

Introduction

The Predator range of monitors has been gaining momentum in the display market for about 18 months now, as Acer continue to invest in the latest technologies and try to offer buyers something interesting and different. They were first to market back in Feb 2015 with a 144Hz high refresh rate IPS-type panel in the form of the very popular XB270HU. They were also first to market with an overclocked 100Hz compatible 34" IPS 3440 x 1440 display, in the form of the X34. We've reviewed a fair few different models from the Predator range now, in different sizes and with different panel technologies, specs and features. We now have with us the brand new Z271 which offers something a little different yet again, and is another first for the market.

The Z271 is a 27" sized screen featuring a curved VA panel and 1920 x 1080 resolution. Interestingly this is the first high refresh rate VA panel available from the panel manufacturer Samsung, offering a 144Hz native refresh rate. It's combined with NVIDIA G-sync and a range of extras and features which we've become accustomed to from the Predator range. We should say up front that for some reason ULMB is not available on this model, despite the G-sync module, which is a bit of a shame. We will put the new panel through our tests and see what kind of performance this new gaming monitor offers for those wanting something a bit different from the usual TN Film and IPS panels in the market.

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Specifications and Features

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

Monitor Specifications Size 27"WS (68.6cm) Panel Coating Light AG coating Aspect Ratio 16:9 curved 1800R Interfaces 1x DisplayPort 1.2a, 1x HDMI Resolution 1920 x 1080 Pixel Pitch 0.3113 mm Design colour Matte black plastics with some dark red trim on the stand Response Time 4ms G2G Ergonomics Tilt, 120mm height, swivel Static Contrast Ratio 1000:1 (3000:1 actual) Dynamic Contrast Ratio 100 million:1 VESA Compatible Yes 100mm Brightness 300 cd/m2 Accessories Power cable and brick, DisplayPort, USB cables Viewing Angles 178 / 178 Panel Technology Samsung SVA Weight Approximate: 7.6 Kg Backlight Technology W-LED Physical Dimensions (WxHxD)

619 x 519.2 x 268.5 mm Colour Depth 16.7m Refresh Rate 144Hz

G-sync range 30 - 144Hz Special Features 4x USB 3.0 ports (2 with charging), headphone jack, ambient light system, 2x 7W speakers Colour Gamut Standard gamut sRGB

The Z271 offers a limited range of connectivity options with only DisplayPort 1.2a, and HDMI offered, although these are probably sufficient for many users anyway. This limitation is due to the use of a G-sync module which at this time has limited input support and no scaler. The digital interfaces are HDCP certified for encrypted content and the video cables are provided in the box for DisplayPort only.

The screen has an external power supply and comes packaged with the power cable and power brick you need. There are also 4x USB 3.0 ports located on the back of the screen with two having charging capabilities as well. An audio headphone jack is also provided in case you don't want to use the built-in 2x 7W speakers but are sending sound to the screen.

One additional note is with the static contrast ratio spec. For some reason Acer list this as 1000:1 on their webpage and in the spec sheets they sent us. We know that the Samsung VA panel being used has a spec of 3000:1 though, which is typical for a modern VA panel. In reality, that's the kind of static contrast ratio we measured, hence referencing 3000:1 in the table above. Acer will probably correct their spec we would have thought.

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

Feature Yes / No Feature Yes / No Tilt adjust DVI Height adjust HDMI Swivel adjust D-sub Rotate adjust DisplayPort VESA compliant Component USB 2.0 Ports Audio connection USB 3.0 Ports HDCP Support Card Reader MHL Support Ambient Light Sensor Integrated Speakers Human Motion Sensor PiP / PbP Touch Screen Blur Reduction Mode Factory Calibration G-Sync Hardware calibration FreeSync Uniformity correction Wireless charging





Design and Ergonomics



Above: front views of the screen. Click for larger versions The Z271 comes in a mostly black design, with some maroon trim on the stand as you can see above. The black plastics are a matte finish as opposed to glossy plastics used on some older Predator screens. There is an ~8.5mm black plastic border around the sides and top, and then a small 2 - 3mm black panel border as well before the image starts. Along the bottom edge of the screen the bezel is thicker at ~23mm. There is a shiny silver and red 'Predator' logo in the middle of the bottom bezel and a small power LED is also visible on the front edge in the bottom right hand area. This glows blue during normal operation and amber in standby. There are no other labels or writings on the front of the screen at all apart from a removable NVIDIA G-sync sticker.

Above: front and rear views of the screen. Click for larger versions The bottom bezel is finished in a 'spotty' textured plastic, which is the same on the lower part of the plastic on the back of the screen. The rest of the back of the screen in the upper area is a black plastic but is given a brushed aluminium style finish which looks nice. You will note the USB hub on the back of the screen in the bottom right hand area. Also the red OSD control joystick and buttons in the bottom left hand area.

Above: view of the base of the stand. Click for larger version The base of the stand has some maroon coloured aluminium sections and provides a wide, sturdy and strong base for the screen. The supporting arm is chunky and stable also, and there is a cable tidy hole in the arm at the bottom which is useful.

