to start with, there is much less variation with cadence. Graeme Gill.