Three, the same snapshot illustrates another peculiarity of the angles the manufacturers specify. They usually declare a total angle to both sides from the normal (for the vertical angle – the above and below angles are summed up), while for this monitor (and for all TN+Film matrices for that matter) the above angle is much bigger than the below angle, and there’s a different artifact there – when you are looking at the screen from above, the bottom of the image first fades out and then, at a bigger angle, becomes inverted (white acquires a characteristic bluish tincture and becomes darker than light-gray shades). As a result, we have a big vertical viewing angle in the specification, but the top of the onscreen image becomes dark on even the slightest deflection of the monitor’s screen backwards.
Four, there’s the same story with the viewing angles as with the response time which is measured on black-to-white and white-to-black transitions only. The manufacturer specifies the contrast you see when your line of sight is perpendicular to the screen plane and says at which angles this contrast ratio drops down to 10:1, but you don’t know anything about how this contrast ratio is changing within these two points. The graph below shows the dependence of the contrast ratio on the angle of view for two different matrices (this is a purely theoretical example, not a result of any measurements – for illustrative purposes only):
As you see, matrices with such curves will have identical specifications: the maximum contrast ratio is 400:1, the viewing angles (as measured by the contrast drop to 10:1) equals 160 degrees (80 degrees into either side). However, if you look at the matrices at an angle of 40 degrees, one will have twice more contrast than the other; in other words, the user of one matrix will have wider viewing angles than the other, although the specs of the two matrices are perfectly identical.
Five, it is only the reduction of the contrast ratio that’s considered when measuring the viewing angles – distortions of color reproduction are not counted in. For example, here’s a snapshot of the Greenwood LC521FT monitor with a purely white background onscreen:
As you see, white color is darker when viewed from a side, but it also acquires a strong yellow-brown coloring. Sometimes such a change of the color may be more visible than a change in the contrast, but the manufacturer doesn’t count that in.
Six and the last, the manufacturers declare only vertical and horizontal viewing angles, whereas you may want to look at the screen from the right and above, for example. The following chart shows the dependence of the contrast ratio on both viewing angles (courtesy of Fujitsu):
Thus, it turns out that vertical and horizontal viewing angles are the maximum ones, and they are put into the specs, while “diagonal” viewing angles are much smaller.
So, the item in an LCD monitor’s specification called “viewing angles” does not actually say much about what you’ll see on the screen of this monitor. Moreover, it involves so many reservations and depends on the particular matrix type that an extensive investigation is required to objectively evaluate the real viewing angles, so the only practical way for the user is the following: do not trust blindly to the specification, but examine the monitor models you’re interested in with your own eyes.