REVIEW: BenQ V2400W Part 8
The homogeneity of the brightness distribution was measured at 15 points distributed across the screen after calibration to 140 cd/m²and the largest deviations measured were on the left margin. In the upper left corner, the brightness is 83 percent and therefore deviates from the brightness in the centre by 17 percent. This deviation is within a scope which means that there are no subjectively visible changes in brightness on the screen.
The homogeneity of the backlight on the BenQ V2400w is good.
BenQ’s version of Overdrive, which is used to balance the remaining lag on the already fast panel and this give rise to improved playback, is known as AMA.
The effect can be seen really clearly when a moving coloured object is displayed with sufficiently large mono-coloured surfaces. In this test image, the pentagon moves from left to right. Behind the black outlines, a slight shadow can be seen, which is created by the sluggishness of the individual pixels which were black a short time ago and have not yet achieved the final new colour value.
The shadow on the left beside the black outlines shows the sluggish pixels. The pentagon moves to the right.
If AMA, or Overdrive, is activated, an attempt is made to achieve the final colour hue through an intentional short-term over-steering of the panel.
However, here, the BenQ Overdrive solution overshoots the mark. Thus, not only are the pixels on the left hand side are too bright, but those on the right hand side are darkened. Although the contrast on the line is increased somewhat through the Overdrive, the bright seam on the left hand side is more distracting than the shadow that was visible before. In addition, the shadow on the right hand side is a weak version of the effect that you actually want to avoid using Overdrive. This bright seam of colour is also known as the corona effect, a type of bright afterglow at dark edges.
Fundamentally, the TN panel is fast enough and only a small number of users really need the performance boost. In our opinion, activating AMA does not provide any visible improvement of the image quality.
With Overdrive, the shadow becomes a bright seam.
Our measurement of the period of time until the screen content is actually displayed does not provide a constant value, but instead, differences of between 0 ms to 33 ms. Measured from 30 individual values, the average input lag is 15 ms.
On the left a 21" CRT, on the right the BenQ V2400W. From top to bottom, some of the measurements we took: 0 ms, 16 ms, 33 ms.
Occasional gamers will not notice this much, but in some circumstances, the input lag is too much for professional gamers and may prevent them from being the first to draw in fast-paced shooting games.
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