Brightness And Contrast
To read about our monitor tests in depth, please check out Display Testing Explained: How We Test Monitors and TVs. Brightness and Contrast testing is covered on page two.
Uncalibrated – Maximum Backlight Level
The XB271HK is only the fourth Ultra HD gaming monitor we’ve tested, so the group has been filled out with two other excellent screens, NEC’s EA275UHD and ViewSonic’s VP2780-4K. Representing FreeSync is the ViewSonic XG2700-4K and AOC U2879VF. The Acer XB280HK is the first UHD gaming screen we tested and features G-Sync technology.
If you need a super-bright screen, the EA275UHD has the highest output we’ve ever measured. The XB271HK comes in a bit below its claimed 300cd/m2 but it’s still got plenty of punch for any indoor environment we can imagine.
None of these displays have overly deep blacks but the XB271HK tops the list by a comfortable margin. To us, this is of greater significance than sheer resolution.
The XG2700-4K wins the max contrast battle but only by a small margin over the new Acer. Anything over 1000:1 is a win. This serves to enhance perceived sharpness and detail rendering thanks to a wide dynamic range.
Uncalibrated – Minimum Backlight Level
A minimum brightness of 35.9390cd/m2 is a little low for comfortable viewing, but one only needs to up the slider to level five to reach 50cd/m2.
The XB271HK’s black level still looks strong within the group. The VP2780-4K finishes last thanks to a high zero-backlight setting.
Contrast remains solid at 1009.3:1; very consistent performance. There is however a caveat concerning the Contrast slider that we’ll explain below. We ran these first three tests without adjusting any monitor controls but as it turns out, you’ll need to make a couple of changes to correct the gamma and color saturation errors we found.
After Calibration to 200cd/m2
The XB271HK’s black level remains good after calibration despite our reduction of the gamma preset from 2.2 to 1.8. While we would prefer a finer control with more options, the end result is just fine.
We were concerned that lowering contrast eight clicks would have a negative impact on the sequential test, but the value only dropped by four percent, a negligible amount. Obviously the control was set incorrectly at the outset.
ANSI Contrast Ratio
This is an excellent ANSI result and demonstrates the high quality of the AU Optronics panel used here. If not for a slight hotspot in the lower-right zone, the result would likely have topped 1000:1.