Introduction

BenQ have been focusing their XL series of screens at gamers for many years now, and each time they refresh the models available they try to introduce something new and interesting to further enhance the gaming experience for their users. The XL series continues to be co-designed with professional Counter-Strike players and with the focus very much on offering all those extras and fancy features which offer the optimum LCD gaming experience. The XL models are still available in 24" and 27" sizes, and we have the latest version of the 27" model which is the XL2720Z with us for testing.

The series has come quite a long way since the first models back in 2011. We reviewed the XL2410T (24") model at that time which was BenQ's first 120Hz refresh rate compatible screen. About a year after they released the XL2420T model with some added features and extras, and since then the series has undergone several changes. This includes reducing the response time to 1ms G2G, upping the refresh rate from 120Hz to 144Hz and adding in flicker free backlight control (no PWM). The 24" XL2420Z and 27" XL2720Z are scheduled to be released in Europe around March time and represents their latest developments in the range. The aforementioned specs and features remain, but of particular interest here now are the additions of a Low Blue Light mode, designed to improve user comfort, and the addition of a Blur Reduction feature for gamers. This Blur Reduction feature is designed to be a development of the benefits discovered when using NVIDIA LightBoost strobed backlights but offered at an easy-to-use screen level.

BenQ's website states: "Built for competitive FPS game play, the XL2720Z takes the explosive thrills of fast-paced gaming to a 27� screen. The stunning monitor is equipped with the latest Motion Blur Reduction technology, Low Blue Light, Gaming-comfort Flicker-free, Gaming Refresh rate Optimization Management (GROM), and Display Pilot feature to deliver agile performance, viewing comfort and convenience all at once � for your victory and entertainment.".

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Specifications and Features

The following table gives detailed information about the specs of the screen:

The BenQ XL2720Z offers a full range of connectivity options. There are dual-link DVI, DisplayPort, D-sub (VGA) and 2x HDMI provided for video interfaces which is great to see. The digital interface is HDCP certified for encrypted content.

The screen comes packaged with a DVI and VGA video cable, but DisplayPort and HDMI are not provided The screen has an integrated power supply and so it only needs a standard kettle lead which is provided in the box. There is a built-in 3 port USB 2.0 hub as well on this model. There are no further extras such as integrated speakers, card readers or ambient light sensors although there is a headphone jack on the side if you are sending audio to the screen over HDMI.

Below is a summary of the features and connections of the screen:

OSD Menu

Above: views of OSD operational buttons on the bottom right hand edge of the screen

Pressing any of the five buttons pops up the quick access menu as shown above. This can be customised to provide you quick launch access to 3 settings you might regularly use. Here we have access to brightness, input and display mode (aspect ratio control). They can each be changed in the main OSD itself.

The main menu is split into 6 sections shown down the left hand side. The guidance logos on the right hand edge correspond to each of the 5 touch sensitive buttons and change depending on where you are in the menu, to show you how to control where you are.

The first section is the 'display' menu, greyed out here as they are controls for when using the analogue VGA input.

The second section is the 'picture' menu which contains most of the interesting options. There's the usual brightness and contrast controls here of course. There is also access to the Low Blue Light mode, Black eQualizer, new Blur Reduction feature and colour temperature modes within this first half of the menu. If you scroll down there are then further options presented.

The colour temperature modes are shown above with 3 preset levels, and a 'user mode' where you can adjust the RGB channels yourself for calibration.

The lower half of the 'picture' menu if you scroll down reveals a few other useful settings. There is the AMA (overdrive) control for response times, the Instant Mode for reduced input lag and also the gamma presets as shown above. It might have actually been easier to split some of the options (AMA, Instant Mode, Blur Reduction for instance) out into a separate 'gaming' section or something we felt, as there were a lot of options crammed into this one 'picture' section.

The third section is the 'picture advanced' menu. Here you can access the preset picture modes as shown above. Switching between them all is quite cumbersome actually as it takes about 2 seconds to change from one to another, and you have to scroll through each of them, with a 2 second change each time, to get down the list. Might have been better if you could scroll to your required setting and then activate it without needing to cycle through them all. This menu also has the dynamic contrast ratio control if you want to use it and the 'Display mode' menu for aspect ratio control.

The 'save settings' menu allows you to save your current OSD options to one of the 3 user customizable preset modes above which is useful.

The 'audio' menu controls the audio if you're using HDMI input and the headphone connection. You can also turn off the annoying OSD button beeps here with the 'buzzer' option.

The 'system' menu gives you various options relating to the OSD itself. You can define the 3 quick access buttons here as you wish, and also switch between inputs if need be.

There are a couple of other options at the bottom of the 'system' menu as shown above.

All in all the navigation was easy enough although sometimes you have to drill through several layers to get to where you want. If you exit the menu it doesn't remember where you last were so you have to go through it all again if you want to switch between settings often. Some sections felt a bit bloated but the touch-sensitive buttons work very well and were nice and responsive. Plenty of options to play with as well in the menu which is nice.

Power Consumption

In terms of power consumption the manufacturer lists 27W typical usage during operation and <0.5W in standby. We carried out our normal tests to establish its power consumption ourselves.

We tested this ourselves and found that out of the box the screen used 34.4W at the default 100% brightness setting. This was while the screen was set in its default FPS 1 preset mode. Once calibrated the screen reached 18.1W consumption, and in standby it used only 0.6W. We have plotted these results below compared with other screens we have tested. The XL2720Z shows a pretty typical usage for a W-LED backlit display:

Panel and Backlighting

Panel Part and Colour Depth

The BenQ XL2720Z utilises an AU Optronics M270HTN01.0 TN Film panel. The panel is capable of producing 16.7 million colours which is done with a 6-bit colour depth and an additional Frame Rate Control (FRC) stage (6-bit + FRC) as opposed to a true 8-bit panel. This is a measure commonly taken on TN Film panels, and the FRC algorithm is very well implemented to the point that an average user would be very hard pressed to tell any difference in practice compared with an 8-bit panel. The panel is confirmed when accessing the factory service menu (note: ignore the missing "0" in the panel part in the menu, that is an error, confirmed with BenQ):

Screen Coating

The screen coating on the XL2720Z is much like that featured on other TN Film screens. It is a medium Anti-glare (AG) offering, with moderate graininess common to most TN Film panels. It's not as clear as semi-glossy panels or fully glossy of course, but on the other hand it is not as grainy in appearance as older IPS panels which were often criticised for this. There is no sign of any cross-hatching type issues or other coating anomalies.

Backlight Type and Colour Gamut

The screen uses a White-LED (W-LED) backlight unit which has become very popular in today's market. This helps reduce power consumption compared with older CCFL backlight units and brings about some environmental benefits as well. The W-LED unit offers a standard colour gamut which is approximately equal to the sRGB colour space (equating to ~72% NTSC). Anyone wanting to work with wider colour spaces would need to consider wide gamut CCFL (WCG-CCFL) screens, or perhaps the new range of GB-r-LED displays available. If you want to read more about colour spaces and gamut then please have a read of our detailed article.
 

Backlight Dimming and Flicker

We tested the screen to establish the methods used to control backlight dimming. Our in depth article talks in more details about a common method used for this which is called Pulse Width Modulation (PWM). This in itself gives cause for concern to some users who have experienced eye strain, headaches and other symptoms as a result of the flickering backlight caused by this technology. We use a photosensor +  oscilloscope system to measure backlight dimming control with a high level of accuracy and ease. These tests allow us to establish

1) Whether PWM is being used to control the backlight
2) The frequency and other characteristics at which this operates, if it is used
3) Whether a flicker may be introduced or potentially noticeable at certain settings

If PWM is used for backlight dimming, the higher the frequency, the less likely you are to see artefacts and flicker. The duty cycle (the time for which the backlight is on) is also important and the shorter the duty cycle, the more potential there is that you may see flicker. The other factor which can influence flicker is the amplitude of the PWM, measuring the difference in brightness output between the 'on' and 'off' states. Please remember that not every user would notice a flicker from a backlight using PWM, but it is something to be wary of. It is also a hard thing to quantify as it is very subjective when talking about whether a user may or may not experience the side effects.

100%                                                50%                                                 0%

Above scale = 1 horizontal grid = 1ms

At all brightness settings a constant voltage is applied to the backlight and there is no need for Pulse Width Modulation (PWM) to be used. The XL2720Z is part of BenQ's ongoing flicker free initiative and we were very pleased to see it. A Direct Current (DC) method is used instead for backlight dimming here, so there is no chance of any perceived flicker or associated PWM side-effects at any brightness setting, all the way down to 0%.

For an up to date list of all flicker-free (PWM free) monitors please see our Flicker Free Monitor Database.

