What to know before buying a Flat Screen TV in India
We have an explanation here of the most important specifications of a flat screen TV which should be known to anyone planning to buy a new TV in India.
How TV size is measured
The size of a TV is measured as shown in the diagram here. Measuring a TV screen size is always done diagonally between the opposite corners of a TV screen. The diagram here demonstrates how a 42 inch TV screen is measured. Since one inch is equal to 2.54cms (centimeters), the 42 inch Metric TV size will be 107cms. Note that TV sizes are always rounded off to the nearest whole number.
When a TV is measured for screen size, the dimensions of the picture area of the TV is taken, that is only of the glass area on the TV screen. The TV frame surrounding the glass of the TV is not included.
TV watching distance
The recommended flat screen TV watching distance is at least 1.5 times the diagonal size of the TV. If for example you are watching a 42 inch or 107 cms TV, then you must be sitting and watching TV from a distance of not less than 1.5 meters from the TV screen. The resolution of the TV also has an important role to play in the best distance to watch TV. When you are watching TV you should not be able to see the net like pattern on the TV screen pixels. Since higher resolution TVs have their pixels much closer together you can sit and watch higher resolution TV from closer distances. For example if the 42 inch or 107 cms TV is only a HD Ready TV with 1280x720 pixels, then you may have to sit 2 meters from the TV in order not to see the net like TV pixel pattern. If the 107cms TV is a Full HD TV with 1920x1080 pixels, then it is OK to sit at 1.5 meters from the screen to watch Full HD TV. With a 4K ultra HD TV with a resolution of 3840x2160pixels you can watch 4K TV sitting even closer.
The TV watching distances mentioned above are the minimum. It may be more comfortable to sit a little further than these recommended viewing distances for TV.
TV Viewing Angle explained
TV Viewing Angle is explained as how far to the left or right of the TV you can watch TV from and still see a clear TV picture. The best position to watch TV is directly in front of the TV and this TV viewing angle is said to be 'zero' degrees. The further you go to either side of the TV, the viewing angle increases untill it reaches 90° when you are parallel to the TV screen. TV manufacturers specify the total viewing angle, which is the angle from the farthest left to the furthest right the TV can be viewed, as shown in the figure here. The theoretical maximum possible TV viewing angle is 180°, which is 90°+90°, beyond which the TV screen will not be visible. TV manufacturers tend to exaggerate the TV viewing angle specifications at 178° as shown in the diagram here. A more realistic figure for LED TVs would be something like 140°, that is you can sit and watch TV from an angle of 70° to either side of the LED TV. Plasma and OLED TVs have better viewing angles and you could possibly have a clear view of a Plasma or OLED TV at upto 160°, that is sitting at 80° to either side of the Plasma or OLED TV.
Best height to watch TV
The best height to watch TV is at eye level. The middle of the TV screen should be slightly lower than our eye level when watching TV as shown in the figure here. Our eyes are more comfortable looking slighlty down rather than up. For mounting TV on bedroom wall where you will be lying down and watching TV, it is better the TV is mounted higher up for more comfortable TV viewing lying down. The TV should be slightly tilted down so that your line of vision falls at 90 degrees on the TV screen.
TV aspect ratio explained
The Aspect Ratio of a TV is the ratio between the width and height of the visible area of the TV screen. HD TV has an aspect ratio of 16:9, old CRT TVs has an Aspect Ratio of 4:3. The 16:9 Aspect Ratio is what the flat screen TVs have, for example the Ful HD Pixels of 1920x1080 are exactly in the ratio of 16:9.
Many countries, including India, still transmit TV signals in the 4:3 format. When you view a normal 4:3 format movie in 16:9 format, the picture stretches sideways, making people and objects look fatter. You can correct this problem by changing the aspect ratio setting on your TV and watching it in the native 4:3 format, or for a wider view with less distortion on a 14:9 format.
The diagram here shows what a 4:3 picture looks like when viewed on 16:9 TV. The 4:3 picture does not fill the screen and two vacent areas remain on the 16:9 TV as shown. Also when a 16:9 format TV image is viewed on a 4:3 TV two vacent bars are at the bottom and top of the picture as shown in the diagram here.
When a 16:9 movie is squeezed and compressed into 4:3 format movie, people and objects look very thin. When widescreen video images are squeezed to fit a narrower aspect ratio it is called 'Anamorphic Video'. When expanded into 16:9 ratio they look normal. In order to save bandwidth while transmitting TV stations broadcast widescreen movies in the 4:3 format and the viewer can expand it into the 16:9 format and watch the movie normally.