In our
responsiveness article we explore the key factors affecting monitor responsiveness. One of the key concepts explored here is ‘perceived blur’, which is caused predominantly by the movement of your eyes as you track motion on the screen. It is also influenced by pixel responsiveness, although this is generally a less significant (but still important) factor on modern monitors. We also explore ‘pursuit photography’, a technique which uses a moving camera to capture motion on a monitor in a way that reflects both of these elements of perceived blur. This is something that normal static photography or video can’t capture.
The following images 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 taking such photographs and highlights both key elements of perceived blur. The UFOs move across the screen from left to right at a frame rate matching the refresh rate of the display. The monitor was tested at 60Hz (directly below) and 75Hz using all ‘Overdrive’ settings; ‘Off’, ‘Weak’, ‘Medium’ and ‘Strong’. All rows of the test were used, with the backgrounds showing various shade levels (dark, medium and light). The final column shows a fast TN reference screen (
Dell S2417DG) set to 60Hz, showing how things look where pixel responsiveness isn’t really a limiting factor.
At 60Hz, shown above, the UFO appears relatively soft and unfocussed. This reflects a moderate level of perceived blur due to eye (camera) movement, with this element also shown on the fast TN reference. There is also some trailing behind the UFOs in some cases. With ‘Overdrive = Off’ it’s clear that the name is misleading, as effective pixel overdrive is used – it just happened to be the lowest level of this available on the monitor. There is no conventional trailing visible behind the object, there is instead a small amount of overshoot (inverse ghosting). You can see a slight bright fringe (halo trail) behind the UFO, but this blends in well. The ‘Weak’ setting ramps up the pixel overdrive and slightly increases the overshoot levels, although this remains quite weak. The ‘Medium’ setting strengthens the overdrive further and overshoot becomes more noticeable, whilst the ‘Strong’ setting provides strong, colourful and obvious overshoot. From this analysis and our broader analysis outside of this test, we consider ‘Off’ to be optimal at 60Hz. Although ‘Weak’ is also very useable, making limited difference to the pixel response behaviour. Below you can see what happens when the refresh rate is increased to 75Hz.
At 75Hz, shown above, the UFO remains relatively soft and unfocussed although is somewhat narrower than at 60Hz. This reflects a slight reduction in perceived blur attributable to eye movement. There is again some trailing behind the object in some cases. The ‘Off’ setting now has no visible overshoot. There is just a faint whiff of powdery trailing for the dark background (top row), virtually none for the medium background and nothing to speak of for the light background. The ‘Weak’ setting makes little difference to this, perhaps reducing the powdery trailing a tiny bit and also introducing a little overshoot for the light background. But this is very faint. The ‘Medium’ setting increases overshoot and introduces a slight dark trail behind for the medium and light backgrounds as well as a slight dirty overshoot trail for the dark background. The ‘Strong’ setting ramps up the pixel overdrive and introduces obvious overshoot.
There was a moderate level of perceived blur on Battlefield 1 (BF1), but this was almost entirely attributable to eye movement and limited by the refresh rate of the display rather than pixel responses. Compared to 60Hz (at 60fps), the 75Hz refresh rate (at 75fps) gave a slight decrease in perceived blur which helped keep things just a bit sharper during rapid movements. There was also an edge in ‘connected feel’, which describes the fluidity and precision as you interact with the game world. There was very little to complain about in terms of pixel responsiveness, in stark contrast with the older Q3279VWF. There was a very small amount of faint powdery trailing in places, for example where dark objects such as tree trunks in a shaded area moved against brighter objects such as the sky. This was not eye-catching, not widespread and was only a very minor contributor to perceived blur. Likewise, there was a very small amount of overshoot in places. What we like to call ‘snail slime trails’ with the trailing appearing like a slightly lighter semi-transparent variant of normal trailing. Most prevalent but still very faint where brighter shades moved against medium shades (a white painted wall against the sky, for example). Even users sensitive to overshoot shouldn’t find this bothersome and most users wouldn’t even notice it even if actively looking out for it.
Shadow of the Tomb Raider told a similar story. And this was again one of a solid 75Hz performance with only minor weaknesses in places. Again, slight traces of overshoot and faint powdery trailing for select transitions, but very little to complain about. The edge in refresh rate and frame rate comparing to a 60Hz monitor at 60fps was again welcome due to the slight decrease in perceived blur and increase in ‘connected feel’. Obviously, this was not at the level of higher refresh rate models with triple-digit refresh rates running at suitable frame rates, but it was a nice edge nonetheless. We also observed a variety of movie content, including ~24fps Blu rays, ~30fps Netflix content and ~60fps YouTube content. The content at the lower end of that frame rate range in particular was limited in its fluidity by the frame rate itself and the pixel response requirements for good performance are not as stringent as for higher frame rate content. None of this content revealed clear weaknesses in terms of pixel responsiveness from the monitor, however.
