Originally Posted by lovingdvd
In theory you are supposed to do it with the Auto Iris off. However I noticed that when the Auto Iris is off, the grayscale measures totally different.
For instance with the Iris set to Manual I used the Custom 1 color temperature to adjust 100% to a dE of 0.6. But when I changed over to Auto1 Iris the dE at 100% measured over 3 with this same color temperature!
After seeing this, and since I do all my viewing with Auto1, I decided to calibrate everything (grayscale, gamma and gamut) with the auto iris on.
When doing gamma I was careful to use full field patterns (very important with the iris on!) and to wait about 3-5 seconds after each pattern change to give the iris time to fully adjust (you can see that sometimes a pattern starts out a bit dimmer and then within a second or so reaches its brightness level).
I do not know if this is technically correct, but I can say that the results look spectacular with test patterns (gray steps, ramps etc) and real world material.
By saying you need to wait 3-5 seconds, I think you already notice that the IRIS do CHANGE from %WHITE. And because of that, you are NOT calibrating GAMMA... Even if you use AUTO-IRIS in normal viewing, calibrating with Auto-IRIS ON will NOT give you the GAMMA you are looking for.
The reason you see 100% WHITE dE difference changed between manual and AUTO-IRIS is likely an artifact of the projector design. In Manual mode, you fixed your IRIS to one fixed aperature, and that aperature if I were to guess, is probably different from the aperature when you are using AUTO-IRIS (I presumed it is fully opened). In an ideal world, the GAMMA and dE should stay the same with ALL aperature openings, but they are more than likely NOT. What I think you can try is to find out the aperature setting of AUTO-IRIS when you project 100%, and then manually set the aperature and then calibrate all the way. Your dE at 100% should now be the same for both.
Basically, consider aperature and %WHITE as a matrix. Aperature say goes from 1-10 (A[1:10]) and %WHITE from 0-100 (W[0:100]). Gamma is a function of W[0:100]) for a fixed aperature (since for every frame, there is only 1 aperature setting). i.e.
example 1:AW, AW, AW.... AW
example 2:AW, AW, AW.... AW
example 3:AW, AW, AW.... AW[100
However, when you use AUTO-IRIS to calibrate, what you are getting maybe something lke AW, AW, A1[W20], A3[W30] ... A10[W100]...So, it looks OK in your graph, but it is not real GAMMA you are measuring.