Above: full tilt adjustment range shown. Click for larger versions There is a decent tilt adjustment range offered from the stand which is smooth and easy to use.

Above: full height adjustment range shown. Click for larger versions Height adjustment is also available with smooth movement and a pretty easy to use mechanism. At the lowest setting the bottom edge of the screen is ~30mm from the top of the desk, and at maximum extension it is ~150mm. This gives a total adjustment range of ~120mm which is decent and as advertised. Side to side swivel is also available and is again smooth and pretty easy to use. There is no rotation function offered here, probably due to the curved screen format. The screen remains pretty stable on the stand as you move it around and there's very little wobble. A summary of the screens ergonomic adjustments is shown below: Function Range Smoothness Ease of Use Tilt Yes Smooth Easy Height 120mm Smooth Pretty easy Swivel Yes Smooth Easy Rotate No - - Overall Smooth and easy movements from available adjustments. Stable with very little wobble. The materials were of a good standard and the build quality reasonable as well. It did feel a bit more chunky and basic than some other screens but it still looked pretty nice. There was no audible noise from the screen, even when conducting specific tests which can often identify buzzing issues. The whole screen remained cool even during prolonged use as well which was pleasing.

Above: interface connections shown. Click for larger version The back of the screen offers the interface connections for DisplayPort and HDMI, along with the power brick connection and a headphone jack. On the back of the screen is the USB upstream and 4x USB 3.0 downstream ports as shown below.

Above: USB hub on the back of the screen. Click for larger version





OSD Menu



Above: OSD control joystick and control buttons on back right hand side (as viewed from the front).

Click for larger version

The OSD menu is controlled through 3 pressable buttons and a joystick control on the back right hand edge of the screen . You have to feel your way behind the screen to use these, and there is also a power button located here at the top with a slight separation from the other buttons. We did sometimes find ourselves pressing the power button accidentally which was a bit of a pain. The joystick is also pressable and acts as the main control for the OSD menu. Pressing any of the buttons brings up the quick access menu as shown above. By default there is access to the preset mode menu, brightness control and input selection. You can customise these options via the main menu which is useful in case you need regular access to something specific. Oddly the 'modes' menu is only available if you have it selected as one of the quick access options. It is not available in the main OSD elsewhere. Probably an over-sight from Acer there. From the initial quick access menu, pressing the joystick button in brings up the main OSD menu. This main menu is split in to 6 sections down the left hand side, with the options available in each then shown on the right hand side. The 'picture' section has all the usual controls for brightness, contrast etc. You can also use the blue light modes here if you want, or the 'dark boost' feature for gaming. The 'color' section has controls for the gamma, colour temp and RGB channels which will be useful for calibration. The other sections are pretty self-explanatory from the above images. In the 'system' menu you can control the ambient light feature as well: This feature provides a nice projected light from the bottom edge of the screen which can be customised in terms of colour and behaviour. There's even an option to match the light colour to the colour of the content on the screen, a little like Philips AmbiLight function on some of their TV's. The ambient light feature on this screen adds a nice premium extra and looks pretty cool in use. All in all the OSD menu offered a good range of options and lots to play with. We felt navigation was mostly pretty easy thanks to the joystick control, although the buttons on the back sometimes resulted in accidental powering off of the screen. The joystick felt a little flimsy too but overall we felt it was intuitive to use.



Power Consumption

In terms of power consumption the manufacturer lists typical usage of 33W and 0.5W in standby. We carried out our normal tests to establish its power consumption ourselves.

State and Brightness Setting Manufacturer Spec (W) Measured Power Usage (W) Default (80%) 33.0 34.2 Calibrated (27%) - 24.0 Maximum Brightness (100%) - 37.6 Minimum Brightness (0%) - 19.1 Standby 0.5 0.5

We tested this ourselves and found that out of the box the screen used 34.2W at the default 80% brightness setting. Once calibrated the screen reached 24.0W consumption, and in standby it used only 0.5W. We have plotted these results below compared with other screens we have tested. The consumption is comparable to the other 27" sized screens we have tested as you might expect, with some of the smaller screens drawing less power and the larger screens drawing more (comparing the calibrated states).





Panel and Backlighting

Panel Manufacturer Samsung Colour Palette 16.7 million Panel Technology SVA Colour Depth 8-bit Panel Module LTM270HP02 Colour space Standard gamut Backlighting Type W-LED Colour space coverage (%) ~sRGB, ~72% NTSC

Panel Part and Colour Depth

The Acer Predator Z271 features a Samsung LTM270HP02 SVA (Vertical Alignment type) technology panel which is capable of producing 16.7 million colours. This is achieved through a 8-bit colour depth. The panel part is confirmed when dismantling the screen as shown below:

Screen Coating

The screen coating is a pretty light anti-glare (AG) offering. It isn't a semi-glossy coating as some VA type panels have, but thankfully it isn't a heavily grainy coating like some old IPS panels feature. It is also lighter than modern TN Film 'medium' panel coating. It retains its anti-glare properties to avoid too many unwanted reflections of a full glossy coating, but does not produce an too grainy or dirty an image that some thicker AG coatings can.



