AOC C3583FQ

Responsiveness

Input lag

A small utility called SMTT 2.0 was used alongside a very sensitive camera to analyse the latency of the C3583FQ. To ensure good levels of accuracy, we took 30 repeat readings using a range of monitors of known latency to compare. Using this method, we calculated 5.88ms (under 1 frame at 160Hz) of input lag. This value is influenced both by the element you ‘see’ (pixel responsiveness) and the element you ‘feel’ (signal delay). It indicates a low signal delay which contributes to the ‘connected feel’ of the monitor, as we explore later.

Perceived blur (pursuit photography)

In this article we explore the key factors that affect the responsiveness of a monitor, chief amongst which is the concept of ‘perceived blur’. The movement of your own eyes as you track motion on the screen is actually the most significant contributor to this, whilst the pixel responsiveness of the monitor generally plays a more minor role. How minor this role is does of course vary between different models, with VA panels such as this one generally held back most in this regard. Both constituents of ‘perceived blur’ can be captured by using a photography method explored in the article called ‘pursuit photography’, which uses a moving camera to simulate eye movement whilst also reflecting the pixel transitions of the monitor.

The following images are pursuit photographs taken using the UFO Motion Test for ghosting. The test is set to run at 960 pixels per second, a practical speed for taking such photos. The monitor is set to various refresh rates (60Hz, 144Hz and 160Hz) with its ‘Overdrive’ setting at all possible positions; ‘Off’, ‘Weak’, ‘Medium’ and ‘Strong’. The middle row of the test (medium cyan background) and top row (dark cyan background) are both used to demonstrate the influence that the grey level of the shade can have on pixel transition speed. The final column in the image shows some reference shots. The first of these is a Samsung S27A750D set to 60Hz, full brightness (eliminates PWM) and using its optimal response time setting. The second reference shot is taken from a Dell S2716DG running at 144Hz, using its optimal response time setting. Both images show what things look like at a given refresh rate where pixel responsiveness isn’t a limiting factor, save for a little overshoot (inverse ghosting) on the Dell.

At 60Hz, shown in the top two rows, there is a significant amount of blur. The object itself (UFO) appears soft, blurred and relatively wide due to limitations in refresh rate and hence greater perceived blur from eye movement. There is also a fairly bold trail behind the object itself (the UFOs move from left to right on the screen) from sluggish pixel responses. The trailing is more pronounced for the dark background, as the pixel responses are slower here. There’s also obvious overshoot due to excessive voltage surges to speed up pixel transitions using the ‘Strong’ setting. This manifests itself as an obvious bright trail for the medium cyan background and a dirty trail behind the UFO cockpit in particular for the dark cyan background.

At 144Hz there is a significant decrease in the perceived blur that would be attributed to eye movement, with the object itself appearing sharper and narrower. There is quite a bold and extended trailing behind the objects as well, which is weakest using the ‘Strong’ setting and strongest using the ‘Off’ setting for ‘Overdrive’. There is also a bit of overshoot (a slightly dirty trail) when using the ‘Strong’ setting. The trailing is very pronounced with the dark background and here the overdrive doesn’t seem to make much difference for these transitions. The extent of trailing in all respective settings is greater than at 60Hz, which reflects the fact that the pixel responses simply can’t keep pace with the 6.94ms delay between frames here. The 160Hz setting doesn’t really make any significant changes here, which is perhaps unsurprising given that you’re only getting an extra 16Hz. The delay between frames is now cut to 6.25ms, so the pixel responsiveness certainly can’t ‘keep up’, so to speak.

From this analysis it would be fair to assume that setting the monitor to 160Hz and using the ‘Strong’ setting is optimal. In practice, though, there is obvious overshoot for some of the transitions that are not used here. The light background of this test (bottom row) actually highlights this to a degree as you can see from the image below. This can be seen at any refresh rate, although the image below was taken at 160Hz.

Overshoot with 'Strong' setting

In games this sort of overshoot and even more obvious examples are rather widespread and as such we found the ‘Medium’ setting to be optimal, despite some pixel transitions being noticeably slower. We therefore used ‘Medium’ at 160Hz for our testing. It’s clear from the analysis above that the monitor struggles with its pixel responsiveness and can’t really make full use of the high refresh rates. That was also the case with the Acer Z35, a comparison we will be drawing upon a bit in the subjective analysis below. As we will also explore you do still feel the advantage of the higher refresh rates, where frame rate is also high. Under similar conditions there is still a reduction in overall perceived blur due to a reduction in eye movement, as can be seen in the images above where the object itself is narrower and sharper at 144Hz and 160Hz compared to 60Hz. We will not be including a section on ‘overclocking’ this monitor; setting the refresh rate more than a couple of Hz above 160Hz causes the screen to lose signal with an ‘input not support’ message, regardless of timings.