Contrast Stability and Brightness

We restored the screen to factory defaults, but for this test we changed out of the default 'FPS1' preset mode which is designed for gaming, and into the 'standard' preset mode instead.

The brightness control gave us a very good range of adjustment. At the top end the maximum luminance reached 282 cd/m² which was only just shy of the specified maximum brightness of 300 cd/m² from the manufacturer. There was a large 216 cd/m² adjustment range in total, and so at the minimum setting you could reach down to a luminance of 66 cd/m². This should be adequate for those wanting to work in darkened room conditions with low ambient light. A setting of ~23 in the OSD menu should return you a luminance of around 120 cd/m².

We have plotted the luminance trend on the graph above. The screen behaves as it should in this regard, with a reduction in the luminance output of the screen controlled by the reduction in the OSD brightness setting. This was pretty much a linear relationship. It should be noted that the brightness regulation is not controlled by Pulse Width Modulation and so offers a flicker free display.

The average contrast ratio of the screen was 993:1 and it remained stable across the brightness adjustment range as shown above.

Testing Methodology

An important thing to consider for most users is how a screen will perform out of the box and with some basic manual adjustments. Since most users won't have access to hardware colorimeter tools, it is important to understand how the screen is going to perform in terms of colour accuracy for the average user.

I restored my graphics card to default settings and disabled any previously active ICC profiles and gamma corrections. The screen was tested at default factory settings using the DVI interface, and analysed using an X-rite i1 Pro Spectrophotometer (not to be confused with the i1 Display Pro colorimeter) combined with LaCie's Blue Eye Pro software suite. An X-rite i1 Display Pro colorimeter was also used to verify the black point and contrast ratio since the i1 Pro spectrophotometer is less reliable at the darker end.

Targets for these tests are as follows:

• CIE Diagram - validates the colour space covered by the monitors backlighting in a 2D view, with the black triangle representing the displays gamut, and other reference colour spaces shown for comparison

• Gamma - we aim for 2.2 which is the default for computer monitors

• Colour temperature / white point - we aim for 6500k which is the temperature of daylight

• Luminance - we aim for 120 cd/m², which is the recommended luminance for LCD monitors in normal lighting conditions

• Black depth - we aim for as low as possible to maximise shadow detail and to offer us the best contrast ratio

• Contrast ratio - we aim for as high as possible. Any dynamic contrast ratio controls are turned off here if present

• dE average / maximum - as low as possible. If DeltaE >3, the color displayed is significantly different from the theoretical one, meaning that the difference will be perceptible to the viewer. If DeltaE <2, LaCie considers the calibration a success; there remains a slight difference, but it is barely undetectable. If DeltaE < 1, the color fidelity is excellent.

Default Performance and Setup

Default settings of the screen were as follows:

BenQ XL2720Z - Default Factory Settings, FPS1 Mode

  

 

Out of the box the screen looked reasonable to the naked eye. The screen was far too bright of course as it was set at its default 100% brightness setting. Some colours looked a little washed out and the screen felt perhaps a little too cool. Keep in mind the screen is shipped by default in the FPS1 preset mode, which is designed for gaming (as is the screen). We will test the default settings in the standard mode in a moment as well. We went ahead and measured the default state with the i1 Pro.

The CIE diagram on the left of the image confirms that the monitors colour gamut (black triangle) is approximately equal to the sRGB colour space, with some over-coverage evident in blue and green shades. Default gamma was recorded at 2.4 average, leaving it with an 8% deviance from the target of 2.2. This is a little higher than normal as a higher gamma is often favoured for gaming, and the screen is by default in the gamers FPS1 preset mode. White point was measured at 7324k leaving it with a 13% deviance from our target of 6500k, being a bit too cool. Note that we are using a spectrophotometer to make these measurements which is not sensitive to the wide gamut backlight as some colorimeter devices can be. When using a standard gamut colorimeter not designed to work with modern backlighting units like W-LED, WCG-CCFL and GB-r-LED there can be a typical deviance of 300 - 600k in the white point measurement which is why some sources may refer to a different white point in this test incorrectly.

Luminance was recorded at a bright 249 cd/m² which is too high for prolonged general use. The screen was set at a default 100% brightness in the OSD menu but that is easy to change of course to reach a more comfortable setting. The black depth was 0.30 cd/m² at this default brightness setting, giving us a pretty good (for a TN Film panel) static contrast ratio of 831:1. This was a little lower than we'd seen in our previous section, where we'd looked at the brightness range and contrast in the 'standard' preset mode. Colour accuracy was poor out of the box with a default dE average of 4.9, and maximum of 10.9. This is probably to be expected though as again we are in the FPS 1 gaming preset mode, where accuracy is sacrificed for bright and vivid colours for games. Testing the screen with various gradients showed smooth transitions with no sign of any banding thankfully. There was some slight gradation evident in darker tones as you will see from most monitors and if you looked very closely you could pick out some twinkling from the Frame Rate Control. Not something you'd see in normal use though at all.

Overall this default setup is probably pretty decent for gaming requirements, but it's hard to comment on it really when considering more general uses where we prefer a higher level of accuracy. We will test the screen again at default settings, this time in the 'standard' preset mode instead.

BenQ XL2720Z - Default Factory Settings, Standard Mode

 

We then switched to the 'standard' preset mode to establish the default performance in a more "normal use" mode. The set up here was better than the FPS1 mode, as you might expect, for day to day uses. Gamma was now closer to the 2.2 target with only a 1% deviance. We had stuck with the gamma mode 3 in the OSD menu here by the way. White point was also closer to the 6500k target, measured at 6769k now and only 4% out, and this was set in the 'normal' colour temperature mode in the OSD menu. There is also a user mode to allow you to tweak the RGB channels which will be useful for calibration in a moment. Colour accuracy was a bit better too with average dE now 3.6. Still not particularly accurate of course, but a better balance now in the 'standard' mode, which you could also tell with the naked eye. The screen doesn't carry any particular factory calibration checks like some higher end models as it's more aimed at the gaming market. The contrast ratio was a little higher in this mode too at 972:1 which was pleasing and an excellent result for a TN Film panel.

Calibration

We used the X-rite i1 Pro spectrophotometer combined with the LaCie Blue Eye Pro software package to achieve these results and reports. An X-rite i1 Display Pro colorimeter was used to validate the black depth and contrast ratios due to lower end limitations of the i1 Pro device.

BenQ XL2720Z - Calibrated Settings

   

We first of all reverted to the 'standard' preset mode in the OSD menu to allow us access to the individual RGB channels and to also give us a more accurate starting point than the gamer FPS modes. We also switched to the 'user' colour temperature mode which would give us access to the individual RGB channels. Adjustments were made during the process to the RGB channels as shown in the table above as well as the brightness control. This allowed us to obtain an optimum hardware starting point and setup before software level changes would be made at the graphics card level. We left the  LaCie software to calibrate to "max" brightness which would just retain the luminance of whatever brightness we'd set the screen to, and would not in any way try and alter the luminance at the graphics card level, which can reduce contrast ratio. These adjustments before profiling the screen would help preserve tonal values and limit banding issues. After this we let the software carry out the LUT adjustments and create an ICC profile.

Average gamma had been corrected to 2.2 average, correcting the default 1% deviance we'd found out of the box in the 'standard' preset which was good, and certainly improving on the 8% deviance we'd seen in the default 'FPS1' mode. The white point was also corrected to 6505k, correcting the slightly cool setting we had observed before in this preset (4% deviance). Luminance had also been improved thanks to the adjustment to the brightness control and was now being measured at 119 cd/m². This left us a black depth of 0.13 cd/m² and retained an excellent (for a TN Film panel) static contrast ratio of 950:1. Colour accuracy had been corrected nicely, with dE average of 0.5 and maximum of 1.2. LaCie would consider colour fidelity to be excellent. We measured a 105% sRGB gamut coverage (rendering = none (or Print Test)) using the Gamutvision tool and our resulting profile.

Testing the screen with various colour gradients showed mostly smooth transitions. There was some slight gradation in darker tones but no banding introduced due to the adjustments to the graphics card LUT from the profilation of the screen which was pleasing. You can use our settings and try our calibrated ICC profile if you wish, which are available in our ICC profile database. Keep in mind that results will vary from one screen to another and from one computer / graphics card to another.

Calibration Performance Comparisons

The comparisons made in this section try to give you a better view of how each screen performs, particularly out of the box which is what is going to matter to most consumers. When comparing the default factory settings for each monitor it is important to take into account several measurement areas - gamma, white point and colour accuracy. There's no point having a low dE colour accuracy figure if the gamma curve is way off for instance. A good factory calibration requires all 3 to be well set up. We have deliberately not included luminance in this comparison since this is normally far too high by default on every screen. However, that is very easily controlled through the brightness setting (on most screens) and should not impact the other areas being measured anyway. It is easy enough to obtain a suitable luminance for your working conditions and individual preferences, but a reliable factory setup in gamma, white point and colour accuracy is important and not as easy to change accurately without a calibration tool.

