Question Should I be concerned with whiter than white response?

[youngsyp]

Hi,

I have just bought one of the latest Panasonic 4K LCD panels. Whilst calibrating one of the inputs last week I noted that as the Contrast control moved closer to 100%, whiter than white bars on the test pattern I was using disappeared. This is of course to be expected somewhat but up until now, every panel I've calibrated let me get to 100% without this effect. So what is like to know is, should I be bothered with whiter than white? Or just maximise the Contrast control without crushing peak white (234)?
For reference, I can currently get to about 83% before the right most bar on the Lumagen white ramp pattern 'disappears'.

Paul

 

[Gordon @ Convergent AV]

This behavior is actually more normal than the sort of thing you get on displays where you can't crush white detail. Generally on a decent display the default brightness and contrast settings will be correct if correct signal levels are going in. With a display like yours, where it can output an excess of light, you should leave contrast on default ( as long as it doesn't crush white detail or cause non linear colour response...and it wont). You then use the backlight to adjust how bright 100% stimulus is for your environment.

 

[youngsyp]

Thanks Gordon.

Default for 'True Cinema' is 80. I've set it to 83 and none of the above white bars (above or below white) in the test pattern are crushed. Aiming for 120 cd/m2 peak white the display hits just over 121 (either that or 118 or so using the backlight control).
At 84 it starts to crush the whitest of white bars on the test pattern.
Brightness is at default too.
On the pre-calibration measurements after setting the basic controls there was a bit of an upshift in gamma at around 70 IRE. I wonder if that came from the increase in Contrast...
I might have a go at the Blu-ray input tonight and see how gamma measures with Contrast at default.

Thanks again,

Paul