Originally Posted by lovingdvd
OK I know for a long list of reasons we are supposed to calibrate with the auto iris OFF even if we do all our watching with it on (which is how I always watch).
But here is the thing I don't get... When I switch between Auto Iris 1 or 2 over to Manual iris, the color temperature changes significantly. It is very noticeable by eye. This is with the same color temperature such as Low 1 or Custom 1 selected.
Try this... Put up a 100% full field pattern with Auto Iris 1 engaged. Note the color of the white. Now move to Auto Iris 2. Note that the color has stayed the same. Now move to Manual iris. As soon as you do, you'll see a noticeable shift in the color of white - this is despite the color temperature selection being the same.
In fact I measured the difference - I have a dE of 0.4 with the auto iris and that dE moves to 9 just as a result of changing to the manual iris. What is causing this??
This puts me in an interesting position. Am I suppose to calibrate a beautiful grayscale and gamma in manual iris mode, only to run in Auto Iris mode where I know the dE is significantly different (wrong)? Before you say yes you can't measure or think of the auto iris fields like that - keep in mind as just one example that a full field 100% flash such as in LOTR 1 would appear wrong in that scenario, among others.
If the 95 is anything like the 60, then each Iris Mode has it's own set of default RGB Gain/Bias values within the Service Menu.
You could check to make sure that all vaules are the same for each of these 3 modes: Off, Manual & Auto 1/2.
I'd have to say that I think that the Auto modes tend to shift the grayscale toward red. So if you don't have enough red headroom, this is likely where those "brightness compression" and "clipping" comments can come into play. but this is easily verified while measuring.
You should be able to determine where you have run out of red when you are balancing your RGB for 100% white (with your Auto Iris engaged). You'll need to back off your Green and Blue gains until you have given yourself a few clicks of headroom. Now your overall lumens may have dropped, but there is the potential option to adjust the . I prefer to set it so that a 100% white measures the same for the Iris OFF. Then go back and verify that this hasn't gobbled up your red headroom again.