From these comparisons we can also compare the calibrated colour accuracy, black depth and contrast ratio. After a calibration the gamma, white point and luminance should all be at their desired targets.

Default setup of the screen was pretty poor overall, but before you start worrying too much, this is while the screen is set in its default FPS 1 preset mode. This mode is designed for gamers, where "accuracy" is sacrificed somewhat for a higher gamma, and more bright and vivid colours. The screen is shipped in this mode since it's a gamers screen and it makes sense to do so. However, for day to day use the accuracy is not great. You have a default gamma of 2.4 which leaves an 8% deviance from the 2.2 target overall. The white point is also a little too cool at 7324k, leaving it 13% out. Colour accuracy is also poor with an average dE of 4.9 recorded. It is easy enough to improve these measurements quite noticeably by simply switching to the 'standard' preset mode instead, more designed for day to day usage. In doing so you improve the gamma to within 1% of the target, white point within 4% (still slightly too cool) and improve colour accuracy a bit to give you average dE of 3.6. So while the "default" out of the box performance isn't great for normal uses, it's easy to change to another preset mode where it is noticeably better.

The panel did well in terms of black depth and contrast ratio for a TN Film matrix, with a calibrated contrast ratio of 950:1 measured. This couldn't compete with some of the AMVA based screens we've tested which could reach up to 2000:1 static contrast ratios (BenQ GW2760HS) easily, or the MVA based Eizo FG2421 which reached up to 4845:1. The XL2720Z offered a higher contrast ratio than some other TN Film based models we've tested here like the Asus VG278HE (799:1), BenQ XL2420T (839:1), Iiyama G2773HS (788:1) and ViewSonic VX2739WM (807:1). 

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Low Blue Light

The XL2720Z features a new settings which BenQ have introduced as part of their "EyeCare" initiative. As well as the move to flicker free backlights (without using PWM), this Low Blue Light (LBL) mode is designed to reduce the blue spectrum light emitted by the W-LED backlight unit, and can to some people be a critical cause of eye damage, eyestrain, headaches and sleeping disorders. Now with the offering of various adjustable low blue light levels, gamers can better protect their eyes. So there would be no need for yellow tinted eyeglasses for additional eye protection, and game play can be clear, comfortable and hassle-free! The LBL setting is designed to be easy to access and use for all users, even those without calibration devices.

We wanted to test the impact of this Low Blue Light setting ourselves. It's available in the 'picture' section of the OSD menu with a setting from 0 - 10 available. First of all we set it to 0 (off) in the menu and calibrated the screen as we would normally, and as described in our calibration section of this review. We then measured the white point / colour temperature of the screen and the spectral distribution at each of the settings, reaching up to the maximum setting of 10.

Spectral Distribution = calibrated to 6500k, then LBL setting 0

With Low Blue Light mode set to 0 (off) we achieved a white point of 6515k, being very close to the calibrated target. If we look at the spectral distribution curve, as measured with our i1 Pro Spectrophotometer you can see that in the blue light there is a peak. This is what the Low Blue Light mode is designed to reduce, as it is this imbalance in the spectral distribution which can, in some people lead to eye issues.

We kept the exact same monitor and ICC profile settings from our calibrated state, and simply changed the Low Blue Light setting option. we measured the white point / colour temperature at each setting and recorded them in the table above. As you can see, as you increase the LBL setting, the white point gets progressively warmer. Logical of course since you are trying to reduce the blue spectrum.

Spectral Distribution = calibrated to 6500k, then LBL setting 5

Spectral Distribution = calibrated to 6500k, then LBL setting 10

If we compare the spectral distribution curves at LBL settings of 5 and 10, you can see that the blue peak is being reduced as intended which is pleasing. However, you are left with a warmer colour temperature. The setting is changing more elements of the setup than just the white point though from our discussions with BenQ technicians.

We then left the LBL setting at a maximum of 10, and re-calibrated the display to achieve a target 6500k white point. To do this, you will have to alter the RGB channels again, and this time we had RGB at 90, 89, 99 respectively. We let the LaCie software carry out the normal calibration process and all targets were met nicely as before. We then re-measured the spectral distribution curve, with LBL at maximum 10, but after having been recalibrated to achieve a 6500k white point:

Spectral Distribution = LBL setting 10, then calibrated to 6500k after

The results were quite good actually. We had a lower blue peak than we had with LBL set to off (calibrated to 6500k). It was not as low as it had reached before, when we had calibrated first to 6500k before changing the LBL setting. You do seem to be able to combine the two though, having the LBL setting enabled, but then carrying out a calibration to achieve a white point nearer to 6500k again. This might be a useful setting to play with if users have sensitive eyes and it's nice to see BenQ continue to focus their efforts on user comfort.

Viewing Angles

Above: Viewing angles shown from front and side, and  from above and below. Click for larger image

Viewing angles of the XL2720Z were as you might expect from a TN Film panel. Unfortunately this panel technology is inherently poor in this field, and so viewing angles are far more restrictive than other competing technologies like IPS, PLS and VA. Although the manufacturer will quote a viewing angle of 170 / 160 (a classic indication that a TN Film panel is being used by the way if in doubt), in practice there are some obvious contrast and colour tone shifts horizontally, and especially vertically.

As you move your head from side to side in a horizontal plane, there is a contrast shift and the image becomes darker and introduces a slight green hue. As you move to a wider angle the image can become more washed out as well. Vertically the fields of view are more restrictive still. From above the image becomes pale and washed out, while from below there is a characteristic TN Film darkening of the image. Unfortunately vertically the viewing angles will introduce noticeable shifts in the contrast and colour tone of the image which mean that for any colour critical work it is not really very well suited. TN Film panels have long suffered from these restrictive viewing angles due to the nature of their pixel structure. They are still fine for a single user for general use and certainly the TN Film panels offer their advantages when it comes to pixel response times and gaming. If however, you were hoping to do any colour critical or photography work you may find these shifts in the appearance of the image difficult. An IPS panel would probably be a wiser choice if you were looking for a screen with much wider viewing angles but having said that you are probably mainly interested in gaming if you are considering this screen.

Above: View of an all black screen from the side. Click for larger version

On a black image there is a pale grey tint introduced to the image when viewed from a wide angle. This isn't too severe and shouldn't present any real problems in practice. Certainly not the obvious white glow you get from most modern IPS panels in similar situations.

Panel Uniformity

We wanted to test here how uniform the brightness and colour temperature was across the screen, as well as identify any leakage from the backlight in dark lighting conditions. Measurements of the luminance and colour temperature were taken at 35 points across the panel on a pure white background. The measurements for luminance were taken using BasICColor's calibration software package, combined with an X-rite i1 Display Pro colorimeter with a central point on the screen calibrated to 120 cd/m². Measurements for colour temperature (white point) were taken using BasICColor software and the i1 Pro spectrophotometer which can more accurately measure the white point of different backlighting technologies. The below uniformity diagram shows the difference, as a percentage, between the measurement recorded at each point on the screen, as compared with the central reference point.

It is worth noting that panel uniformity can vary from one screen to another, and can depend on manufacturing lines, screen transport and other local factors. This is only a guide of the uniformity of the sample screen we have for review.
 

Uniformity of Luminance

The luminance uniformity of the screen was good overall. The lower left hand and upper middle edges showed the most deviance from a central point of 120 cd/m², dropping down to 104 cd/m² in the most extreme cases (-15.38%). The central and right hand regions were more uniform, staying within a 10% deviance on the most part. Around 83% of the screen was within a 10% deviance of the target which was a pleasing result.
 

Backlight Leakage

Above: All black screen in a darkened room. Click for larger version

As usual we also tested the screen with an all black image and in a darkened room. A camera was used to capture the result. There was no obvious backlight bleeding detectable to the naked eye. The camera picked up a lighter region of glow along the bottom edge but nothing too severe at all.

General and Office Applications

The BenQ XL2720Z sticks with a 1920 x 1080 resolution across its 16:9 aspect panel, contrary to a lot of super high resolution 27" models in the market. While this of course has some cost saving advantages, and is perfectly suitable for multimedia use, it is not as good for general day to day office work. This lower resolution on such a large screen means there is a 0.311mm pixel pitch and the text appears large as a result. This might be good for those with any kind of eye sight issues, and for those who prefer a larger text size for a lot of web and text based work. However, you need to consider that this same 1920 x 1080 resolution can be found on small screens as well, including 21.5" diagonal models. On screens that size the resolution is arguably a little too high and text is a little too small, but on a 27" diagonal sized screen we personally think it is a bit too low. The screen is certainly comfortable for a lot of text reading, but it just doesn't look quite as sharp and crisp as a higher resolution equivalent. You do also really miss the desktop real-estate when coming from a 2560 x 1440 screen to this.