Responsiveness in games and movies

On BF4 the monitor was able to bring a visual fluidity and level of felt responsiveness that is far beyond what any 60Hz LCD could deliver, especially where the frame rate kept pace with the 160Hz refresh rate. Interactions with the game world felt very smooth, with an excellent ‘connected feel’ that is much like you’d hope for from a high refresh rate model with low latency. The high frame and refresh rate combination also brought with it a significant reduction in perceived blur, which helped keep the game world more focused even during fast movements. There were definite weaknesses in pixel responsiveness on top of this, though, which gave rise to a ‘mask’ of blur on top. This was most noticeable where darker shades were involved, for example on some of the darker maps or for darker interior areas. Here there was an obvious ‘smeary’ quality to the trailing that was almost dizzying in places and had something of a ‘smoke-like’ quality to it.

The monitor did fare better where lighter shades were involved, which was most of the time on this title. But even then there was a degree of trailing and hence additional blur on top of what you’d ideally see from a high refresh rate monitor. We’d been quite used to the Dell S2716DG, used extensively both prior to reviewing this model and alongside it. And the AOC was noticeably weaker in terms of trailing. Perhaps a fairer comparison, though, would be with the Acer Z35. The AOC uses weaker pixel overdrive using its optimal ‘Medium’ setting compared to the Acer using its optimal setting. Even when comparing the Acer at 120Hz or 144Hz where the overdrive is a little more relaxed, there is a higher degree of overshoot on the Acer but also a bit less trailing for some of these common mid-tone transitions. There was actually no obvious overshoot on the AOC, which was nice to see, unless you used the ‘Strong’ overdrive setting. As we noted earlier this introduced obvious overshoot, although it also cut down on some of the stronger conventional trailing in places. We would have ideally liked to have seen a balance for pixel responsiveness on the AOC that is some way between the ‘Medium’ and ‘Strong’ setting.

Dirt Rally also benefited from the refresh rate in terms of the connected feel and reduction in perceived blur. The 160Hz refresh rate gave just a little benefit in this regard over 144Hz, but was certainly noticeably better than even the fastest 60Hz LCDs. There was again a fair degree of trailing in places for the ‘medium’ transitions that were common when racing during the daytime, even during fairly gentle cornering. This added a reasonably faint (but to sensitive users still noticeable) additional trail behind objects and hence an additional degree of blur. Where darker shades were involved, most notably when driving at night or in overcast conditions, there were some particularly leisurely pixel transitions that cropped up. This provided some smeary ‘smoke-like’ trails in places – although not measured with any sort of instrument other than our eyes, we’d say these could easily be over 10 times as slow as the specified 4ms grey to grey response time (i.e. 40ms+). There was again no obvious overshoot, just slight traces here and there that would easily escape notice.

We also observed the responsiveness of the monitor when viewing some Blu-rays. Obviously you aren’t interacting with these, so the low latency isn’t of any benefit. And the fluidity of the motion is also restricted by the ~24fps at which the films run. There was actually a slight reduction in ‘juddering’ if you run the monitor at 144Hz instead of 160Hz, too, as 24fps divides evenly into 144Hz but not 160Hz. For the most part things looked as they would even on models with technically much faster pixel responsiveness. There were some weaknesses here in there with some of the darker shades, providing brief after-images in places. These were faint, not particularly widespread and not something we found distracting, however.

FreeSync – the technology and activating it

AMD FreeSync is a variable refresh rate technology that is similar in its principles of operation to Nvidia G-SYNC. The refresh rate of the display is dynamically altered so that it matches, where possible, the frame rate of the content. Both of the articles linked to above explore why this is important, but on a basic level it prevents frame rate and refresh rate mismatches. Such mismatches cause stuttering (VSync on) or tearing and juddering (VSync off). Compare to running your games with VSync enabled, there is also a reduction in latency (not something we can accurately measure with our equipment, however).

The use of FreeSync requires a compatible AMD GPU and also a monitor that makes use of ‘VESA Adaptive-Sync’, which is a capability integrated into some DP 1.2a and HDMI 1.4a port controllers. As Adaptive-Sync is an optional extension you’ll sometimes see ports that support it labelled as ‘DP 1.2a+’ or ‘HDMI 1.4a+’. The existing scaler and electronics of a monitor is used rather than a proprietary ‘G-SYNC board’ (or similar bit of technology), with the key advantage of this being that it reduces the cost to the manufacturer and hence the user. Unsurprisingly, the number of monitors supporting this technology is far greater than those that support G-SYNC.

