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.
The pattern generator is placed at the base of the monitor so our camera can capture the precise moment its front-panel LED lights up, indicating that a video signal is being received by the monitor. With this camera placement, we can easily see how long it takes to fully display a pattern after pressing the button on the generator’s remote. This testing methodology allows for accurate and repeatable results when comparing panels.
Here’s a shot of our test setup. Click on the photo to enlarge.
The brighter section of the camera’s screen is what actually appears in the video. You can see the lights of the pattern generator in the bottom of the viewfinder. We flash the pattern on and off five times and average the results.

BenQ does't market its PG2401PT to gamers, and gamers probably won't spring for such a pricey 24" display. But this is one of the fastest IPS-based screens we’ve tested, even still.
Here are the lag results:

The lag result also lands on the faster end of the IPS-based field we've measured. Speed is not the PG2401PT’s primary purpose. However, compared to our other pro-class screens, only the Samsung achieves lower input lag.
- BenQ PG2401PT 24-inch IPS Color-Accurate Display Review
- Packaging, Physical Layout, And Accessories
- OSD Setup And Calibration Of The BenQ PG2401PT
- Calibration With Palette Master
- Measurement And Calibration Methodology: How We Test
- Results: Brightness And Contrast
- Results: Grayscale Tracking And Gamma Response
- Results: Color Gamut And Performance
- Results: Viewing Angles And Uniformity
- Results: Pixel Response, Input Lag, And Blur Reduction
- BenQ PG2401PT Demonstrates Amazing Out-Of-Box Accuracy
mixed with the convenience for manufacturers of making mostly
1080 screens. When I hunted for a 2560x1600 screen last year,
I was shocked at the prices, because the same thing has happened
at 2560, ie. the market has narrowed in on 1440 height instead of 1600,
so the latter are now expensive (assuming one can find them at all),
eg. the Iiyama XB3070WQS-B1 is about 700 UKP, and the HP Z30i
is more than 1000 UKP.
At the least one positive from all this is that good 1200-height IPS
panels are now much more affordable. My first 1920x1200 IPS was
an HP LP2475W which cost about 450 UKP, but today the Dell U2412M
costs less than half that much (is the Dell better? Well, yes & no,
different feature set, etc., but the screen is nice).
I gave up on finding an affordable IPS 2560x1600, and meanwhile it
was obvious review sites had settled on 1440 height anyway (a few
years ago many sites were still testing wtih 1600 screens, but not
now), so I bought a Dell U2713HM instead which works pretty well,
except for its irritating resolution limitation over HDMI (watchout for
that if you buy a new screen, some models only support their max
res via DVI or DP - the Dell I bought can't do more than 1080 via HDMI).
Ian.
In case you didn't know, BenQ is the parent company of AU Optronics, which is one of the largest panel manufactures in the world. Other companies (Samsung, Dell, Apple, etc.) use AUO panels in some of their products.