TV Viewing Distance and Screen Placement in the Home Theater
The most favorable TV screen size is directly correlated with the available watching distance. Conversely, there are additional factors also that has to be taken into account.
Viewing Distance: Is it simply a matter of individual preference?
Take a seat excessively close to your huge screen TV and you’d be able to visualize the picture build-up structure – scanning lines or pixels figuring the image, thus sidetracking your mind and trashing your home theater experience. However, be seated too distant, and the impact would be gone.
The certainty is that there aren’t any systematic rules here. This doesn’t imply that there aren’t any guidelines that you have to adhere to when preparing for a big screen purchase or a would-be home theater area.
SMPTE Recommendations and the THX Certification standards:
The Society of Motion Pictures and Television Engineers (SMPTE) suggests that the screen size for home theater use needs to take up a 30 degrees area of view – in the horizontal arrangement – for the spectators. Alternatively, the perfect TV viewing distance should be such that the screen width uses an angle of 30 degrees from the watching spot.
This SMPTE principle is also in proportion to the THX certification principles in that these mention that the back row of seats has to have at least a 26 degrees viewing angle and while commending a best possible viewing angle of 36 degrees.
So How Does All This Translate In Practical Terms?
A general rule for the television viewing distance according to the SMPTE and visual acuity principles, is that the closest television watching distance between you and your big screen television must be limited to around twice the screen width (more specific 1.87 x screen width for a subtended angle of 30 degrees), while the furthest distance being not exceeding five times the width of your screen.
But, it is additionally vital to realize that these maximum and tiniest viewing distances need to be perceived in the light of the video signal definition.
A totally resolved high definition television (1080i, 1920×1080) supports a closer watching distance than regular analog TV. While double the screen width would be the ultimate TV viewing distance for a HDTV display, it will be a bit too close for ordinary TV; in the later case, a three times the screen width will be a better option.
When it speaking about the use of regular-size standard definition analog TVs in the home theater, i.e. about 36 / 40 diagonal, the most favorable viewing distance range is between 8 feet and 12 feet. TV sets lesser than 36-inches aren’t big enough to be eligible for Home Theater use because their smaller screen size will not give the expected impression on the watcher.
Vertical Angle of View & Screen Height:
For optimal viewing, the eyes of the viewer needs to be even with the midpoint of the screen.
Maximum vertical angle of view: In those home theater set-ups where this is not feasible, the SMPTE guidelines propose that the maximum vertical angle computed at the seated eye height from the front row middle position to the top most part of the projected image should not exceed 35 degrees.
This does not stand for the optimum viewing angle but rather the threshold beyond which the viewer will be subjected to an intensified neck tension.
Minimum angle of vision: While there don’t appear to be any specific SMPTE or THX guidelines in this respect, studies have presented that if the screen size occupies under 15 degrees of the watcher’s vertical field of view, then that image looks as if it were tiny.
Practical Concerns:
In a normal home theater set-up, you do not have to really be anxious about neither the maximum vertical angle of view, nor regarding the least possible vertical angle of vision for an effective movie theater experience.
If one were to adhere to the proposed television viewing distance of twofold the screen width (as further particularized above based on the SMPTE principle of 30 degrees horizontal field of vision), you would necessarily be obeying the minimum angle of vision. The reason behind that is there’s a set relationship between screen height and width in conformity your home theater screen aspect ratio of either 16:9 or 4:3.
Taking into account that a good number of home theater rooms are approximately 10 feet (3m) high, the resulting vertical viewing angle is normal well within the maximum of 35 degrees detailed in the SMPTE guidelines, all you have to do is simply stay within the twofold the screen width guideline for your viewing distance.
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