Many have heard about the effect of the TV screen on the human organs of vision. Surely any person from childhood remembers the instructions of their parents – “do not sit close to the TV – you will ruin your eyes.” Indeed, if you do not adhere to a certain distance from the screen of the eye, to cover the entire image, they begin to “rush” from side to side. This leads to excessive strain of vision, spasm of the lens and in the future threatens the development of myopia. In addition, when watching television programs closely, the bright light of the image also begins to appear, whose spectrum also does not affect the eyes in the best way.
In recent years, the problem of properly placing the TV in the room has been complicated by some new circumstances. On the one hand, TVs with very large values of the screen diagonal are widespread – at an affordable price it is quite possible to purchase such a device with a diagonal of more than a meter. When such a television is located in a relatively small room, the same effect is actually observed as when closely viewing a standard small screen – the eyes are not able to capture the entire image at once and are actively moving. For this reason, many people after acquiring a home theater begin to complain of headaches during long viewing.
On the other hand, an important factor was the resolution of the television “picture”. For example, a conventional analog television signal gives an image of 720 by 526 pixels, so when such an image is displayed on a large screen when viewed closely, it will consist of visible pixels, which complicates the viewing and additionally tires your eyesight. A digital signal and video recording on DVD gives the best values (up to 1920 by 1080 pixels), which is more favorable for the eyes when watching TV with a large screen diagonal.
So how is it better to choose the diagonal of the TV , taking into account the size of a particular room? Some publications even created tables between the screen size and the area of the room, but this is not quite the right approach – the room can have a different configuration, be square or elongated with the same area, and the distance to the TV screen in this case depends on its location in the room. It is much easier to choose the distance depending on the specific size of the TV diagonal and image quality on it.
For example, if you take into account only the diagonal of the screen , with a diagonal size of 32 inches, the TV should stand no closer than 2.5 meters, with 40 inches – 3 meters, 50 inches – 4 meters and so on. However, if you watch a low-resolution TV show at such a distance, your eyes will still strain, trying to fit disparate pixels into a single picture in your head. Therefore, if you plan to use the TV only for viewing an analog television signal, the empirical method will help to determine the optimal distance to it – a hand is extended towards the screen and covers it with the palm of your hand. The optimal distance will be where the visual dimensions of the palm and screen coincide (the hand completely covers the screen). At such a distance, even all inaccuracies in the analog image will be erased and therefore will be relatively invisible to the eyes.
At a higher resolution, a closer arrangement of the TV screen relative to the audience is allowed. So, with HD resolution (1366 by 768 pixels), this distance is about one and a half times less than calculated by the empirical method. And with FullHD resolution (1920 by 1080 pixels), it is about half the distance with analog resolution. It is important only in this case to correctly adjust the brightness of the screen – with such close viewing, the main negative factor of the TV screen on the organs of vision is precisely the radiation spectrum.
We must not forget that in order to view harmful not only close, but too far away location of the screen that can be observed, for example, when using a television with a small screen sizes in the large hall. At the same time, the eyes are strained, trying to see the details of the image, and such a prolonged overstrain is fraught with various forms of blurred vision.