Backlight Type and Colour Gamut

The screen uses a White-LED (W-LED) backlight unit which is standard 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. Acer quote 100% sRGB coverage in their spec. Anyone wanting to work with wider colour spaces would need to consider wide gamut CCFL screens or the newer range of GB-r-LED type (and similar) displays available now. 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 = 5ms

At 100% brightness a constant voltage is applied to the backlight. As you reduce the brightness setting to dim the backlight a Direct Current (DC) method is used, as opposed to any form of PWM. This applies to all brightness settings from 100% down to 0%. The screen is flicker free as a result as advertised, which is great news.

Pulse Width Modulation Used No Cycling Frequency n/a Possible Flicker at 100% Brightness No 50% Brightness No 0% Brightness No



Contrast Stability and Brightness

We wanted to see how much variance there was in the screens contrast as we adjusted the monitor setting for brightness. In theory, brightness and contrast are two independent parameters, and good contrast is a requirement regardless of the brightness adjustment. Unfortunately, such is not always the case in practice. We recorded the screens luminance and black depth at various OSD brightness settings, and calculated the contrast ratio from there. Graphics card settings were left at default with no ICC profile or calibration active. Tests were made using an X-rite i1 Display Pro colorimeter. It should be noted that we used the BasICColor calibration software here to record these, and so luminance at default settings may vary a little from the LaCie Blue Eye Pro report.

OSD Brightness Luminance

(cd/m2) Black Point (cd/m2) Contrast Ratio

( x:1) 100 338.84 0.11 3080 90 311.97 0.10 3120 80 286.43 0.10 2864 70 256.63 0.09 2851 60 227.93 0.08 2849 50 197.58 0.07 2823 40 166.72 0.06 2779 30 134.01 0.05 2680 20 100.62 0.03 3354 10 65.22 0.02 3261 0 29.15 <0.02 -

Total Luminance Adjustment Range (cd/m2) 309.69 Brightness OSD setting controls backlight? Total Black Point Adjustment Range (cd/m2) >0.09 Average Static Contrast Ratio 2966:1 PWM Free? Recommended OSD setting for 120 cd/m2 26

We conducted these tests in the default 'standard' preset mode. The brightness control gave us a very good range of adjustment. At the top end the maximum luminance reached 339 cd/m2 which was a little higher even than the specified maximum brightness of 300 cd/m2 from the manufacturer. There was a decent 310 cd/m2 adjustment range in total, and so at the minimum setting you could reach down to a nice low luminance of 29 cd/m2. This should be adequate for those wanting to work in darkened room conditions with low ambient light. A setting of 26 in the OSD menu should return you a luminance of around 120 cd/m2 at default settings in this preset mode. It should be noted that the brightness regulation is controlled without the need for Pulse Width Modulation, using a Direct Current (DC) method for all brightness settings between 100 and 0% and so the screen is flicker free.

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 is a linear relationship as you can see.

The average contrast ratio of the screen was excellent at 2966:1. This was basically on par with the Samsung panel spec of 3000:1 and certainly a strong point of this VA technology. We have not provided the usual contrast stability graph, as at these kind of black depths the rounding errors introduce too much variance.





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.

We restored our graphics card to default settings and disabled any previously active ICC profiles and gamma corrections. The screen was tested at default factory settings using an X-rite i1 Pro 2 Spectrophotometer 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 2 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/m 2 , 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:

Monitor OSD Option Default Settings Preset mode Standard Brightness 80 Contrast 50 Gamma 2.2 Color Temp Warm RGB 50, 50, 50 (locked)



Acer Predator Z271 - Default Settings











Default Settings luminance (cd/m2) 294 Black Point (cd/m2) 0.10 Contrast Ratio 2864:1

Initially out of the box the screen was set in the default 'standard' preset mode. With the brightness set at a high 80% level, and so out of the box the screen was overly bright and uncomfortable to use. You will definitely need to turn that down to something lower for prolonged use. You could tell the screen was using a standard gamut backlight as well with the naked eye, and the colour balance and temperature felt good.

We went ahead and measured the default state with the i1 Pro 2. The CIE diagram on the left of the image confirms that the monitors colour gamut (black triangle) is fairly equal to the sRGB colour space. There is some minor over-coverage in greens and blues, but not by anything significant. Default gamma was recorded at 2.1 average, leaving it with a minor 3% deviance from the target which was good news as gamma can be tricky to correct without a calibration device. White point was measured at a reasonably accurate 6275k, being 3% out from the 6500k we'd ideally want for desktop use.

Luminance was recorded at a very bright 294 cd/m2 which is too high for prolonged general use. The screen was set at a default 80% brightness in the OSD menu but that is easy to change of course to reach a more comfortable setting without impacting any other aspect of the setup. The black depth was an impressive 0.10 cd/m2 at this default brightness setting, giving us a very strong static contrast ratio of 2864:1. Colour accuracy was also good out of the box with an average dE of 1.8. Testing the screen with colour gradients showed smooth transitions in all shades, with some gradation evident in the very dark tones. Overall this default setup was good and we were pleased with the results.

