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August 31, 2011

Yes, PLS

Long, long, long awaited model from Samsung is now in front of you.
New PLS technology (Plane-to-Line Switching) has been developed by Samsung as an answer to growing popularity of IPS panels (In-Plane Switching) made by LG.

Is PLS a revolution?
How does it look next to its competitors?
Is it much different from Samsung older technology (PVA)?
How does it perform in various tasks as a multimedia monitor?
What about LCD glow and crystalline effect?
Tons of questions.

No review is valid unless a reference monitor is used to compare and validate observations and measurements.
This unit has been tested next to NEC 2490WUXi (H-IPS with A-TW polarizer, standard color gamut, CCFL backlight) as a reference monitor with LaCie Blue Eye Pro / SpectraView II / Eye One Display 2 calibration kits.
Other technologies used for comparisons: CRT, TN (standard gamut, LED BL), S-PVA (wide gamut, CCFL BL).

You are invited to go through this thorough review and decide if this monitor is right for you.
This review may help you find what you have been looking for or ... save you $$$.

The Samsung S24A859DW features 24" PLS white LED backlight panel with 1920x1200 resolution built in a simple elegant silhouette (LTM240CL01 PLS WUXGA 1920 1200 according to Samsung).
Advanced mechanics and ergonomics?
Yes, you get it.

From the Manual:

The Samsung S24A850WD is almost a perfect product as far as mechanics is concerned.
One exception.
The panel does not go all the way down to the level of the stand base leaving some 3.5 in (9 cm) space over the desk level.
It would have been OK if a sound bar speakers were planned to be attached underneath.

How to place a monitor with limited height adjustment.
Scope of Supply

The Samsung S24A859DW arrived in a box (15 lb / 6.8 kg) that can be described as "the most economical" package for a 24" monitor.

In the box:

1. Samsung S24A859DW
2. Stand base
3. External power adapter
4. Power cable
5. D-SUB cable
6. USB 3.0 cable
7. Papers
8. CD:

Neither DVI cable nor DP cable were included.
Samsung says that components may differ in different locations.
How Glossy is Semi-Glossy?

The Samsung was expected to have semi-glossy panel.

Matte finish introduces so-called "crystalline effect" on LCD monitors - subtle sparkly, frosty haze on static massive white backgrounds.

Is it subtle?
Yes, it is.
Do all users pay attention to it?
No. Most of them have no idea about crystalline effect.
Do all matte panels have crystalline effect?
Yes, they do.
Do glossy panel have crystalline effect?
No, they don't.
Does it affect photos, movies, games?
Not at all.
What may it affect?
Reading from a monitor (text work, internet browsing).
What will happen if a matte panel loses crystalline effect?
The panel will become glossy.
Is it better to have no crystalline effect?
Yes, of course.
Do all matte panels have the same amount of crystalline effect?
No, it differs.

For inexplicable reasons current matte IPS panels have a "stronger" crystalline effect.
Typical PVA or TN panel would have it to a lesser degree (mild).
The reference IPS monitor NEC2490WUXi is known to have matte panel finish with mild crystalline effect. But this is an exception.

The Samsung S24A850DW is a winner here.
Its surface is matte just enough to prevent glare. Crystalline effect is minimal. It is less than on any other monitor in this test.
Manufacturing Quality

Materials: very good.
Assembly quality in general (except panel): there is no trace of complant.
Panel backlihgt uniformity: unacceptable.

Controls and OSD

The Samsung S24A850DW has quite extensive OSD (Menu).
By no means I would call it intuitive: too many steps and cliks are necessary to reach a desirable setting.

Once OSD is activated, arrows appear on the screen to help you navigate the entire menu. That is a great help.
We will come back to OSD later in the review.

Image Quality

Viewing angles (must be: image stability is not affected by viewing angle change) is a single most important characteristic of LCD monitors.
This is a key factor that influences image quality for LCD monitors.


PLS viewing angles: excellent and identical to IPS. Colors are stable from a wide range of horizontal angles. PLS demonstrated a bit less decrease in brightness (vs H-IPS) from sharp angle views.
LCD glow can be seen from diagonal views.
It's not an issue for a regular position in front of the monitor.

PLS next to an older Samsung product - S-PVA: no colorshift on PLS, no false 3D effect, no colors wash out from angle views, no "green frame" flicker.

