Dell U2417H (U2417HA)

Responsiveness

Input lag

We used a tool called SMTT 2.0 and a sensitive camera to compare the latency of the U2417H (U2417HA) with a range of monitors of known latency. Over 30 repeat readings were taken to maximise accuracy. Using this method we calculated 5.15ms (under 1/3 of a frame @60Hz) of input lag. This value was not altered by using the ‘Game’ preset, but was significantly higher (>20ms) when the monitor was set to run at a non-native resolution. This explains the discrepancy between our reading readings on other reviews where the monitor was not running in its native resolution. The value here reflects both the element of responsiveness you feel (signal delay) and that which you see (pixel responsiveness). It indicates a low signal delay that shouldn’t specifically interfere with the experience even for sensitive users.

Perceived blur (pursuit photography)

In this article we explore the key concepts related to monitor responsiveness. One of the most important concepts explored here is ‘perceived blur’ and how it is influenced not only by pixel responsiveness but also eye movement as you track motion on the screen. Your eye movement is actually the most significant of the two factors for a modern sample and hold LCD monitor. We also explore ‘pursuit photography’, which is a technique that uses a moving camera to reflect not only the pixel response behaviour but also the influence of eye (camera) movement.

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 and reflects perceived blur nicely. The monitor was set to run with ‘Response Time’ set to both ‘Normal’ and ‘Fast’. The medium cyan background (middle row of the test) was used for both response time settings. We’ve also included a capture of the light cyan background (bottom row of the test) with the ‘Normal’ setting just as a point of comparison. A shot is also included from a fast 60Hz reference – a Samsung S27A750D running at 60Hz and at full brightness (avoids PWM usage). This represents how things should look where pixel responsiveness isn’t really a limiting factor.

Perceived blur with various settings

Regardless of the ‘Response Time’ setting, you can see that the object itself is quite blurred and the details indistinct. This is also the case to a large degree with the reference screen. This reflects perceived blur due to eye movement and is strongly linked to the 60Hz refresh rate. Using the ‘Normal’ setting, you can also see a bit of trailing behind the object. This is from slower than optimal pixel responses. The slightly more noticeable trailing that is observed more strongly with the light cyan background takes on a bit of a dirty appearance, particularly behind the UFO cockpit. This is actually overshoot (inverse ghosting) due to fairly strong grey to grey acceleration being used to try to speed up these pixel transitions. The ‘Fast’ setting creates far more obvious overshoot, leaving a colourful inverted trail behind the object itself that is very obvious by eye. Needless to say the ‘Normal’ setting is optimal on this monitor. Note that this monitor skips frames if the refresh rate is set at all above 60Hz. We will therefore not be including a section on overclocking.

Responsiveness in games and movies

On BF4 you could perceive a moderate amount of blur. This was predominantly down to eye movement and linked to the 60Hz refresh rate. There were also some slight weaknesses in pixel responsiveness evident, particularly where certain medium shades were involved in the transition. Many objects moving against a slightly gloomy sky, for example, were accompanied by a bit of trailing in addition to the blur perceived due to eye movement. This was by no means extreme and was quite different to the sort of extended or ‘smeary’ trail you’d typically see on a VA panel during some transitions. It was enough to intensify the already moderate blur when manoeuvring quickly in a vehicle. There was also a little overshoot (inverse ghosting) in places. For the transitions we observed on this title it was usually quite faint and appeared as a sort of mostly transparent ‘snail slime’ behind some objects. This sometimes had a slightly dirty quality to it similar to that seen in the UFO Motion Test for ghosting earlier. Certainly not the most obvious overshoot we’ve seen, but there nonetheless.

On Dirt Rally there was again a fair amount of blur, caused predominantly but not entirely by eye movement. The was an additional ‘mask’ of blur from some slower than optimal pixel transitions – fairly subtle overall. There was no eye-catching overshoot, for example bold bright trails or very dark trails that were a significantly different shade to either the object or background colour. Instead the overshoot manifested itself as a slightly dirty looking blend of the object and background colour in places. So this was not particularly eye-catching as far as overshoot goes. We also tested the Blu-ray film titles and didn’t find any impedance from pixel responses or any obvious overshoot. The ~24fps at which the films run was the main limit to fluidity there and the monitor handled such content as well as any 60Hz monitor really.

Conclusion

The slim-bezelled Dell U2414H was a popular choice and remains that way even today. With the UltraSharp U2417H (and U2417HA reviewed here), Dell have made some slight improvements and aesthetic tweaks. Most noticeably the bezels are now even thinner – as thin as we’ve seen on any screen, lending themselves very nicely to multi-display setups. There are also some improvements when it comes to core performance. The PLS panel used here offers a slightly lighter matte screen surface, which although not as smooth as some does provide a slightly smoother view of lighter shades such as white. When it comes to colour reproduction, there was really little to fault with the factory calibration. White point was within good range, there was no particular tint, gamma tracking was excellent and the overall richness and consistency of colours was very good.

The contrast performance was largely in-line with the predecessor with static contrast that is about as good as you can expect from an IPS-type panel. The ‘PLS glow’ observed here ate away at some of the detail for dark shades peripherally and was a bit more obvious than the ‘IPS glow’ seen on the U2414H and some other models. This difference, we feel, isn’t something that’s worth stressing about though. Responsiveness was similar if a little weaker than the earlier model, too. There was little input lag to speak of, which is good, and overall the level of perceived blur was much as you would hope for from a 60Hz LCD. There were some weaknesses beyond that, such as a bit of extra blur due to slower than optimal pixel transitions and some slightly ‘dirty’ overshoot trailing in places. As with the ‘IPS glow’ vs. ‘PLS glow’, the predecessor had a slight edge but it isn’t something we think you should let put you off the newer model.

All things considered the Dell U2417H (U2417HA) is a worthy follow-up to the U2414H and standing on its own merit offers good all-round performance. The factory calibration is very strong and colour reproduction within the sRGB colour space is a definite strength here. Useful ‘Low Blue Light’ type settings are also found and the backlight maintains flicker-free status throughout the brightness adjustment range. The design of the monitor is also simple yet endearing, particularly with respect to the exceptionally thin bezels that are barely there at all. We also think it’s nice that Dell are offering the monitor in a configuration with an arm rather than conventional stand, although we didn’t really find this advantageous for our uses. The stand includes all of the ergonomic flexibility we would need from a monitor already. Plus, there are a range of other options that you can mount the screen to anyway thanks to VESA compatibility.

The bottom line; a screen with excellent colour performance straight from the box and attractive aesthetics, combined with good ergonomic flexibility.

 

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