Calibration

We used the X-rite i1 Pro 2 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.

Monitor OSD Option Calibrated Settings Preset Picture Adjust mode User Brightness 27 Contrast 50 RGB 42, 48, 48 Gamma 2.2 Colour Temp User



Acer Predator Z271 - Calibrated Settings







Calibrated Settings luminance (cd/m2) 120 Black Point (cd/m2) 0.047 Contrast Ratio 2529:1

When you start changing the brightness control or RGB levels, you automatically move in to the 'user' preset mode. We adjusted the RGB channels and brightness setting as shown in the table above. All these OSD changes allowed us to obtain an optimal 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 was now corrected to 2.2 average with a 0% deviance, correcting the small 3% deviance we'd seen out of the box. The white point had now been corrected to 6524k, which again corrected the small 3% deviance we'd seen out of the box. Luminance had been improved thanks to the adjustment to the brightness control and was now being measured at 120 cd/m2. This left us a black depth of 0.047 cd/m2 and maintained a very strong static contrast ratio of 2529:1. This had dropped slightly due to the reduction in the RGB settings. Colour accuracy of the resulting profile was excellent on the most part, with dE average of 0.8 and maximum of 2.5 where red shades seemed to be a little tricky to correct. LaCie would consider colour fidelity to be very good overall. Testing the screen with various colour gradients showed smooth transitions. There was some gradation in darker tones and some very slight banding introduced in the very dark end due to the adjustments to the graphics card LUT from the profilation of the screen. 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 out of the box was good overall, with a small deviance only in the gamma curve and white point (3% on each). The screen offered a low dE and strong static contrast ratio and should be fine for most normal users without the need for calibration equipment. It was a bit more accurate than many of the other 27" sized screens we've tested, which sometimes were set up more specifically for gaming and therefore showed a much lower gamma (e.g. Acer XG270HU = 1.8 gamma average).

The display was very strong when it came to black depth and contrast ratio thanks to the use of a VA panel from Samsung. With a calibrated contrast ratio of 2529:1 it easily surpassed the wide range of TN Film and IPS-type panels which dominate the 27" market, which can reach up to around 1000:1 to 1100:1 or so in the best cases.

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Viewing Angles



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

Viewing angles of the screen were fairly typical for a VA technology panel. The image became more washed out as you viewed it from a wide angle horizontally, and certainly vertical shifts were even more noticeable with some yellowy colour tone shift evident. The viewing angles were not as good as you will get from an IPS-type panel, but they are better than you will see from TN Film matrices. Somewhere in the middle is VA. The viewing angles here were a bit better than the recent Acer Predator Z35 which showed more washed out colours from off-centre angles.

Users should also be aware that the panel exhibits the off-centre contrast shift which is inherent to the VA pixel structure. When viewing a very dark grey font for example on a black background, the font disappears when viewed head on, but gets lighter as you move slightly to the side. This is an extreme case of course as this is a very dark grey tone we are testing with. Lighter greys and other colours will appear a little darker from head on than they will from a side angle, but you may well find you lose some detail as a result. This can be particularly problematic in dark images and where grey tone is important. It is this issue that has led to many graphics professionals and colour enthusiasts choosing IPS panels instead, and the manufacturers have been quick to incorporate this alternative panel technology in their screens. We would like to make a point that for many people this won't be an issue at all, and many may not even notice it. Remember, many people are perfectly happy with their TN Film panels and other VA based screens. Just something to be wary of if you are affected by this issue or are doing colour critical work.



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

We captured a photo of an all-black image as viewed from a side angle as shown above. This can help exhibit any glow you might see on different panel technologies. On the Z271 the screen showed a pale blue glow from an angle, which was more noticeable than on some other modern VA panels we've tested. It was not as noticeable as a typical IPS panel where the pale white glow can be a problem to some users.





Panel Uniformity

We wanted to test here how uniform the brightness was across the screen, as well as identify any leakage from the backlight in dark lighting conditions. Measurements of the luminance were taken at 36 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. 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 moderate overall. There was a drop in luminance towards the sides of the screen where in the worst case the luminance dropped to 91 cd/m2 (-24%). That was the most extreme example though and in fact 68% of the screen was within a 10% deviance from the centrally calibrated point which was not too bad.



Backlight Leakage



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

We also tested the screen with an all black image and in a darkened room. A camera was used to capture the result. The camera showed there was no major backlight bleed evident, but a some slight clouding evident from the upper corners, and a little more noticeable clouding along the bottom edge of the screen.

Note: if you want to test your own screen for backlight bleed and uniformity problems at any point you need to ensure you have suitable testing conditions. Set the monitor to a sensible day to day brightness level, preferably as close to 120 cd/m2 as you can get it (our tests are once the screen is calibrated to this luminance). Don't just take a photo at the default brightness which is almost always far too high and not a realistic usage condition. You need to take the photo from about 1.5 - 2m back to avoid capturing viewing angle characteristics, especially on IPS-type panels where off-angle glow can come in to play easily. Photos should be taken in a darkened room at a shutter speed which captures what you see reliably and doesn't over-expose the image. A shutter speed of 1/8 second will probably be suitable for this.



