ViewSonic VP2468

Responsiveness

Input lag

We used a small tool called SMTT 2.0 and a sensitive camera to compare the latency of the VP2468 to a range of monitors of known latency, taking over 30 repeat readings to maximise accuracy. Using this method we calculated 4.40ms (under 1/3 of a frame @60Hz) of input lag. Note that the value here is influenced both by the element you see (pixel responsiveness) and that which you feel (signal delay). This indicates a low signal delay on the monitor which even sensitive users shouldn’t take issue with. Enabling the ‘Low Input Lag’ mode did not have a significant effect on this value, perhaps lowering it by a fraction of a ms simply due to the more aggressive pixel overdrive employed.

Perceived blur (pursuit photography)

In this article we explore some important concepts related to monitor responsiveness. Chief amongst these is the notion of ‘perceived blur’, which is influenced by both the pixel responsiveness of the monitor and the movement of our own eyes as we track motion on the screen. This second part is the more significant factor on modern LCDs. We also introduce ‘pursuit photography’, which uses a moving camera to capture motion on a monitor in a way that reflects not only the pixel responses of the monitor but also the movement of the eye (camera). This gives a much more accurately representation of what the eye sees at a given moment in time than any photography method which uses a static camera.

The images below are pursuit photographs taken using the UFO Motion Test for ghosting, with the test running at its default speed of 960 pixels per second. This is a practical speed for such photographs to be taken. The monitor was set to run with ‘Response Time’ set to various settings; ‘Standard’, ‘Advanced’ and ‘Ultra Fast’. We’ve also included a shot taken with the monitor using ‘Advanced’ and also the ‘Low Input Lag’ setting, which alters pixel response behaviour. The medium cyan background (middle row of test) was used for these shots. The final shot is taken from a Samsung S27A750D running at 60Hz, full brightness (avoids PWM) and using its optimal response time setting for 60Hz. This represents how things should look where response time isn’t really a limiting factor and it’s only eye movement that would come into play for the perceived blur.

Perceived blur with various settings

Using ‘Standard’ provides a weak level of acceleration. There is significant blurring of the object itself due to eye movement and also a bold trail behind the object – remember that the object moves across the screen from left to right. The ‘Advanced’ setting reduces this bold trail significantly. There is now a small amount of overshoot (inverse ghosting) behind the cockpit in particular, but it’s very light and difficult to see. The ‘Ultra Fast’ setting is actually rather similar to this, with slightly stronger overshoot. When activating the ‘Low Input Lag’ mode, the level of overshoot increases considerably. For this example we’ve kept the Response Time in ‘Advanced’, where you can see a bright and colourful trail behind the object. If you use ‘Standard’ with this low input lag mode then performance is extremely similar, whilst using ‘Ultra Fast’ with this mode gives overshoot that is even stronger.

Our analysis here suggests that the ‘Advanced’ setting (without ‘Low Input Lag’ active) is optimal. Indeed, the signal delay is already very low, so this mode is really just detrimental to image quality without any noticeable advantage. This is echoed by general testing as well. The ‘Ultra Fast’ setting provides only a little extra overshoot, but it doesn’t really provide any noticeable advantage either. So the ‘Advanced’ setting certainly seems best balanced on this monitor. Note that we will not be analysing the overclocking performance of this monitor, because as mentioned previously there were very obvious interlacing patterns on some shades when running the monitor at higher refresh rates such as 75Hz.

Responsiveness in games and movies

On BF4 there was a moderate amount of blur. This was caused predominantly by eye movement and largely similar to what you’d observe on even the fastest 60Hz LCDs. The pixel responsiveness was largely fast enough for optimal 60Hz performance, with most pixel responses being masked by perceived blur from eye movement. There were some subtle weaknesses here and there, but nothing that really stood out. Some higher contrast transitions were performed a bit slower than optimally. This was particularly the case where light objects moved against a dark background, such as light metal against a stormy sky. Even then the additional trailing was quite light. Rapid movement involving such transitions (for example driving an ATV in dense shaded vegetation) produced a little extra perceived blur as a result. There was also a little bit of overshoot (inverse ghosting), particularly during some medium transitions such as tree trunks moving against a light blue sky. This produced some faint bright trails that were slightly lighter than either the object or background colour. These were not obvious, though, they were too subtle for most users to notice.

