I just spent several days calibrating grayscale and then gamma on my JVC RS20 projector, and after spending hours on gamma trying to get the individual R/G/B dialed in I thought I had a nearly perfect flat 2.4 gamma with only a couple of drifts at 10 & 90 IREs on R/B, as well as a near perfect grayscale, almost all <1. BUT, then last night I was basically just going to do a final touchup trying to tame those drifts as well as I could.
After placing the meter in front of the screen again I felt like I got my heart ripped out of my chest when I did a 10pt grayscale test with the same settings I left off with the night before, and both grayscale & gamma were suddenly completely different from what I had just the day before. I then spent a good hour or more just trying to place the meter in different locations to find a good location both trying to get the best Y cd/m values and to see if I could get back to similar grayscale dEs as I had the day before, but no. And not only did I get different results compared to yesterday, but noticed that depending on how I placed the meter I got different dE's & overall data, with R/B values shifting as well depending on location.
I've read different tips that you should try to point the meter close to the viewing angle, and of course try to maximize Y, which is what I did the first time, while of course trying to avoid the meter measuring its shadow on the screen, and I set it up similarly last night as well, but like I said keep getting different data.
I've attached the HCFR files with the results after the calibration, and then from last night from 2 different positions using the exact same settings, but with different results.
As already mentioned, I'm using HCFR, set to rec709 & the recommended color CIE, and using an X-Rite i1Display Pro colorimeter.
Also doing all measurements in as dark as the room gets at night, with no lights on, and we watched a full 2h movie before even starting calibration, so the pj is fully warmed up, and also since I spent an hour+ monkeying with meter placement the meter should certainly be warmed up as well.
Now, I do have a bit of an unusual HT setup, since we're currently using a temporary setup with the pj placed on a nightstand ca 2ft up from the floor behind us, which probably makes it trickier than for most to place the meter in a good spot without getting shadows behind it, not sure if that has something to do with the poor accuracy/consistency I'm getting?
I could definitely use some help & tips on how to get better & more consistent results, since right now I'm not even sure if there's any point calibrating at all if I can't get the same results from one day to the next
Not sure what I can do to fix this?!
Incorrect meter placement?
Maybe incorrect HCFR settings?!
Bad meter? But during a single calibration session I seem to be getting decently consistent results, since I can adjust grayscale gain/offset & gamma RGB values and get it dialed in pretty well.
I've also attached a picture showing how I ended up placing my meter yesterday, I know it probably looks like the meter is pointing right at the shadow in the picture, but it's actually pointing to the left/center of the shadow.