Colors on the Samsung S24A850DW: in most cases - realistic skin tones, no dithering anywhere (Lagom and other tests), no red faces unlike those on wide gamut S-PVA next to it.
No color tint on white noted.
However colors near solid blue are too intense on the test unit. It was compared with all participating monitors. Even WG S-PVA did not go that far.

Subjectively from the first approach: the Samsung S24A850DW does look and behave as an IPS monitor with sRGB-like gamut, somewhat unbalanced colors, very convincing black and contrast.

Now we are going to watch two video clips.
Yes, it is about the Samsung SA850 24" on PLS.
The first one is PLS vs H-IPS vs S-PVA technologies shootout.
You would not forgive me if I don't show these videos to you.
All monitors are set to the same brightness level(brightness of white). So actual black levels are different according to different contrast ratios.
Unfortunately our hero does not look most favorably in some episodes.
Please don't get panic.
You will see how LCD glow behaves on different panels, but remember that we don't buy monitors to stare at empty black screens from diagonal angle in darkness.
Also note how each black screen changes with angle.

The second video is devoted to Samsung products: PLS vs S-PVA.
Please pay a special attention to horizontal angles.
Are black bars good or not so good? And what about the picture between them (contrast, colors...) on two monitors?

Results speak for themselves: very good.
Black goes as low as 0.1 cd/m2
Measured contrast ratio ~800:1 is very good and stable within the whole range of brightness.

Even more.
The Samsung S24A850DW features autobrightness sensor ("Eco Light Sensor") which adjusts the screen brightness depending on ambient light intensity.

In Eco mode the screen brightness went as low as 34.8 cd/m2 (white) and 0.045 cd/m2 (black) with the same stable CR 773:1

And what about "Dynamic" CR?
It does not have a physical sense and does not exist in nature.
So we cannot measure anything that does not exist.
We measure "Static" CR.
However the most important CR is "Display CR" - this is what we actually see on the monitor. Display CR is hard to measure and function of viewing angles. This is why good viewing angles are so important.
In this video you can see again how quickly CR changes with angles. What you see is display CR.

"Dynamic" CR is a marketing gimmick, a trick with numbers to impress naive consumers.
You can see those numbers in specs. Remember: it is nothing.

Brightness distribution
By default picture mode is Custom.
We use this mode for measurements and calibration.
This the most useful, realistic, "all purpose" mode.

As usual several picture presets are found in the menu.

And as usual, those presets do nothing but spoil the picture.
Standard and Game modes are just placebos that boost brightness to "preset" numbers (in cd/m2: W=240/B=0.3 and blinding W=365/B=0.5 respectively) with minimal effect on other parameters.
Cinema simply kills the picture sending colors way off.

"Dynamic" CR does not exist. But a particular combination of settings that is referred to in the menu as "Dynamic Contrast" - does exist.
This mode makes bright scenes brighter and dark scenes darker.
The way electronics determine what is bright and what is dark, and when it's time "to switch the light off" can lead to embarrassing results.
A real example from the test.
In a movie scene, a few men in dark suits enter the room.
Technically it means more %% of black color. "Dynamic contrast" reads this change as a "darker scene" and .... yes, turns the light down!
This mode acts like unwanted movie editor.
Try to use it for fun.
Calibration Results: Before and After

First of all let us look at color gamut triangle.
The monitor's gamut covers sRGB space almost completely, but extends outside sRGB in the red and especially in the blue areas.
Ideally both triangles must be identical (1:1 match).

The probe marks the blue color as a violator #1.

The "after calibration" diagram looks like second to perfect.

Grey scale tones in Lagom test (1-255) are distinguishable from 2 to 254.
Despite this glowing calibration report visually solid blue color remains too intense (compared with a white LED and a wide gamut monitors).
This observation along with the monitor's color gamut configuration (easily detected by the probe) is a bit alarming. This issue is beyond calibration equipment. It is entirely on monitor's electronics.

We compared Samsung SA850 color gamut with WG monitors.
Please look at color gamut diagrams below and identify color exterema for each monitor in red, green and blue colors (respective triangles corners).
The Dell 2408 and even the discontinued color gamut record breaker Samsung XL20 did not go so far in the blue color as the Samsung SA850 did.

So far the Samsung S24A850DW seems to be only "conditionally" sRGB monitor.
Pixel Structure & Fonts

As was mentioned above, the Samsung S24A850DW on PLS has a semi-glossy panel with minimal crystalline effect.

