What I have found with the i1 Pro 2 is that while it does not require frequent re-initialization, the low stimulus brightness is drifting quite a bit from the moment is it calibrated till after a couple of minutes.
For example, measuring the display of my HTC One,
- The 0% reading is 0.43cd/m² immediately after calibration but it increases up to 0.55cd/m2 after 3 min and 0.60cd/m² after 5 min and 0.63cd/m² after 10 min.
- White starts at 446.7cd/m², then moved up to 447.6 cd/m² after 5 minutes, when it suddenly drops down to 445.5cd/m2 and seems to stabilize at 445.8 cd/m² after 10 min
- White temperature starts at 7100K and end at 7,190K after 10 min.
If I calibrate the device when it is warmer (after 10 min), then the drift becomes negligible.
- The 0% reading is 0.43cd/m² reading still reads 0.43cd/m² after 10 min.
- White also remains constant
- White temperature drifts only marginally (+20K)
If I recalibrate further along the line (after 30 min of continuous use), temperature continues to drift by 10K within 10 min. Overall the min has been 7100K and max 7230K with 80% of this fluctuation already accounted for after 10 minutes of use.At first I was alarmed by the significant brightness drift at 0% stimulus, but this was because the i1 Pro 2 had to get warmer, so the initial calibration looses its accuracy there pretty quickly. Once the warming up threshold has been reached, the meter initialization holds much better.
Usually only color temperature and brightness are affected by time in operation. Gamut for primaries is usually stable. Note that the temperature drift after re-initialization are probably overestimated in my analysis due to running continuous measures every couple of seconds. Assuming you have a less intensive use with regular inactive time, I expect this drift to be more moderate. Recognizing this is important before any colorimeter profiling is attempted because the white reference is affected.
Has anyone made similar experiences with the I1 Pro 2 or i1 Pro?
Overall it is slightly disappointing that you are not exactly sure where along the line the right color temperature is being measured. Because of the rash drifting in the first few minutes, I have to assume that the more settled readings are the correct ones, since they do not drift as much. But I can't be 100% sure.
50K color temperature is not that important but 130K is not negligible. I wish x-Rite would give recommendations as to which measurement is certified? After how many minutes of operation??
As a comparison, my I1 Display Pro only drifts by 30K.