The moderate AG coating of the TN Film panel is not an issue and doesn't produce any obvious graininess to the image. The limited viewing angles of the TN Film panel technology are perhaps the screens main weakness, meaning that you will notice colour and contrast shifts if you deviate from a head on view of the screen. This may be problematic if you are doing any colour work, or trying to view content from different positions. The default setup of the screen in the default FPS1 mode was pretty poor for office and general work. Switching to the 'standard' preset mode yielded a better result and provided a reasonable setup for those without a colorimeter. It didn't offer the levels of accuracy you'd see from some higher end screens, or those carrying a dedicated factory calibration mode, but this screen isn't really aimed at that audience.

The contrast ratio was excellent for a TN Film panel at 950:1 after calibration which was pleasing. The brightness range of the screen was also very good, with the ability to offer a luminance between approximately 282 and 66 cd/m². This should mean the screen is perfectly useable in a wide variety of ambient light conditions, including darkened rooms. A setting of ~23 in the OSD brightness control should return you a luminance close to 120 cd/m². On another positive note, the backlight regulation is controlled without using Pulse-Width modulation (PWM) and so the screen is flicker-free. Those who suffer from eye fatigue or headaches associated with flickering backlights don't need to worry here. On another note, make sure you have the Blur Reduction feature disabled in normal uses as otherwise that will introduce a flicker.

There was no audible noise or buzzing from the screen, even when specifically looking for it using test images with a large amount of text at once. The screen also remains cool even during prolonged use. There is no specific 'text' preset mode available from the menu or anything so you will need to set up one of the other modes to your liking. You have the option to save three user defined preset modes as well in the OSD menu, which means you can easily set something up to your liking. The Low Blue Light mode might well be useful for office work, and to provide more eye comfort to the user. The DVI connection provided a slightly sharper and crisper image than the VGA connection, although the latter was still very good really.

The screen offers 3x USB 2.0 ports which can be useful, although a lot of modern screens are now offering USB 3.0 instead. Might have been nice to keep this up to date with them perhaps. Two are available on the left hand edge of the screen for easy access which was nice, along with a headphone jack if needed.  There are no further extras like ambient light sensors or card readers which can be useful in office environments. There was a great range of easy to use ergonomic adjustments available from the stand allowing you to obtain a comfortable position for a wide variety of angles. The VESA mounting support may also be useful to some people as well, and the carry handle on the back of the stand is also a nice feature for those who need to take the screen to different locations.

 
Above: photo of text at 1920 x 1080 (top) and 1600 x 900 (bottom)

The screen is designed to run at its native resolution of 1920 x 1080 and at a 60Hz recommended refresh rate. However, if you want you are able to run the screen outside of this resolution. We tested the screen at a lower 1600 x 900 resolution to see how the screen handles the interpolation of the resolution, while maintaining the same aspect ratio of 16:9. At native resolution the text was sharp as you can see from the top photograph. When you switch to a lower resolution the text is larger of course but still clear enough with only low amounts of overlap between pixels. The screen seems to interpolate the image well although you of course lose a lot of desktop real-estate running at a lower resolution.

Responsiveness and Gaming

The XL2720Z is rated by BenQ as having an 1 ms G2G response time and the panel uses overdrive / response time compensation (RTC) technology to boost pixel transitions across grey to grey changes. There is control over the overdrive impulse within the OSD menu using the AMA (Advanced Motion Accelerator) option, giving the user some control over the aggressiveness of the overdrive. The part being used is the AU Optronics M270HTN01.0 TN Film panel. Have a read about response time in our specs section if you need additional information about this measurement.

We will first test the screen using our thorough response time testing method. This uses an oscilloscope and photosensor to measure the pixel response times across a series of 20 different transitions, in the full range from 0 (black) to 255 (white). This will give us a realistic view of how the monitor performs in real life, as opposed to being reliant only on a manufacturers spec. We can work out the response times for changing between many different shades, calculate the maximum, minimum and average grey to grey (G2G) response times, and provide an evaluation of any overshoot present on the monitor.

We use an ETC M526 oscilloscope for these measurements along with a custom photosensor device. Have a read of our response time measurement article for a full explanation of the testing methodology and reported data.

AMA Comparison

We will first of all look at the differences in response time and overshoot under the different AMA (overdrive) settings. The AMA setting is accessed via the 'picture' section of the OSD menu as shown above.

AMA Off at 60Hz

First of all we tested the screen with the AMA turned to 'off' and at a refresh rate of 60Hz. This should turn off the overdrive impulse in theory, which should leave us with slower overall pixel response times, but hopefully no noticeable overshoot problems as a result. With AMA off the response times were very variable and it's perhaps best to look at some of the graphs produced to explain what is happening. Remember, this is at a 60Hz refresh rate initially.

Transition: 0-50-0 (scale = 20ms) @ 60Hz

For the transition shown above you can see that the rise time from 0-50 is very slow, measured at 18.3ms in our table above. That is because there seems to be a step in the brightness curve as it tries to reach the desired brightness level (50). As a reminder, the lower flat line represents the darker shade of the transitions (0), and the upper flat(ish) line represents the lighter shade of the transition (50). It seems that the brightness only reaches part of the way towards the required level, in fact only reaching 78% of the target when it reaches the "step". It takes around 7ms to reach that point from the starting lower flat line (0). It then stays at that brightness for about 9.7ms before it then increases again, to reach up to the desired brightness level (50).

Transition: 0-50-0 (scale = 20ms) @ 60Hz

If you look at that time it takes for the step to complete, before the brightness starts to increase again up towards the desired level, it is 16.667ms, which equates to 1 frame at 60Hz refresh rate. So it seems that the pixel is driven to around 78% of its desired brightness with 1 frame, and then it takes part of a second frame to reach up to be within the threshold for a response time measurement - that being when the brightness reaches 90% of its target. As a result we are left with a very slow overall response time of 18.3ms to reach within 90% of the required brightness (the rise time). This same pattern can be seen on several of the transitions recorded in the table above, where a "step" occurs in the graph, and it takes 1 frame before the brightness is then increased again towards its desired level.

On the other hand, the fall time from 50-0 is very fast indeed, measuring only 1.4ms. There is some 'stepping' of the brightness curve but it's very close to the desired brightness so does not impact the response time measurement, and it reaches the required required brightness very quickly.

Transition: 150-255-150 (scale = 20ms) @ 60Hz

If you then look at the above transition from 150 (light grey) to 255 (white) at 60Hz refresh rate the pixel transitions are different. The rise time is faster and there is a much less pronounced step in the brightness curve, and in fact this only happens when it is much nearer to the required brightness anyway. Here it is measured at a much more reasonable 8.8ms. However, the fall time is now very slow, measured at 19.6ms.

It is all these variations which lead to the slow response times for many transitions when AMA is turned off and you are using a 60Hz refresh rate. This left us with an average G2G response time of 11.8ms which was slow for a TN Film panel like this. The fastest transitions did reach down to around 1.4ms at best which was good, but the slower changes up to around 21ms were an issue. On the plus side, there was no overshoot evident at all with AMA turned off, as you might hope.

AMA Off at 144Hz

You can reduce the response times though because of the way this stepping of the brightness curve is occurring. The way the pixels behave remains unchanged, but if you increase the refresh rate you can push more frames to the screen. The step in the brightness curve still occurs, and it still only increases the brightness again towards the desired level at the end of 1 frame. If you're running at 120Hz for example, 1 frame now only last 8.33ms (half the time of 60hz), so overall the time it takes to reach 90% of the desired brightness is reduced. If you push the refresh rate up to the maximum supported 144Hz 1 frame now lasts 6.94ms, so again the response time is improved. The step is still there on certain transitions as it was before, but the frame lasts a shorter amount of time so it is quicker to begin the ascent up to the desired brightness after the step has occurred.

As you can see, at 144Hz the average G2G response time has improved now to 7.5ms with AMA off. Rise times are slower than the fall times. As before, there is no overshoot as the AMA function is off.

Transition: 0-50-0 (scale = 20ms) @ 144Hz

The graph for the 0-50-0 transition above shows that at 144Hz, the "stepping" in the brightness curve still occurs, but lasts a much shorter time since we are now running the screen at 144Hz instead of 60Hz. This reduces the response time measurement for the 0-50 transition from 18.3ms to 8.4ms.

AMA 'High'

With AMA turned to the middle setting of 'High' there was an obvious improvement in the response times. You will see from the table above that we now had an average G2G response time of only 3.4ms which was excellent, and a big improvement to what we'd seen before with AMA off. The stepping of the brightness curve had stopped and transitions were now very fast, both for rise times and for fall times. The refresh rate doesn't have an impact on the response times here and it is the same at 60, 120 and 144Hz.