General and Office Applications

The Z271 has somewhat of a limited resolution for day to day use and office work, on a screen this size. 27" panels usually offer a nice 2560 x 1440 resolution nowadays, but the Z271 sticks with a lower 1920 x 1080 resolution. This is a limitation of the current VA panel available from Samsung which is only produced as 1920 x 1080 @ 144Hz currently. This resolution is more widely achievable at high refresh rates than if this was a 2560 x 1440 panel, so from a gaming point of view it is arguably more suitable in some ways. However, the comparatively low resolution does become noticeable for general office type work and feels a significant step down from the 1440p models we are used to testing. With a 0.3113mm pixel pitch, fonts look quite large and less sharp than on higher resolution panels. It is probably easier on the eye if you have the screen positioned at a fairly long viewing distance, or if you have weaker eye sight, but we do prefer 1440p models for this type of work by some way. The curved format does add a bit of comfort to the usability of the screen we felt, and the VA panel offered a decent rounded performance for these types of use.

The light AG coating of the panel is welcome and the pretty wide viewing angles provided by this panel technology helps minimize on-screen colour shift when viewed from different angles. They are not as wide as on IPS panels so you need to be aware of that, although the image appears more stable than on TN Film panels where contrast and colour tone shifts are more problematic. The off-centre contrast shift of the VA pixel alignment is annoying in some situations and may be problematic for photo work, so something you need to be aware of as with any other VA panel. The default factory setup of the screen was good, offering a pretty accurate gamma curve and white point, excellent static contrast ratio and low dE.

The brightness range of the screen was also very good, with the ability to offer a luminance between 339 and 29 cd/m2. This should mean the screen is perfectly useable in a wide variety of ambient light conditions, including darkened rooms. A setting of ~26 in the OSD brightness control should return you a luminance close to 120 cd/m2 out of the box. On another positive note, the brightness regulation is controlled without the need for the use of the now infamous Pulse-Width Modulation (PWM), and so those who suffer from eye fatigue or headaches associated with flickering backlights need not worry. 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 are a few extras provided here as well including a 4x port USB 3.0 hub on the back, two with charging support. There is an audio output for headphone connection if you want, with the display also offering 2x 7W stereo speakers. The ambient light system provides an attractive lighting option for darker environments as well which some people will like. There were no further extras such as ambient light sensors or card readers on this model which can be useful in office environments. There was a good range of ergonomic adjustments available from the stand allowing you to obtain a comfortable position for a wide variety of angles of tilt, swivel and height adjustments. The VESA mounting support may also be useful to some people as well.



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 144Hz 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 and clear although quite large on a screen this size as we already mentioned. When running at a the lower resolution the text shows moderate to high levels of blurring. You also lose a lot of screen real-estate as well of course when running at lower resolutions.





Responsiveness and Gaming

Quoted G2G Response Time 4ms G2G Quoted ISO Response Time n/a Panel Manufacturer and Technology Samsung SVA (VA-type) Panel Part LTM270HP02 Overdrive Used Yes Overdrive Control Available to User Over Drive Overdrive Settings Off, Normal, Extreme

The Z271 is rated by Acer as having a 4ms G2G response time which indicate the panel uses overdrive / response time compensation (RTC) technology to boost pixel transitions across grey to grey changes. The part being used is the Samsung LTM270HP02 SVA (VA-type) technology 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 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.





Over Drive Setting

The 'Over Drive' setting is available via the 'gaming' section of the OSD menu as shown above. We will test all three modes to see which is optimal first of all. The comparison here of the Over Drive setting is when tested at the maximum 144Hz refresh rate. We will test the impact of the active refresh rate on response times in a moment, but without giving too much away, the maximum 144Hz delivered optimal response times from the panel.







In the 'off' setting the response times were slow as you might expect from a VA panel with no overdrive. Some transitions were very slow, especially those from black to grey (0 > x). There was no overshoot at all in this mode of course, since the overdrive was turned off, but we had an average G2G response time of 15.9ms which lead to a large amount of blurring in moving content. Switching up to the 'normal' mode improved things quite noticeably to the naked eye, with a sharper and clearer moving image, and a nice reduction in blurring. The average G2G response time was now recorded at 8.0ms with low levels of overshoot creeping in on a couple of transitions. Keep in mind this is quite a small sample set of measurements, so we will take further readings in a moment. At the maximum 'extreme' setting, the response times were pushed even lower, to 6.0 ms G2G average now, but at the cost of some ridiculously high overshoot levels. One transition (0 > 50) even reached down to 1.1ms G2G, but had a huge 556% overshoot! This mode should be avoided as the overshoot was severe and very noticeable in practice in the form of dark and pale halos and ghosting. Stick to the 'normal' mode which was optimal here.

The above examples from the PixPerAn tool should give you a further indication of the motion clarity, blurring etc seen in each of the response time settings. You can see that the overshoot and trails in the Extreme mode are awful!