This is what was noted in comparison with H-IPS panel.
Pixel structure looks very similar on PLS and H-IPS: accurate rectangles.
You can see a bit more "sparkly" background on H-IPS vs more transparent coating on PLS.
But the font itself looks a bit more accurate on... "less glossy" H-IPS.
Some more solid color components (esp. darker blue) makes letters on PLS a bit "fuller" and less sharp than on H-IPS.
A similar effect has been observed many times on wide gamut monitors with inadequate electronics.
Sharpness control (between default 60 and maximum 100) produces zero effect on text sharpness.
Again, do not panic. We are splitting hairs when compare PLS with IPS.
Inter-pixel grid on PLS looks a bit less visible than on H-IPS. This may be an explanation for a subtle difference in brightness at sharp angles (in favour of PLS).

Below is comparison of PLS with older Samsung's technology S-PVA.
You can see a striking difference. This is a typical S-PVA effect: unevenly lit pixels make letters slightly fuzzy.


Nothing major to speak about.


Measured input lag vs CRT ~9-10 ms

Video: Samsung SA850 24" PLS vs 24"TN

The Samsung S24A850DW features three settings for "response time".
By default it is "Faster".

Perception of "ghosting" effects is subjective.
Various tests give only rough approximation to what can be expected.
This test is not an exception.
At least you can see the difference between three "response time" settings of the Samsung S24A850DW.

Subjectively blur around moving objects in tests on PLS (Faster) is identical to the NEC 2490WUXi and much less than on S-PVA.

The Samsung S24A850DW offers three screen formats to choose from.

The monitor accepted 60/50Hz (both progressive and interlaced) video signals from an external BD player.
24Hz signal sent the testing unit into a sleep mode.

Playing with "Magic Color".
This mode drops color temperature by about 700-800K without a notable effect on other parameters.

Blu-ray: Casino Royale
Video playback on the Samsung S24A850DW is as smooth as one can expect from an LCD monitor.
No tearing, no ghosting.
IPS-like colors and clarity.
LCD glow effect will not be an issue unless you watch movies in dark environment from diagonal angles.

DVD: And now...Ladies & Gentlemen
DVD: Desperado
Blu-ray: Casino Royale
A dark scene. Disregard some photocamera noise.
Blu-ray: Casino Royale
Blu-ray: MIB
Blu-ray: Casino Royale
Final Thoughts

The Samsung SA850 24" (27") is probably the most interesting LCD monitor ever made by Samsung.
The monitor leaves you with an impression of thoroughly designed consumer oriented product.
Is it a revolution?
For the consumer market it is not. It will be accepted there as another derivative of IPS technology.

For Samsung this model is a big step forward.
The Samsung SA850 with PLS panel is designed to offer exactly what many prospective consumers have been looking for:
generous size and resolution
excellent viewing angles
sRGB color gamut
stable colors and contrast ratio
semi-glossy panel for comfortable reading
advanced mechanics and ergonomics
elegant design
wide range of brightness regulation without noticeable flicker
multi-task universal monitor
reasonable price

Unfortunately the test unit does not fill this challenging list completely
1. Backlihgt uniformity is unacceptable
2. sRGB mismatch does not seem to be supported by appropriate electronics and factory settings
3. The monitor is not fully height adjustable (3 more inches!)
4. Optional attachable sound bar speakers would complete the monitor's application for multimedia status

#3 and #4 are optional
#1 is an imperative
#2 is something to be reviewed more closely

Fixing at least #1 and #2 would make the Samsung S24A850DW a monitor of choice for "up to $600" sector.
And that will be a revolution.

List of recommended monitors

NEC PA301w (overall best available monitor; not ideal for text work due to matte screen effect)
Dell U3011 (if 30" is necessary but no money for NEC PA301w; not perfect color rendering related to wide color gamut; not ideal for text work due to matte screen effect)

Apple Cinema (limited connectivity, ergonomics, mechanics)
Samsung S27A850DW (not perfect color rendering related to sRGB color space mismatch)

24" (best models)
NEC P241w (not ideal for text work due to matte screen effect)
NEC PA241w (not ideal for text work due to matte screen effect)

24" (medium price)
Samsung S24A850DW (not perfect color rendering related to sRGB color space mismatch)

24" (budget)
Dell U2412 (not ideal for text work due to matte screen effect)

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