REVIEW: Samsung S27A850D Part 7
We carried out measurements on the S27A850D in its native resolution at 60 Hz via the DVI connection. The monitor was restored to its factory settings for the measurements.
We measured the image display time for a black-white change and the best grey-to-grey change. We also found the average value for our 15 measuring points.
The data sheet indicates a response time of 5 milliseconds (GtG). When it comes to the three-level overdrive option (German: "Reaktionszeit"), the middle level "faster" is active in the factory settings. In this setting, we measured 11.9 milliseconds for a black-white change and 11.5 milliseconds for the fastest grey change. The average level for our 15 measuring points is 14.4 milliseconds.
‘Faster’ response time: Average switching times, no overshoots yet.
Our investigation of the luminance gradient shows that this overdrive level still just about manages with no overshoots. The switching times reflect what can be ach8ieved with modern PLS/IPS panels in a neutral profile. This setting is ideal for games of normal speed and for watching films.
Things move a little faster in the "Fastest" setting. Although the switching times are only 15 percent shorter, clear overshoots now arise – evidently, it is not possible to get more out of PLS/IPS panels. There is not yet any great danger of noticeable side effects arising in fast-paced film scenes, for example, but this setting can only bring about a slight advantage for very fast-paced games.
‘Fastest’ response time: only slightly shorter switching times, clear overshoots.
The lag is a significant value for gamers and we measure it as the sum of the signal delay time and half of the average frame rate. On the S27A850D, we measured a relatively long signal delay of 13.6 milliseconds, which will not please the very committed gamers among us. A further 5.7 milliseconds pass until the target luminance is reached and therefore, the average total lag is not as short as expected, reaching 19.3 milliseconds.
Investigation of the LED backlight on the S27A850D requires interesting technology: the backlight glows almost continually at full luminance (regulator setting 100, red curve on the chart), but we also see overlaid timing, with an amplitude of about 8 percent. When the level is halved to the 140 cd/m² suitable for a workspace (yellow curve), the power consumption of the LEDs in particular is halved and the clocked share increases by more than 30 percent.
The clock rate is 180 Hz and the duty cycle is 63 percent. Despite the nominal agreement, these values should not be interpreted as they might be in cases of pure PWM control: in fact, even very sensitive users should only notice backlight flickering at the very lower end of the luminance regulator.
LED backlight with combined power and PWM control.
In the practical test, no unusual trailing effects or motion blurring could be observed in simple games and videos. Even when fast movements are depicted, the image still looks very clear and in the PixPerAn legibility test, we were able to reach Level 8 and even Level 9 multiple times without difficulty, which is a very good value and is hardly achieved even by good gaming monitors.
Even when fast movements are displayed, streaking is at a very good level. Ambitious gamers may be disappointed with the somewhat slower response time. Here, fast gaming monitors are around 10 milliseconds faster. On the other hand, this monitor impresses users with a very detailed, colour-intensive image.
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