Refresh Rate







The Z271 supports a native refresh rate of up to 144Hz, without the need for any overclocking. We stuck with the optimal 'normal' response time setting and then tested the pixel transition times and overshoot in a range of refresh rates from 60Hz to 144Hz. As the refresh rate increased, the response times improved somewhat, as it seemed that the selected refresh rate had an impact on the overdrive control. We have seen the same thing from other G-sync screens in the past, so this isn't a surprise. As the refresh rate is increased, the overdrive impulse is more aggressive, helping to ensure response times are pushed lower to meet the growing frame rate demands. At the same time, some overshoot starts to sneak in at the highest refresh rates, where the overdrive is most aggressive, but in this 'normal' mode it is not too bad and only at low to moderate levels. From 100Hz and above you start to see some slight pale halos in the PixPerAn tests for instance.

As you increase the refresh rate you not only get this improvement in pixel response times, but you also get benefits in the way of improved frame rate support for gaming, and also improvements in perceived motion blur. The refresh rate of a sample-and-hold display like this has a direct impact on perceived motion blur, so there are benefits there for the user. The G-sync feature of the Z271 operates in a range from 30 - 144Hz, and so as the refresh rate is dynamically controlled, so too is the overdrive impulse. The G-sync support helps eliminate tearing in games, without the lag or stuttering that older vsync methods introduced and is a very useful technology as ever. Given the high refresh rate support here of 144Hz, it is useful to have a dynamic refresh rate technology included like G-sync to support a wider range of PC's and graphics cards with varying power.



Detailed Response Time Measurements

We stuck with what we consider to be the optimal 'normal' response time setting and these measurements were taken at the maximum 144Hz refresh rate. With this larger measurement set, the average G2G response time was measured at 6.6ms which was actually impressive for a VA panel. Rise times (changes from dark to light shades) were slightly slower on average than the fall times (changes from light to dark shades) but not by much. The lowest response time measured was 3.4ms, reaching below the advertised 4ms G2G figure in fact. We were impressed by the pixel response times here as VA panels are traditionally pretty slow, hence a lot of the delay with producing high refresh rate VA panels. With a 6.6ms G2G average, the response times are just fast enough to keep up with the frame rate demands of running at 144Hz, where a new frame is drawn every 6.94ms (1000ms / 144Hz = 6.94 ms). There are some transitions which are slower than this threshold though and so you may see some slight blurring added as a result in certain scenarios. You may want to experiment with running at 120Hz as well as 144Hz to see how each looks, or if you're using G-sync then the refresh rate will be controlled dynamically for you anyway in line with your frame rate.

If we evaluate the Response Time Compensation (RTC) overshoot then the results are not too bad. There is a bit of overshoot creeping in on a few transitions, mostly changes from white to lighter grey shades, but on the whole there was very little overshoot to be seen at all. We know that pushing the response time setting up to the maximum 'extreme' mode produced some crazy amounts of overshoot, so it was pleasing to see the balance was mostly right in this 'normal' mode. As we discussed in our refresh rate section above, the overdrive impulse is influenced by the refresh rate of the screen so at lower refresh rates the response times will be a little slower, but the overshoot reduces or disappears as you reach towards the lower refresh rate end.



Display Comparisons

The above comparison table and graph shows you the lowest, average and highest G2G response time measurement for each screen we have tested with our oscilloscope system. There is also a colour coded mark next to each screen in the table to indicate the RTC overshoot error, as the response time figure alone doesn't tell the whole story.

The response time performance of the Z271 were good for a VA-type panel, with a 6.6ms G2G response time measured at 144Hz. This was just fast enough overall to keep up with the high frame rate demands, which was good news as we've seen problems in the past where refresh rate is too high to be practical. The Acer Predator Z35 for instance supports up to 200Hz but only really has response times adequate for 100 - 120Hz tops. Beyond that, blurring becomes a real issue. The fairly low levels of overshoot on the Z271 were also good, although you sometimes see some light halos appearing in certain situations at the maximum refresh rate. If you're using G-sync and fluctuating between 30 - 144Hz then the overshoot only really starts to appear at all above about 100Hz.

High refresh rate 144Hz IPS-type panels like the Asus ROG Swift PG279Q and Acer XB270HU can reach lower response times of around 5ms G2G which is a little faster and smoother than the Z271 and we felt the motion clarity was a bit better there. They were also free from any overshoot so are a bit more suited to gaming. TN Film models with high 144Hz refresh rate like the Asus ROG Swift PG278Q and Dell S2716DG reach even lower at around 2.9 - 3.1ms for instance with moderate overshoot. Don't forget that the Z271 doesn't offer any blur reduction backlight either, like ULMB, so the motion clarity cannot compete with those that do (when enabled).

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 " 4ms G2G Samsung SVA @ 144Hz (Over Drive = Normal)

In practice the Predator Z271 showed fairly low levels of blurring on moving images with some overshoot appearing in some transitions. There wasn't much overshoot detected in these specific colour transitions in the PixPerAn tool, but we saw some pale halos on some test patterns elsewhere.



