The optimal television screen size is directly correlated with the available viewing distance. Conversely, there are other aspects as well that must be taken into account.
Viewing Distance: Is it just an affair of individual partiality?
Sit extremely near your big screen TV and you would be able to discern the image build-up structure - scanning lines or pixels forming the picture, consequently off-putting your attention and ruining your home theater experience. Nonetheless, stay excessively far away, and the impression will be gone.
The truth is that there are no scientific rules here. This doesn’t mean that there aren’t any principles that you need to adhere to when planning a huge screen purchase or a probable home theater room.
SMPTE Recommendations and the THX Certification standards:
The Society of Motion Pictures and Television Engineers (SMPTE) commends that the screen dimension for home theater use needs to fill a 30 degrees field of view - in the horizontal map - for the spectators. On the other hand, the perfect television viewing distance ought to be such that the screen width fills an angle of 30 degrees from the watching place.
This SMPTE principle is also similar to the THX certification guidelines in that these advise that the back line of seats has to have no less than a 26 degrees watching angle and while suggesting an optimum viewing angle of 36 degrees.
So How Does All This Translate In Practical Terms?
An overall rule for the TV watching distance based on the SMPTE and visual perception guidelines, is that the nearest TV watching distance between you and your big screen television should be limited to almost two times the screen width (more accurate 1.87 x screen width for a subtended angle of 30 degrees), while the farthest distance being barely five times the width of your screen.
On the contrary, it is also critical to comprehend that these maximum and minimum watching distances have to be seen in the light of the video signal definition.
A fully resolved HD television (1080i, 1920×1080) supports a nearer viewing distance than ordinary analog TV. While twofold the screen width will be the best television watching distance for a HDTV display, it will be a bit too close for typical TV; in the later case, a three times the screen width will be a superior pick.
When it speaking about the use of regular-size standard definition analog TVs in the home theater, i.e. around 36 / 40 diagonal, the most favorable watching distance range is between 8 feet and 12 feet. television sets tinier than 36-inches aren’t big enough to meet the requirements for Home Theater use as their smaller screen dimension would not impart the wanted impact on the watcher.
Vertical Angle of View & Screen Height:
For best possible viewing, the sight of the watcher needs to be leveled with the center of the screen.
Maximum vertical angle of view: In those home theater set-ups where this is not likely, the SMPTE principles advise that the maximum vertical angle quantified at the seated eye height from the front row center location to the top most section of the projected image should not surpass 35 degrees.
This does not stand for the best possible watching angle but rather the threshold beyond which the watcher would be exposed to an intensified neck strain.
Minimum angle of vision: While there do not appear to be any specialized SMPTE or THX guidelines in this respect, studies have presented that if the screen dimension occupies less than 15 degrees of the viewer’s vertical field of view, then that picture looks miniature.
Practical Points:
In a usual home theater set-up, you do not need to actually fret concerning neither the maximum vertical angle of view, nor concerning the tiniest vertical angle of vision for an effective movie theater experience.
If one were to adhere to the mentioned TV viewing distance of twofold the screen width (as additionally listed previously according to the SMPTE principle of 30 degrees horizontal field of vision), you would necessarily be obeying the smallest possible angle of vision. The grounds behind that is there is a preset relation between screen height and width in accordance to your home theater screen aspect ratio of either 16:9 or 4:3.
Keeping in mind that most home theater rooms are almost 10 feet (3m) high, the resulting vertical viewing angle is customary well within the maximum of 35 degrees detailed in the SMPTE principles, all you must do is solely remain within the double the screen width guideline for your viewing distance.
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