Transition: 0-50-0 (scale = 20ms) @ 60Hz

If we look at some of the graphs though and the results in the table you can see that the improved response times aren't without their side-effects. There is some significant overshoot introduced, particularly on the transitions which were previously very slow, but had now been sped up to around 2 - 5ms. For instance the graph above shows the previously very slow 0-50 transition, which was measured at 18.3ms when AMA was off. Here it was much faster at 2.4ms, but introduced a pretty significant 32.7% overshoot where the brightness exceeds the desired level at the top of the curve.

Note that the graph above is when running at 60Hz refresh rate. We will look at the impact of refresh rate setting on the overshoot in a moment.

Transition: 150-255-150 (scale = 20ms) @ 60Hz

There was also some overshoot on the fall times where again the pixel transitions had been sped up. The fall time on the above from 255-150 was previously slow at 19.6ms, now sped up to only 3.9ms. A large 27.5% overshoot was introduced as a result though for the trouble.

So the AMA High setting did a really good job of sorting out the slow response times we'd seen when the setting was off. The actual pixel transitions were much faster overall now. However the overshoot introduced as a result was unfortunate and at a reasonably high level as well in places.
 

AMA 'Premium'

With AMA now turned up to the maximum 'Premium' setting you can see that the overall response times remained very similar to the 'High' setting. We maintained an average 3.4ms G2G response time here and overall the measurements were very similar to before when it came to pixel transition times. However, the overshoot which we had seen in the 'High' AMA mode were now even more problematic. The overshoot affected the same transitions as before, namely those which had previously been very slow when AMA was off. It was now an even higher degree than before though. For example the overshoot from 0-50 had increased from 32.7% (AMA High) to 58.3% (AMA Premium).

Since there was no benefit to the response times, we wouldn't recommend using this AMA Premium mode, as the overshoot is just increased with no benefit to the user. AMA High seemed to be the best option available from the screen, overcoming the slow response times of AMA Off, but without introducing the very high overshoot of AMA Premium.

Transition: 0-50-0 (scale = 20ms) @ 60Hz

An example shown above demonstrates the fast rise and fall times, but the high overshoot on the rise time (58.3%).

If we also carry out some subjective assessment of the screen during gaming and with the use of the PixPerAn moving car tests, we can also see the differences between each AMA mode easily enough with the naked eye. These images taken of the moving car test taken at 144Hz refresh rate, supporting what we've measured with the oscilloscope as well. With AMA off there is a moderate blur to the moving image. This is less evident when the screen is running at 144Hz refresh rate (shown here) than when running at 60Hz as well, and you of course then also benefit from a higher frame rate and smoother movement. There are no noticeable overshoot artefacts with AMA set to off either. When you switch AMA to 'High' the blurring is eliminated greatly, and you see a sharper moving image as a result. There is some dark trailing shown in the sample colour transitions used in PixPerAn which you can see in the images. It doesn't affect every colour transition  as we've already measured in this section and in gaming it isn't overly problematic. It is there in certain situations but the improvement in response times and reduction in blur is worth the sacrifice we feel. If you then bump the AMA setting up to 'Premium; there is not really any noticeable improvement to the movement on the screen, but the overshoot becomes far more noticeable. The dark trails become darker and more pronounced and there is also some additional pale overshoot introduced behind the car. AMA 'High' seems to be the best balance we felt in practice as well as based on our oscilloscope tests.
 

Impact of Refresh Rate on Overshoot

60Hz                                                                                100Hz

120Hz                                                                                144Hz

All graphs are for the transition: 0-50-0 (scale = 20ms)

In the above AMA comparison section we measured the pixel response time and overshoot while the screen was set at a normal 60Hz refresh rate. The higher refresh rates bring about improved frame rates, smoother movement and improved gaming experience overall. One area which is also positively impacted by the higher refresh rates is the overshoot.

If you compare the graphs for the same 0-50-0 transition with AMA set to Premium at each refresh rate you can see that the level of overshoot remains the same when considering how far the brightness overshoots the desired level. As a reminder, the starting grey shade (0 in this example) is represented by the lower flat line on the graph. The desired brightness for the second grey shade (50) is represented by the upper flat line on the graph. The time taken to switch between these two states (0-50-0) is the response time. The peak on each graph where the brightness / grey shade "overshoots" the desired shade is the overshoot caused by the response time compensation (AMA feature). In each case the overshoot is measured as a % of how far above the desired brightness (the upper flat line) the peak extends. No matter what the refresh rate, the overshoot percentage is always the same, and in this example where we have the AMA setting at 'Premium', the overshoot is ~58%.

What is of interest though is that the time for which the higher overshoot brightness is present before it drops back to the desired brightness level gets progressively shorter as you increase the refresh rate. This is a result of the refresh rate which is sending more frames to the screen and so can help reduce some of the overshoot appearance for the user. The overshoot level is still the same, but the unwanted brightness level doesn't linger for as long. As a result, the overshoot in practice becomes a little less pronounced as you increase the refresh rate, although it is still there and can still be seen, especially with AMA set to the maximum 'Premium' setting. An AMA setting of 'High', and a refresh rate of 144Hz provides the best moving image quality.

More Detailed Measurements - AMA High

Having established that the AMA High setting returned the optimum results for pixel responsiveness, we went ahead and measured a wider set of transitions for completeness. The average G2G response time was measured at a very good 3.4ms. The lowest response time we saw was 1.4 and the highest was 7.0 ms. Rise times (changes from darker to lighter shades) were a little slower on average at 5.0ms, compared with fall times (changes from lighter to darker shades) at 2.7ms average. All in all, a very good performance as you would hope for from a fast TN Film panel.

If we evaluate the RTC overshoot you can see that on the whole it was at a moderate level, but not too bad, even with AMA switched up to High. We know that pushing AMA up to Premium seems to bring no real benefits in terms of pixel response times, but produces a more noticeable and severe overshoot. Here, there were a hand full of transitions which had a high level of overshoot, most noticeably when changing from black (0) to darker/medium grey shades. A few changes from white (255) to medium grey shades also showed some high overshoot. All in all though, it wasn't too severe and we felt that the trade-off to get the fast pixel response times which AMA High provided was worth it.

Display Comparisons

As we begin to measure more screens with the oscilloscope system we can begin to plot them on a graph like the above for easy comparison. This shows you the lowest, average and highest G2G response time measurement for each screen. There is also a traffic light style circle mark to indicate the RTC overshoot error for each screen, as the response time figure alone doesn't tell the whole story.

As you can see, the XL2720Z performed very well in this comparison thanks to its fast TN Film panel. It is a little faster at 3.4ms G2G average than the other TN Film panel we've tested here, the Asus VG278HE (4.1ms) although the BenQ did show a slightly more pronounced overshoot. The IPS based panels can't keep up with these response times and seem to reach around 9ms average at best, without introducing a large amount of overshoot.

The screen was also tested using the chase test in PixPerAn for the following display comparisons. As a reminder, a series of pictures are taken on the highest shutter speed and compared, with the best case example shown on the left, and worst case example on the right. This should only be used as a rough guide to comparative responsiveness but is handy for a comparison between different screens and technologies as well as a means to compare those screens we tested before the introduction of our oscilloscope method.

27" 1ms G2G AU Optronics TN Film + 144Hz (AMA = High)

In practice the BenQ XL2720Z showed very low levels of blur when set at the optimum AMA setting of 'High' and with the refresh  rate set at the maximum 144Hz. There was no obvious blurring behind the moving car although some dark overshoot was introduced in places due to the overdrive impulse.

27" 1ms G2G AU Optronics TN Film + 144Hz (AMA = High)

27" 2ms G2G Chi Mei Innolux TN Film +144Hz (Trace Free = 60)

24" 2ms G2G AU Optronics TN Film + 120Hz (AMA = On)

27" 1ms G2G Chi Mei Innolux TN Film + 120Hz (Over Drive = 0)

Firstly it is interesting to compare the XL2720Z to some of the other 120Hz+ compatible TN Film gaming displays we have tested. All of these models offered very low levels of motion blur in practice thanks to their fast response times and high refresh rates. The Asus VG278HE was very comparable in practice although showed a less noticeable overshoot in these specific tests than the BenQ. We know from our detailed oscilloscope measurements of that screen that there is some overshoot in certain situations, but it's not picked up in these PixPerAn tests here. That's why it's good to carry out both tests where possible. The BenQ XL2420T 24" screen is quite comparable to the XL2720Z we felt in practice, which isn't a bad thing as that is a well-established gaming screen in the market. Obviously the XL2720Z is 3 inches bigger though.