27 " 4ms G2G Samsung SVA @ 144Hz (Over Drive = Normal)



27 " 1ms G2G AU Optronics TN Film @ 144Hz (Response Time = Normal)





27 " 1ms G2G AU Optronics TN Film @ 144Hz (OD = Normal)



27 " 4ms G2G AU Optronics AHVA (IPS-type) @ 144Hz (OD = Normal)



27 " 4ms G2G AU Optronics AHVA (IPS-type) @ 144Hz (OD = Normal)

We can compare the Z271 to some of the other gaming 27" models we've tested. The popular fast TN Film models like the Dell S2716DG and Asus ROG Swift PG278Q show smoother motion with less noticeable blur, as their response times are faster than the VA panel of the Z271. They do show moderate levels of overshoot though so while they feel snappier, you do have to live with some dark trailing. The high refresh rate IPS-type panels in the Asus ROG Swift PG279Q and Acer Predator XB270HU are also a little faster than the Z271 and show no overshoot, so are also a bit more suited to gaming. While the Z271's VA panel can't quite keep up with these other high end gaming screens of other panel technologies, it still offers a decent performance as far as VA technology goes:



27 " 4ms G2G Samsung SVA @ 144Hz (Over Drive = Normal)



35" 4ms G2G AU Optronics AMVA @ 120Hz (OD = Normal)

We can compare the performance with another recent high refresh rate VA panel we've tested. An AU Optronics panel with a native 144Hz refresh rate, overclocked to 200Hz in fact by Acer in their Predator Z35. That model showed slower overall response times, including some very slow transitions from black to grey, and struggled with refresh rates above 120Hz in practice. The Samsung VA panel used here in the Z271 is certainly a good step in the right direction and could keep up with the 144Hz refresh rate demands without much problem, and showed faster and sharper moving images than the Z35 had.





Additional Gaming Features

Aspect Ratio Control - the Z271 has 2 options for aspect ratio control through the OSD 'system' menu as shown above. There are options for 'aspect' and '1:1' only, but that should cover most real scenarios. The screen is natively 16:9 so will be well suited to a lot of external devices, games consoles and DVD players anyway. The other modes will allow you to support other unusual aspect ratios like 5:4 or 4:3 without issue.

Preset Modes - There are three specific game preset modes available from the 'modes' menu. There are modes for Action, Racing and Sports to choose from. All have differing preset values but you can also save your own settings in to each mode if you want, to set up the screen how you like for different gaming needs. You'll probably at least want to turn down the Over Drive setting which is set as "extreme" in some cases!

Refresh rate num - You can enable a setting if you want which will display your active refresh rate in the top corner of the screen.

Dark Boost - You can adjust this slider to change the black saturation levels in dark images, to help bring out detail in darker scenes. Might be useful if you play a lot of darker games although the black depth and contrast ratio is also a strong point of this VA panel.





Lag

We have written an in depth article about input lag and the various measurement techniques which are used to evaluate this aspect of a display. It's important to first of all understand the different methods available and also what this lag means to you as an end-user. Input Lag vs. Display Lag vs. Signal Processing To avoid confusion with different terminology we will refer to this section of our reviews as just "lag" from now on, as there are a few different aspects to consider, and different interpretations of the term "input lag". We will consider the following points here as much as possible. The overall "display lag" is the first, that being the delay between the image being shown on the TFT display and that being shown on a CRT. This is what many people will know as input lag and originally was the measure made to explain why the image is a little behind when using a CRT. The older stopwatch based methods were the common way to measure this in the past, but through advanced studies have been shown to be quite inaccurate. As a result, more advanced tools like SMTT provide a method to measure that delay between a TFT and CRT while removing the inaccuracies of older stopwatch methods. In reality that lag / delay is caused by a combination of two things - the signal processing delay caused by the TFT electronics / scaler, and the response time of the pixels themselves. Most "input lag" measurements over the years have always been based on the overall display lag (signal processing + response time) and indeed the SMTT tool is based on this visual difference between a CRT and TFT and so measures the overall display lag. In practice the signal processing is the element which gives the feel of lag to the user, and the response time of course can impact blurring, and overall image quality in moving scenes. As people become more aware of lag as a possible issue, we are of course keen to try and understand the split between the two as much as possible to give a complete picture. The signal processing element within that is quite hard to identify without extremely high end equipment and very complicated methods. In fact the studies by Thomas Thiemann which really kicked this whole thing off were based on equipment worth >100,1000 Euro, requiring extremely high bandwidths and very complicated methods to trigger the correct behaviour and accurately measure the signal processing on its own. Other techniques which are being used since are not conducted by Thomas (he is a freelance writer) or based on this equipment or technique, and may also be subject to other errors or inaccuracies based on our conversations with him since. It's very hard as a result to produce a technique which will measure just the signal processing on its own unfortunately. Many measurement techniques are also not explained and so it is important to try and get a picture from various sources if possible to make an informed judgement about a display overall. For our tests we will continue to use the SMTT tool to measure the overall "display lag". From there we can use our oscilloscope system to measure the response time across a wide range of grey to grey (G2G) transitions as recorded in our response time tests. Since SMTT will not include the full response time within its measurements, after speaking with Thomas further about the situation we will subtract half of the average G2G response time from the total display lag. This should allow us to give a good estimation of how much of the overall lag is attributable to the signal processing element on its own. Lag Classification

To help in this section we will also introduce a broader classification system for these results to help categorise each screen as one of the following levels: Class 1) Less than 16ms / 1 frame lag - should be fine for gamers, even at high levels

Class 2) A lag of 16 - 32ms / One to two frames - moderate lag but should be fine for many gamers. Caution advised for serious gaming and FPS

Class 3) A lag of more than 32ms / more than 2 frames - Some noticeable lag in daily usage, not suitable for high end gaming





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.