On Dirt Rally there was a moderate degree of blur, again caused predominantly by eye movement and much as you’d see on even the fastest 60Hz LCDs. There were no obvious weaknesses imposed by slower than optimal pixel responses – just the little bit of extra trailing during some transitions that is barely noticeable really. When driving at night, for example, there were some slower than optimal pixel transitions which slightly increased perceived blur during rapid cornering. Even in a side by side comparison with a snappy TN model running at 60Hz, though, the difference can only be described as subtle. There was no obvious overshoot, either, just very light traces during a minority of transitions that wasn’t at all eye-catching.

As noted earlier in the review our Blu-ray drive wasn’t working, so we couldn’t perform our usual responsiveness assessment using these. We did observe some movie trailers and Amazon Prime movie content, however. There were no obvious weaknesses here. The same subtle weaknesses could be seen as we observed for gaming, when viewing 60fps content; nothing to write home about. For typical content (24 – 30fps) these weaknesses weren’t even apparent, masked by imperfections in fluidity and overall pace of action imposed by the low frame rate itself.

Conclusion

The ViewSonic VP2468 is a monitor marketed as a budget photography screen, and it certainly ticks a lot of boxes for such a screen. Straight from the box, the colour performance was pleasing. Gamma tracked tightly to the desirable ‘2.2’ curve and white point was within good range of the 6500K (D65) target. The AH-IPS panel also provided strong colour consistency, which when coupled with complete coverage of the sRGB space (and a little coverage beyond, natively) gave an excellent rich and varied look to the image. The VP2468 also included a rather comprehensive OSD, with many useful (and some not so useful) presets as well as various other settings to fine-tune according to preferences or taste. Some of these presets are factory calibrated ‘Color Mode’ setting and include a degree of colour space emulation as well as correction of gamma, white point and other key attributes.

The ‘sRGB’ setting, for example, cut back on the native gamut a bit but actually gave a little under-coverage. Users may prefer to use the full native gamut (100% sRGB) when calibrating to ensure full shade coverage within the sRGB space. The monitor also includes a hardware-addressable LUT (i.e. supports hardware calibration) which can be addressed using a compatible X-Rite colorimeter such as the i1Display Pro. To further enhance potential desirability for those interested in tight colour accuracy, a Uniformity Compensation setting is also included. This certainly provided excellent luminance and colour temperature uniformity, according to our testing. It did come at a great expense of contrast, though, which may or may not be a worthy trade-off depending on your work. One slight niggle, and not one entirely unique to this panel, is that we could observe interlacing on some shades such as blues and oranges. This was fairly faint (at 60Hz), but still visible and could be a potential bugbear for users who like to closely inspect their work for noise or other artifacts. Or are simply sensitive to such things.

The monitor put in a reasonable but not particularly special contrast performance. Obviously, as an IPS panel, we were fully expecting ‘IPS glow’ and reasonable contrast rather than anything outstanding. But the static contrast recorded even natively was somewhat lower than what we’ve seen on quite a few IPS-type panels recently and fell short of the specified 1000:1 (at closer to 800:1). In practice this doesn’t make a huge difference, but we could observe a bit of detail loss in dark scenes when gaming primarily as a result of this slight weakness. The screen surface didn’t impede our enjoyment of lighter shades to the extent that it did on some other models, particularly older IPS models and some recent TN models. There was still a bit of graininess (slightly more than competing PLS models, in fact) but nothing particularly obtrusive.

The responsiveness of the monitor was pleasing overall, within the confines of the 60Hz refresh rate. Trying to ‘overclock’ this caused the aforementioned interlace pattern artifacts to become very pronounced. There were only some subtle weaknesses in pixel responsiveness, such as a little bit of extra trailing here and there and a small amount of light overshoot. None of this was eye-catching, though, and the performance was largely as you’d see on even the fastest and ‘best tuned’ 60Hz models. There was little input lag to speak of, too, despite the monitor including a largely useless ‘Low Input Lag’ mode. Enabling this had no significant positive effect on input lag and simply introduced obtrusive inverse ghosting instead.

So in terms of its feature-set and overall performance, the monitor is not perfect but still ticks a lot of boxes. When you couple that with the rather decent asking price, it certainly becomes a more attractive proposition. Add to that the solid build and understated yet in some respects quite stylish design, and you do have a monitor that’s worth considering.

The bottom line; a competent budget photography screen and all-round performer with plenty of settings to tweak and some good factory-calibrated presets for a variety of uses

 

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