27" 1ms G2G AU Optronics TN Film + 144Hz (AMA = High)

23.5" 4ms G2G Sharp MVA + 120Hz

It's also interesting to compare the XL2720Z with the recently tested Eizo Foris FG2421 gaming monitor. The Eizo features a fast MVA panel from Sharp, combined with the first 120Hz refresh rate native support outside of TN Film matrices. In practice, the BenQ feels a little faster in movement, providing a slightly sharper moving image. It also carries the additional benefit of a higher frame rate support of 144Hz, as compared with 120Hz on the Eizo. The Eizo however does remain free from overshoot problems and so from that perspective it can appear a little nicer in certain situations when viewing dynamic content.

Before we get into the other display comparisons below it's important to realise that the additional smoothness and increased frame rate which 120Hz+ offers as compared with 60Hz cannot be picked by these camera tests. These gaming screens we've looked at offer a big advantage in real performance over the 60Hz displays shown below, and for gaming they have an obvious benefit. Don't forget also that most of them support NVIDIA 3D Vision as well for stereoscopic 3D content, or the additional third party use of the LightBoost backlight system for motion blur reduction. Again you can't demonstrate the benefits of this blur reduction using a simple photo method, but it makes a noticeable and marked improvement to the smoothness and experience in games.

27" 1ms G2G AU Optronics TN Film + 144Hz (AMA = High)

27" 8ms G2G Samsung AD-PLS

23.8" 8ms G2G LG.Display AH-IPS

24" 7ms G2G LG.Display AH-IPS

We have provided a comparison of the XL2720Z against a few popular Dell screens. The P2714H and P2414H had impressed us considering their IPS/PLS panel technologies, and represented about the best you can get from a modern IPS panel at the moment for response times, without introducing any overshoot problems. In practice they couldn't keep up with the BenQ and showed a more pronounced blur to the moving image. The Dell S2740L showed low levels of motion blur and the moving image was a little sharper than on the P series screens here we felt. However, a noticeable dark overshoot was introduced, caused by an overly aggressive overdrive impulse. This is the problem when trying to push response times of IPS matrices too far.
 

27" 1ms G2G AU Optronics TN Film + 144Hz (AMA = High)

27" 8ms G2G LG.Display AH-IPS

27" 5ms G2G Samsung PLS (Trace Free = 40)

27" 12ms G2G Samsung PLS (Response Time = Advanced)

We have also provided a comparison of the XL2720Z above against 3 popular 27" high res screens we have tested. The very popular Dell U2713HM showed pretty fast response times for an IPS panel and no noticeable overshoot. The Asus PB278Q and ViewSonic VP2770-LED both feature PLS panels from Samsung, and both were again pretty fast in these tests although in the case of the Asus there was a small amount of overshoot introduced, but not much at all while at the modest Trace Free setting of 40. Again these models weren't as fast as the BenQ in practice, and as we've said earlier they can't offer the same refresh rate or frame rate as the XL2720Z.

 

Blur Reduction

The BenQ XL Z-editions are the first in their range to feature a new 'Blur Reduction' mode. This option is designed to provide a blinking backlight which is controllable from the monitor itself, as opposed to needing to do any third party tweaks for NVIDIA LightBoost or anything else. In our details study of blur reduction backlights we saw there were significant improvements in perceived motion blur when using a strobed backlight like this and we were impressed by the enhanced experience this gave the user for games and dynamic content. You can read our article linked above for full information about how and why this works.

The Blur Reduction mode on the XL2720Z is accessed through the 'Picture' section of the OSD menu and has an option for on and off. When enabled, the screen brightness dips a bit but you can't really see any obvious flickering or anything to the naked eye. Those susceptible to flicker may find it problematic for their eyes, but then this feature shouldn't be enabled during normal uses, only for games and perhaps movies.

Operation

Blur Reduction backlight cycling, 60Hz (scale = 5ms)

We measured the screen using our oscilloscope when viewing a solid white image, with blur reduction feature turned on and with refresh rate set at 60Hz. Normally the oscillograph would show a flat straight line when measuring a static white image (as no PWM is being used for backlight dimming), but here the Blur Reduction feature is cycling the backlight off and on rapidly.

Blur Reduction backlight cycling, 60Hz and 120Hz refresh rate (scale = 5ms)

The time for each cycle is ~8.3ms which shows that in this case the backlight is being cycled at a frequency of 120Hz, i.e. 120 times per second. This is double the 60Hz refresh rate, but matches up as an even number. Cycling at 60Hz to mirror the refresh rate would be too slow and would likely produce a visible flicker, which is why 120Hz cycling has been used. The same result is seen when switching to a 120Hz refresh rate as well. The 'on' period lasts ~1.625ms, with the 'off' period lasting ~6.7ms. This pattern doesn't change, regardless of your brightness setting in the OSD menu.

Blur Reduction backlight cycling, 144Hz refresh rate (scale = 5ms)

If we then change the refresh rate to 144Hz which is the maximum supported by the screen, the Blur Reduction cycling syncs with this refresh rate. It is now cycled every 6.94ms to mirror each frame at 144 fps. The 'on' period lasts ~1.375ms, with the 'off' period lasting ~5.625ms. This pattern doesn't change, regardless of your brightness setting in the OSD menu.

Brightness Adjustment Range

With the Blur Reduction feature on we measured the luminance adjustment range of the screen. With the feature turned off the screen was adjustable between ~282 (100%) and 66 cd/m² (0%). With the feature enabled the range was far more limited. At a setting of 100% brightness the screen only reached up to 118.6 cd/m² maximum, that being the recommended luminance for LCD screens in normal lighting conditions. If you use this feature you may well need to bump the brightness setting up to something higher. The lower maximum luminance is a limitation of these kind of strobed backlights, although they are higher than what is achievable when using third party LightBoost tweaks on other screens at least.
 

Colour and Other Setup Characteristics

We wanted to test the impact on the setup of the screen when enabling the Blur Reduction feature to see whether it has a knock-on effect to white point, gamma or colour accuracy. You can see straight away that it impacts the luminance of the screen, which we will also measure.

BenQ XL2720Z - Calibrated Settings, Blur Reduction OFF

   

Above is our calibrated state from earlier on in the review, with the Blur Reduction feature turned off.

BenQ XL2720Z - Calibrated Settings, Blur Reduction ON

When you turn Blur Reduction on you are left with a fairly similar setup thankfully, and there isn't any major impact to the image other than the reduced luminance. When we'd tested LightBoost we'd seen a fairly big impact to the white point but that was not a problem here with the natively supported Blur Reduction mode. The white point has strayed slightly from the calibrated 6505k point, now being slightly cooler at 6608k and leaving a 2% deviance. Gamma and colour accuracy remain very comparable to before although there is a slightly higher dE in the blue shades now. The luminance has dropped from 119 cd/m² to 71 cd/m² now though which we know is the main difference when enabling Blur Reduction.
 

Blur Reduction Tests

Of course the main thing we want to test is what improvements the Blur Reduction mode offers when it comes to motion clarity and gaming. We were pleased with the results we'd seen from LightBoost backlights when we tested them, and also from the natively supported blur reduction feature on the Eizo Foris FG2421 display (Turbo 240 mode). So we were keen to understand if BenQ had achieved something similar to further enhance their popular XL gaming series.

Some early users and testers have reported issues with the Blur Reduction feature in practice, referred to by www.Blurbusters.com for instance as a "strobe crosstalk" issue. This isn't a bug as such and it's important to understand that. It is a characteristic of the panel operation and the implementation of the strobe backlight. The same kind of thing happens with other strobe backlights including LightBoost methods, it's just manifested in different ways.

With the XL2720Z Blur Reduction feature basically what they have observed is that the Blur Reduction improves motion clarity in certain areas of the screen, but leaves a rather obvious ghosting and blurring on other parts. If you refer to the test images below from the BlurBusters TestUFO online motion test (full screen, 120fps at 120Hz) you can see what we mean, and we observed the same thing when initially testing the Blur Reduction feature on the XL2720Z:

Strobe cross-talk from default Blur Reduction operation. Image courtesy of BlurBusters.com. Click for larger version

The top portion of the screen shows a sharp and clear image, and with the Blur Reduction feature enabled there is a marked improvement in image clarity, and your ability to track the moving objects across the screen. From about half way down the screen and below, the cross-talk issue manifests itself and you see some noticeable ghost images. Since the centre of the screen is most important for gaming as it is where the player is most commonly focusing, it is important to ensure this section is blur free and does not suffer from ghosting problems caused by the strobe cross-talk. The location on the screen of the cross-talk is the reason why it is being referred to as an issue. The Blur Reduction feature still provides benefits in fast gaming and motion, and you can certainly see the improvements with the naked eye, making it easier to track objects across the screen and greatly reducing the perceived motion blur.