(Measurements in ms) Total Display Lag (SMTT 2) 6.71 Pixel Response Time Element 3.30 Estimated Signal Processing Lag 3.41 Lag Classification 1 Class 1

We have provided a comparison above against other models we have tested to give an indication between screens. The screens tested 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 screen showed a total average display lag of only 6.71 ms as measured with SMTT 2. Taking into account half the average G2G response time at 3.3ms, we can estimate that there is ~3.41ms of signal processing lag on this screen which is basically nothing. This is fairly typical result from a G-sync screen and there are no issues here at all for gaming.





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, leaving small 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 interfaces support HDCP for any encrypted and protected content

Fairly limited range of connectivity options provided with only DisplayPort and 1x HDMI offered. Although at least there is HDMI for connection of an external device if you want.

Cables provided in the box for DisplayPort only.

Light AG coating providing clean and clear images, without the unwanted reflections of a glossy solution.

Wide brightness range adjustment possible from the display, including a maximum luminance of ~339 cd/m 2 and a decent minimum luminance of 29 cd/m 2 . This should afford you good control for different lighting conditions. Contrast ratio remains stable across that adjustment range as well and is excellent thanks to the VA panel. Brightness regulation is controlled without the need for PWM and so is flicker free for all brightness settings.

Black depth and contrast ratio are excellent thanks to the VA panel at 2529:1 after calibration. Detail in darker scenes should still not be lost as a result.

There is a specific 'movie' preset mode available for movies or video if you want which doesn't look that dissimilar to our calibrated custom mode, other than the brightness being at 77%. Might be useful if you want a brighter mode for movies, but you can't change any settings without it reverting back to the user mode again so it's fairly useless we felt.

Good pixel responsiveness which should be able to handle fast moving scenes in movies without issue. At 60Hz (which would be used certainly for external devices) there is no overshoot in the 'normal' Over Drive mode.

Pretty wide viewing angles thanks to the VA panel technology meaning several people should be able view the screen at once comfortable and from a whole host of different angles. The viewing angles are not as wide as IPS and you do start to see some washing out of the image if you're viewing from too wide an angle.

Some pale blue glow on dark content from an angle, but not as noticeable as typical IPS glow.

Good and easy to use ergonomic adjustments available from the stand, making it easy to reposition the screen for viewing if needed.

No noticeable backlight leakage, and none from the edges which is good. This type of leakage may prove an issue when watching movies where black borders are present but it is not a problem here.

2x 7W integrated stereo speakers on this model. There is also an audio output connection for headphones if needed.

Decent range of hardware aspect ratio options including 'aspect' and a 1:1 pixel mapping mode.

Picture in picture (PiP) and Picture By Picture (PbP) are not available on this screen.





Conclusion

The Z271 delivered a lot of what we expected from a VA panel, and actually a little more. This panel technology is characterised by its strong contrast ratio and deep blacks, which it delivered - well beyond the Acer 1000:1 spec in fact. A lot of people like VA panels since they are not subject to the white glow that IPS panels are, and the viewing angle performance of the panel here was again pretty typical for VA. Somewhere between IPS and TN Film, but as expected. We were impressed though with the noticeable steps forward Samsung have managed to make with VA response times. This has always been a weak point of VA tech, but Samsung have done a nice job boosting pixel transitions, along with the increased native refresh rate of 144Hz. It's not quite as fast as IPS and TN Film gaming screens, but it offers a decent gaming option in the VA space. Overshoot is minimal and the G-sync support and wide refresh rate range helps make this well suited to a large audience and varying system capabilities. Input lag was also very low, as we had expected given the presence of the G-sync module. We were disappointed that ULMB wasn't included, as there's no real reason why it couldn't be given response times were adequate to support the refresh rate.

In other areas the default setup of the screen was good, and it offered a nice range of easy to use stand adjustments and some nice extras like the USB hub, speakers and ambient light system. The 1080p resolution felt limited for day to day desktop use, having used so many high res screens in recent times. However, some people will still be fine with this resolution and screen size, and it's certainly less demanding on your system and graphics cards when it comes to gaming at high refresh rates. One to be wary of. Overall we felt this was a good outing from VA tech with some obvious improvements in response times and gaming performance which can only be a good thing.

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Pros Cons Strong contrast ratio and black depth thanks to VA panel Missing ULMB blur reduction mode Decent response times, high refresh rate, G-sync support and low lag make it a good VA gaming option 1920 x 1080 resolution is limited for general use outside of gaming on a screen this size Good default setup and overall performance VA not quite as fast for gaming as IPS and TN Film options