The AOC C3583FQ uses DP 1.2a with Adaptive-Sync support and therefore supports AMD FreeSync over DisplayPort. You need a compatible GPU (some current models are listed here – future AMD GPUs should also support this). Our test system uses the Club3D Radeon R9 290 royalAce, which is compatible with the technology. AMD’s recent drivers include Radeon Software Crimson, which makes activation of the technology very straightforward. It should be enabled automatically, but you can check its status by opening ‘AMD Radeon Settings’ and clicking on ‘Display’. You should then ensure that the first slider, ‘AMD FreeSync’, is set to ‘On’. If you hover over this, it will also report the variable refresh rate display supported by the display. Note that the image below is for a different monitor and is just used as an example here.



The AOC supports a variable refresh rate range of 45 – 160Hz. Outside of this range, the GPU respects your selection of ‘VSync on’ or ‘VSync off’ in the graphics driver. With ‘VSync on’ the frame rate will not be allowed to rise above 160fps – VSync will activate at this point, imposing the usual latency penalty associated with it. With ‘VSync off’ the frame rate is allowed to climb above the refresh rate ceiling of the monitor (>160fps), although the frame rate will obviously not be able to match it (160Hz). A fairly recent AMD feature called LFC (Low Framerate Control) is supported as well, which means that the monitors refresh rate will stick to multiples of the frame rate where it falls below the 45Hz (45fps) floor of operation. If the game was running at 30fps, for example, the refresh rate would be 60Hz to keep tearing and stuttering in check. This feature is used regardless of VSync setting.

VSync is configured in the ‘Gaming’ section of ‘Radeon Settings’, where it is referred to as ‘Wait for Vertical Refresh’. You can either configure this globally under ‘Global Settings’ or for each game individually. The default is ‘Off, unless application specifies’ which means that VSync will only be active if you enable it within the game itself, if there is such an option. Such an option does usually exist – it may be called ‘sync every frame’ or something along those lines rather than simply ‘VSync’. Most users will probably wish to enable VSync when using FreeSync to ensure that they don’t get any tearing. You’d therefore select either the third or final option in the list, shown in the image below.



Two final things to note related to the technology. Firstly, the application must be running in fullscreen mode, not a window (borderless or otherwise). Secondly, this monitor does not provide any indication that FreeSync is actually active. There are no changes to the power LED colour, no additional lights and nothing on the OSD saying when it’s using FreeSync and when it isn’t. You’ll therefore just have to assume that if you’ve set everything up correctly, as above, that it will be working. Hopefully the difference it makes to the experience, due to its effect on tearing and stuttering, will be quite obvious to many anyway.

FreeSync – the experience

BF4 is by no means as demanding as some modern game titles, but frame rate fluctuations are still something of an inevitability on most systems. Using the settings we’re happy to use this was certainly the case, with the frame rate generally averaging around 100fps but very rapidly fluctuating between around 80 – 120fps a lot of the time. Without FreeSync active this provides a jarring experience, with obvious tearing with VSync disabled and a ‘juddering’ effect which was quite unpleasant. With VSync enabled there was obvious stuttering, providing a significant loss of ‘flow’ to the onscreen action. With FreeSync enabled these fluctuations were far more palatable. The side-effect of dropping from the maximum frame rate that’s useful to the monitor (160fps) and around 100fps was that there was an increase in perceived blur and bit of an increase in felt-latency. However; the monitor still felt nice and responsive and there was a definite reduction in perceived blur compared to lower frame rates such as 60fps. The absence of tearing or stuttering from the traditional frame rate and frame rate mismatches was something that to many users would be quite game-changing. For us, although it’s the case of ‘the higher the better’ as far as frame rate goes, the experience was simply much more enjoyable with FreeSync enabled.

We also tested Tom Clancy’s The Division, which is quite a graphically demanding title. Using what we feel are fairly modest graphical settings, which allows the game to look pleasant without hammering the Radeon 290 too hard, the frame rate still remained relatively low given the optimal 160fps ceiling. Without FreeSync, stuttering (VSync on) or tearing and juddering (VSync off) was rife in these variable refresh rate environments. This title also seemed to have an issue with ‘Fullscreen’ not working when the game is first started up – it was obvious FreeSync wasn’t working when we entered the game. This was fixed by simply alt+tabbing out of the game and then going back in. Following this, FreeSync did its thing and made the experience flow much better without annoying interruptions from stuttering or tearing.

The frame rate was generally around 40 – 80fps on The Division, which certainly lacked the ‘connected feel’ and perceived blur reduction of higher frame rates even with FreeSync. Sometimes the frame rate dropped further to under the 45fps hardware floor for FreeSync on the monitor itself. AMD’s LFC technology, which we mentioned earlier, kicked in to keep tearing and stuttering at bay and certainly seemed to work as intended. Given that the frame rates are so low at this point, though, the movements within the game world were far from fluid. There was a sort of juddering (as if textures ‘vibrated’ when moving) that persisted simply due to the low frame rate rather than anything else. Preferable to the stuttering or tearing you’d get without FreeSync, but reinforcing the fact that low frame rates are always going to be low frame rates.

