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Viewing Angles, Uniformity, Response And Lag
To learn how we measure screen uniformity, please click here.
Like many enthusiasts, we long for more IPS- and VA-based options, especially in the gaming category. For now, however, fast refresh models are dominated by TN panel technology. Our photos of the XL2420G show typical red/green shift and light falloff to the sides, and a severe loss of detail as the gamma shifts in the vertical plane.
Screen Uniformity: Luminance
The XL2420G turns in solid performance in our black field test. Any result under 10 percent means you won’t see light bleed with your naked eye. Still, our instruments show a slight hot spot in the center of the screen.
Here’s the white field measurement:
The white field result is almost as good, aside from the same hot spot in the center. Additionally, our C6 meter reports a little less brightness in the top third of the panel. Again, this is not visible to the naked eye.
Screen Uniformity: Color
A 1.72dE variation is extremely small. As with the luminance tests above, you won’t see any issues; just a smooth white tone from one edge to the other. TN-based panels have come a long way in the last two years. They now fall behind IPS only in off-axis image quality. Color and uniformity are pretty much comparable between the two technologies.
Pixel Response And Input Lag
To perform these tests, we use a high-speed camera that shoots at 1000 frames per second. Analyzing the video frame-by-frame allows us to observe the exact time it takes to go from a zero-percent signal to a 100% white field.
Testing a 144Hz gaming monitor means we can’t use our AccuPel generator, since it's limited to 60Hz. Instead, we hook the XL2420G up to a GeForce GTX 780-equipped PC and film a mouse movement that triggers the field pattern’s appearance. Since this is less precise than using the generator, we average five measurements. Here’s the screen draw result:
A two-millisecond gap from first to last means these monitors are essentially identical in their screen response. Even though you can reduce motion blur with the XL’s built-in backlight strobe, it’s barely necessary. And you’ll lose 65 percent of the available light output.
Here are the lag results:
All of these monitors have imperceptible input lag, so even the last-place AOC G2770PQU enables a responsive gaming experience. The XL2420G lands just below the middle at 27ms, which is perfectly respectable. The only real separator here is whether or not the monitor has G-Sync support, which you’ll pay a premium for. Performance-wise, it’s a wash.