In an ideal World the user would have some control over the strobe phase setting which if adjusted basically would allow the user to choose where on the screen is clearest and to suit their taste, whether that's providing the blur improvement at the top, middle or bottom region. Some degree of cross-talk is unavoidable and it's important to understand we're only really talking about being able to "move" where the clearer regions are. Other adjustment options to improve motion clarity are also an additional useful option if they can be provided by the manufacturer.

Thankfully there is a handy solution to help users control the Blur Reduction feature a bit more if they want to, or if they are dissatisfied with the native operation of the strobe. BlurBusters have released their own utility which can be used with the new XL-Z series screens and allows the user to tweak aspects of the Blur Reduction control to improve overall performance. This isn't a BenQ utility and is not something they support, but users can test it fairly easily and hopefully obtain better motion blur clarity as a result or tweak things to their taste. To get the Blur Busters Strobe Utility click here.

What BenQ have done is develop a firmware update which allows the user to make use of third party adjustment utilities, and provides the user with an option to control more aspects of the Blur Reduction feature if they want to. See their Press Release as well for more information. They don't support the third party utilities, and they aren't  BenQ tools, but it's nice to see them open the screen up a bit to meet the requirements of gamers out there, or those who like to adjust things a bit themselves.

To use the Blur Busters Strobe Utility you must have an XL-Z series monitor with a compatible firmware revision. The earliest shipped units with Rev 1 firmware do not allow the use of this utility or control over the strobe settings unfortunately. You can download the new firmware from the BenQ website but there is no simple way for the user to update the firmware themselves as it requires additional hardware and software. You may be able to buy third party solutions to allow firmware upgrades but that is of course entirely at your own risk and BenQ cannot support that. An easier solution for Rev 1 units in Europe is that BenQ have offered to update the firmware for users if they want. The user must pay for shipping costs to and from the service centre, but BenQ will do the firmware update for those people if they desire. Users should contact the BenQ support through the relevant country website for more information. We don't know what other BenQ regions outside of Europe are planning to do with early Rev 1 units at this time though.

Obviously they only need to bother doing this if they want to be able to tweak the Blur Reduction feature themselves with the third party utilities. The updated Rev 2 firmware doesn't do anything else other than open up commands for these utilities, so brings no additional benefits. The Blur Busters Strobe Utility identifies if you have a compatible screen/firmware connected when you run it (make sure you have the monitor driver installed). You may also be able to tell from the factory OSD menu at some point although we don't know yet what this will look like for Rev 2 versions.

The stock already in supply chains and available in the UK and Europe at the time of writing is the original Rev 1 firmware. It will take a while before BenQ start to ship units with the updated firmware, and longer still for them to make their way into supply chains. There is confusion on the internet about which units may have which firmware version, with the date of December 17th, 2013 being specifically mentioned for example as a firmware date to look out for to give you Rev 2. This is not linked to manufacturer date though and you could just as easily have a unit manufactured in Feb 2014 with a pre December 17th firmware date. At this time even recent manufactured units have V1 firmware whose firmware dates are all dated prior to mid-December. BenQ HQ and BenQ Taiwan confirmed that no Rev 2 units have been shipped yet at the time of writing. Obviously once the Rev 2 firmware does start to ship, there will be a point where users can use the utilities from the outset without any firmware updates needed. In the mean time, if you buy an XL-Z series screen and decide you want to be able to adjust the Blur Reduction settings and you're in Europe, then you can ship it to a BenQ service centre to get that done without much fuss.
 

BlurBusters Utility Tests

Strobe cross-talk from adjusted Blur Reduction operation using BlurBusters utility.
 Image courtesy of BlurBusters.com. Click for larger version

We tried the updated firmware with the Blur Busters Strobe Utility as well to test it. BenQ were kind enough to provide us with an updated firmware to test for this review. Within the utility you have two useful options to play with:

• Persistence Setting -  The 'Persistence' slider controls the 'off' period of the strobe function. As you move towards the "clearer motion" end of the scale, the 'off' period is increased, and as a result the screen gets darker. This does serve to improve the motion clarity a bit and people with a keen eye may well notice some improved blur reduction as you get to the lower settings. You do have to contend with darker content though, and it's similar to what we saw when we tested the different LightBoost levels in our Motion Blur Reduction Backlights article. Basically this option provides you a similar control to a LightBoost setting, controlling the length of the 'off' period of the strobe and therefore controlling the visibility of remaining motion blur. By default the BenQ native Blur Reduction feature doesn't give you this level of control, and we measured the on and off periods at the beginning of this section of the review. With the Rev 2 firmware and the BlurBusters utility you have this added option to play with. There's an interesting additional comparison of different LightBoost settings at BlurBusters here which also applies to controlling the strobe length on the XL2720Z using this utility. This is more of a "bonus" feature to the tool than the main reason it was introduced which was for...
   

• CrossTalk setting - The second slider is for the 'crosstalk' setting, allowing you to adjust the strobe timing to alter the behaviour of the strobe. This is the option which can help you alter the behaviour of the ghosting issue and strobe cross-talk we talked about earlier if you find it a problem. By changing the strobe phase to move it earlier or later you can basically change which sections of the screen show the clearest image, and which show some ghosting still. You can't eliminate the ghosting from the whole screen, but you can at least change its location. So for example you can improve the clarity in the central region of the screen which will probably improve your overall gaming experience in many situations. The sample photo above shows that the "clear" region is now central, but you will still see ghosting cross-talk issues at the bottom, and now also some at the top. To re-iterate, the utility/firmware doesn't eliminate all the cross-talk, it just allows you to alter where the cross-talk appears for improved user experience.

So the utility certainly offers you a bit more flexibility to control the strobe phase timing, to move the clear sections of the image to your liking, and to adjust the strobe length if you want to try and alter the motion clarity a bit, at the cost of some brightness. There is also an additional "tweak" users can make if they want using the so-called "ToastyX CRU 1350-line Vertical Total Trick". This doesn't require the new firmware of the use of the BlurBusters tool, it is just an additional tweak you can use which can help improve the motion clarity further. This on its own may be enough of an improvement for a lot of users even with the default Blur Reduction operation so it's worth having a look at if you really want to try and tweak the settings to get the best motion performance possible. The highest level of control would be using the Blur Busters Strobe Utility and the ToastyX tweak.
 

We had already found the blur reduction feature to work well, eliminating a lot of the perceived motion blur for the user and making tracking of moving images much easier. With the updated firmware and Blur Busters Strobe Utility it was nice to be able to change which region of the screen was the clearest, particularly so we could make the central region more blur-free. The additional persistence alteration was a nice extra too, allowing us to sacrifice a bit of brightness in favour of a clearer image. All in all the blur reduction feature worked well, and was similar to what we'd seen from other recent methods like LightBoost and Eizo's Turbo 240. Whether users will need or want to make their own adjustments to the blur settings will no doubt vary, and some users may well be perfectly happy with the default behaviour. If you want to be able to make your own adjustments then you can send your XL-Z screen back to BenQ to have the firmware updated, and at some point future stock will allow the use of these utilities anyway.
 

Additional Gaming Features

Aspect Ratio Control - The XL2720Z supports a massive range of aspect ratio control options through the OSD 'display mode' option as shown below. There are options for:

• Full - interpolation of the input image to fill the screen, no matter what the aspect ratio is of the source

• Aspect - maintains the source aspect and fills as much of the screen as possible

• 1:1 - maps the image source resolution to the screen with 1:1 pixel mapping

• Defined screen sizes and aspects - a whole range of different screen sizes and aspect ratios are simulated, including options at 4:3, 16:9 and 16:10 aspect ratios of different sizes.

Good to see a defined 1:1 pixel mapping option available and a mode to automatically detect and interpolate the source aspect ratio. Looks like BenQ have thought of pretty much everything here for gaming at different preferred resolutions. Also useful for connection of external games consoles etc not running at 1920 x 1080 resolution.
 

Preset Modes - There are several preset modes aimed at gamers. These include:

• FPS 1 and 2 - designed for playing First Person Shooter games. BenQ's documentation states: "Meet your secret winning strategy. The FPS Mode was co-developed with gaming legends to let you tap into the fundamental insights of pro gamers and view the game how a gaming legend would see it. This out-of-the-box preset automatically adjusts your monitor calibrations to provide you with optimal brightness, contrast, sharpness and colour tint. Being able to spot your enemies and track their move carefully in every situation put you at an advantage over your opponents. There are two variations to this special mode: the FPS1 mode is designed to configure and optimize the display for Counter-Strike 1.6 and the FPS2 mode for Counter-Strike Source as recommended by BenQ. The perfect combination of form and function provides gamers with the vantage point to always be one step ahead of the game."
   