The 35″ 2560 x 1080 curved ‘UltraWide’ experience

This article focuses on the 2560 x 1080 resolution on a 29” monitor and the 21:9 aspect ratio more generally. We’ve also taken a look at the 3440 x 1440 resolution on a 34” screen in this article, revisiting the 21:9 experience. The AOC C3583FQ combines the 2560 x 1080 resolution with a 35” screen size. It also brings with it quite a steep curve, at 2000R. As we’ve already shared our thoughts on this in the same section of our Acer Z35 review, a model which uses the same panel, we will not be repeating this. Instead we’d encourage users to look at the relevant section of that review.

The analysis there not only looks at what the screen size, aspect ratio, resolution and curve bring to the table but also mentions interlaced interference patterns. These were present and manifested themselves in the same way on the AOC. There is also some talk of DSR (Dynamic Super Resolution), which Nvidia users can make use of. Obviously this model is more aimed at AMD GPU users, and their alternative technology (VSR – Virtual Super Resolution) does not currently support 21:9 resolutions. In-game implementations which achieve similar results, such as ‘resolution scale’ features, do still work. However; as noted in the Z35 review the advantages of using this sort of technology doesn’t really outweigh the disadvantages in our view. To round off this section we will simply leave some images of the C3583FQ in action – the images below are for illustrative purposes and are not a good representation of the actual image quality seen first-hand on the monitor. Any strange interference patterns on these images are moiré from the camera and were not observed on the monitor.

Conclusion

Having reviewed the Acer Z35 not long before the AOC C3583FQ, we had a fair idea of what to expect from the 35” screen with its steep curve and 2560 x 1080 resolution. In that respect, the concave and panoramic screen helped provide an engrossing gaming experience. This added to the sense of depth when gaming. The overall image quality was, unsurprisingly, quite similar to the Acer overall. Out of the box the monitor was far too bright and a touch on the warm side compared to the 6500K daylight white point target. It was quite well-balanced in terms of gamma, with a bit of deviation from the often desired ‘2.2’ curve but nothing troubling at all for entertainment or general usage. Colours were rich overall, although saturation levels did weaken a bit towards the edge and bottom of the screen. Another limitation came from the 2560 x 1080 resolution being spread across a 35” screen – a fairly low pixel density, in other words. The detail and clarity when gaming and the desktop real-estate was certainly limited by this – something some users will dislike but others will find perfectly satisfactory.

The real strength of VA panels, such as that used by the Z35, is contrast. In this respect the monitor did very well, exceeding the specified 2000:1 quite comfortably and coming closer to 3000:1 using a range of settings. The monitor was able to give dark scenes in games and movies a good atmosphere, whilst on the desktop text had a fairly bold and inky look. Bright elements in any application stood out nicely with darker surroundings as well. There was a degree of ‘black crush’ which hid some of the subtlest details from a normal viewing position, but no obtrusive immersion-breaking glow. Although not the lightest screen surface we’ve seen on an UltraWide monitor, the surface texture was still quite smooth and did not introduce obtrusive graininess to the image. The generous colour gamut, good gamma handling and overall panel characteristics also combined to give fairly rich colour output overall. There was some loss of saturation towards the side edges and further down the screen, though, which is expected given the panel type and size.

The responsiveness of the monitor was a mixed affair really. To its credit, the monitor did support 160Hz as promised and did so without introducing any artifacts that weren’t present at lower refresh rates. When coupled with the low input lag of the screen, games certainly had a nice ‘connected feel’ when played at high frame rates. FreeSync also worked as one would hope, putting an end to stuttering and tearing from refresh rate and frame rate mismatches. Pixel responsiveness was quite weak, overall, even using the optimal ‘Overdrive’ setting. There was obvious trailing in places as a result of this, even if some pixel transitions were snappy enough to make decent use of the high refresh rate. In this respect we found things somewhat slower than on the Acer Z35 (also using its optimal overdrive setting), although if a user finds one of these monitors troublesome for this reason then they’d likely find the other troublesome as well. Still, it’s worth remembering that this is subjective and regardless of the less than optimal pixel responsiveness, the monitor does still bring plenty of benefits to the user with its 160Hz refresh rate and FreeSync support. When coupled with a large and engrossing screen and a significantly lower price than the competition, this might be just the gaming experience some users are after.

The bottom line; a screen that delivers an engrossing and responsive-feeling gaming experience, but some definite weaknesses in pixel responsiveness.

 

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