• RTS - designed for playing Real-time Strategy games
   

• Gamer modes 1, 2 and 3 - 3 customisable preset modes which can be saved to your own personal tastes. You can then control these easily and switch between them using the provided S Switch device.

Above: S Switch for quick switching between custom gamer preset modes

Each of the FPS and RTS presets seems to boost the colours of the image displayed. They actually look to be a bit oversaturated and are set up to provide bright and vivid colours. We have already seen that the actual accuracy is poor out of the box (we tested the default FPS 1 mode) but then they are deliberately not set up for day to day accuracy, but are designed for specific gaming scenarios.

Black eQualizer

According to the documentation, "poor visibility in dark scenes can cost even the most skilful gamers their game. The Black eQualizer colour engine technology is designed to offer an unprecedented level of control and visibility. Dark scenes are brightened without over-exposing the bright areas to preserve vital details, enabling gamers to spot their enemies easily in critical combat and react quickly in any situation." We have tested this feature before and found it beneficial in altering the gamma of dark grey shades and helping to bring you detail in darker content.
 

Game Mode Loader

BenQ have also added the ability for the user to download special gaming presets, used by HeatoN and SpawN, so you can see what the pros see. BenQ's website states: "The secret is out. Download special gaming preset calibrations used by well-known gamers so you can see what the pros see. Each mode is fine-tuned, so you can steal these exclusive presets used by pro gamers to your own advantage. You can even save your favorites on the S Switch for quick access and game play. More presets will be released in the future to keep you on top of your game. Download Game Mode Loaders"
 

NVIDIA 3D Vision 2

The XL2720Z screen continues to support stereoscopic 3D content through the use of NVIDIA's active shutter glasses and transmitter. These need to be bought separately, but it's good to see the continued support for 3D content. BenQ's website states: "Certified as NVIDIA 3D Vision 2-ready with the new NVIDIA 3D LightBoost technology to provide you with brighter and clearer 3D images. Now you can experience gaming and entertainment like never before with total realism and intensive 3D graphic display."

Lag

For the full reviews of the models compared here and the dates they were written (and when screens were approximately released to the market), please see our full reviews index.

We have provided a comparison above against other models we have tested to give an indication between screens. Those shown with blue bars in the bottom half represent the total "display lag" as at the time of review we did not have access to an oscilloscope system to measure the response time element and provide an estimation of the signal processing. The screens tested more recently in the top half are split into two measurements which are based on our overall display lag tests (using SMTT) and half the average G2G response time, as measured by the oscilloscope. The response time is split from the overall display lag and shown on the graph as the green bar. From there, the signal processing (red bar) can be provided as a good estimation.

The BenQ XL2720Z features a special "Instant Mode" feature in the OSD menu which when activated, bypasses some of the internal electronics to reduce the signal processing lag. We measured the display lag with this turned on and off for comparison.

With Instant mode off, we had a total display lag from SMTT of 10.0ms. With half the average G2G response time accounting for ~1.9ms of that, we can estimate a signal processing lag of ~8.1ms. When instant mode is turned on, the overall display lag drops nicely to only 3.2ms, so again with 1.9ms of that from pixel response times, we can estimate a very low signal processing lag of 1.3ms which is excellent. These figures remain constant at each refresh rate setting incidentally. For gamers, using the instant mode setting helps reduce the lag nicely, and is so low that you shouldn't notice it at all, even for professional gaming and FPS games.
 

Gaming Summary

We've looked at a lot of aspects of the gaming experience on the XL2720Z in the last few sections so thought it would be useful to summarise them here. Firstly from a pixel response time point of view we established that the AMA High setting offered the best balance between low response times and moderate overshoot. It improved significantly the rather slow response times with AMA set to Off, and introduced some overshoot in certain transitions only which wasn't overly problematic. Running the screen at the maximum 144Hz refresh rate is advised of course, providing you with the highest frame rate support (144fps), the smoothest on screen movement and also helping to reduce the appearance of overshoot somewhat. It can also be used for 3D gaming if you want via NVIDIA 3D Vision 2. The pixel response times were very fast which is a benefit of the TN Film panel technology being used.

Gamers will be pleased with the very wide range of additional extras to enhance their experience as well we're sure. The Black eQualizer setting works well at boosting gamma in dark content, the S-switch is useful if you need to switch between different saved modes often and the very wide range of aspect ratio control options should provide you with everything you could need when it comes to scaling. The lag of the display is also very low, especially when you switch 'Instant mode' on, which we would recommend for fast gaming. The new Blur Reduction feature works very well at reducing perceived motion blur, just like we'd seen from other technologies in the past. The position of the strobe cross-talk in the central region of the screen is a bit of a problem in some cases, and it's nice to have the flexibility of the BlurBusters utility to make adjustments to that if you need to. This won't be needed by everyone though and some people will find the default behaviour fine. There are a couple of additional tweaks you can play with when it comes to blur reduction which we've already talked about, if you really want to try and squeeze that last bit of performance out of the screen.

Movies and Video

The following summarises the screens performance in video applications:

• 27" screen size makes it a reasonable option for an all-in-one multimedia screen, but being quite a bit smaller than most modern LCD TV's of course.

• 16:9 aspect ratio is more well suited to videos than a 16:10 format screen, leaving smaller borders on DVD's and wide screen content at the top and bottom.

• 1920 x 1080 resolution can support full 1080 HD resolution content

• Digital interface support HDCP for any encrypted and protected content

• DVI, VGA, DisplayPort and 2x HDMI connections available, offering great connectivity choices for modern DVD players, Blu-ray, consoles etc.

• Cables provided in the box for VGA and DVI, but not DisplayPort or HDMI.

• Medium AG coating provides clear enough images with no major graininess, and without the unwanted reflections of a glossy solution.

• Wide brightness range adjustment possible from the display, including high maximum luminance of ~282 cd/m² and a good minimum luminance of ~66 cd/m². This should afford you very good control for different lighting conditions. Contrast ratio remains stable across that adjustment range as well, and brightness regulation is controlled without the need for PWM which is great news.

• Black depth and contrast ratio are excellent for a TN Film panel at 950:1 after calibration. Detail in darker scenes should not be lost as a result, and shadow detail should be good.

• There is a specific 'movie' preset mode available for movies or video if you want which is a little cooler and gives an accentuated sharpness. If you don't want to use that you can easily set up one of the 3 customisable modes instead for your movie uses.

• Excellent pixel responsiveness which can handle fast moving scenes in movies without issue. Some overshoot issues on some transitions when using the optimum AMA High mode. If they prove distracting in movies, switching AMA Off might be an option worth trying.

• 120Hz+ refresh rate support allows for stereoscopic 3D content with relevant active shutter setup from NVIDIA. Viewing 3D movies is possible on this screen as a result.

• Viewing angles are limited due to the use of TN Film panel technology. May cause issues with gamma and contrast shift if you change your line of sight or have several people trying to see the screen at once. Not really an ideal technology for movies as a result of this viewing angle limitation.

• Very good range of ergonomic adjustments available from the stand, so should be easy to obtain a comfortable position for multiple users or if you want to sit further away from the screen for movie viewing.

• No particularly noticeable backlight leakage, although a slight glow along the bottom edge was detected in darkened conditions

• No integrated stereo speakers on this model but there is a headphone jack if sending sound to the screen over HDMI.

• Excellent range of hardware aspect ratio options which should provide you any option you need.

• Picture in picture (PiP) and Picture By Picture (PbP) are not available.
   

Conclusion

The BenQ XL2720Z was an interesting screen to review, as it really does offer a lot of extra features and new things to test out. Obviously gaming is the primary target for this screen and gaming is something it does very well. We will try not to repeat too much what we've already said in the extensive coverage above, but the screen offers very low response times, no major overshoot, 144Hz refresh rate support, very low input lag and a great array of additional gaming features which are actually largely very useful. The aspect ratio control options are extensive, the Black eQualizer works well and the new Blur Reduction feature provides a new level of motion clarity not seen from previous XL series monitors. Clearly BenQ are working hard to meet the demands of gamers and continuing to provide all those extra things which make this a premium gaming screen.

Gaming aside for a minute, we were also please with other aspects of the screen. The new flicker free backlight is very welcome, and the brightness range of the screen is also very good. The Low Blue Light mode worked well to reduce the blue spectrum of the W-LED backlight and was an interesting new feature in their EyeCare initiative. Default setup in the 'standard' mode was adequate for some general use and the screen offered a high contrast ratio for this panel technology which was nice. You do have to live with the limitations of TN Film technology still, with restrictive viewing angles being the main issue still. BenQ haven't scrimped in other extras either, with a versatile stand, good range of connections and premium features like touch-sensitive buttons being provided.

If you're looking for a very good gaming screen with a wide range of premium features and useful extras, the XL2720Z is an excellent choice.

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