Q. I read your article about how you should sit really close to a 4K TV because the resolution is so high. But is that really true? You say you should sit just three feet away from a 55-inch set! I think you have your math messed up. — Quinn, Santa Fe, New Mexico
Quinn, you are referring to my September 19, 2018 article, “4K TV: How Far Away Should You Sit?” In the article, I explain that you do have to sit closer to a 4K set than a HDTV to truly see the increased number of pixels on the 4K screen. The extra pixels allow the 4K TV to deliver four times the resolution of a high-def set.
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I also note in the article that Sony recommends that you sit 1.5 times the vertical inches of a 4K TV. For example, Sony says you should sit around 3 to 3.5 feet away from a 55-inch 4K TV while you should sit around 4 to 4.5 feet away from a 65-inch set. (See Sony’s web page on how close you should sit in front of a 4K TV.)
See an update on this article.
Since my article was published, several readers have sent me e-mails or posted comments here that say I have no idea how to do a math calculation. They are incredulous that anyone should have to sit just three feet in front of a TV.
“This guy needs a math lesson,” wrote one reader.
But what these readers fail to understand is that Sony says you should multiply the ‘vertical inches’ of the TV by 1.5, not the diagonal or horizontal inches. (I say ‘vertical inches’ in the article, but I can understand how someone might think you are supposed to use 55 inches, or 65 inches, depending upon the set.)
The ‘vertical inches’ is the inches from the top to the bottom of the screen, which is considerably less than the horizontal or diagonal inches. So when you multiple the ‘vertical inches’ by 1.5, you get a smaller number, such as three feet or four feet.
So I hope that clarifies the matter. And if you still don’t think you need to sit that close to a 4K TV, I’ll sum up by quoting from Sony’s web page on 4K TV:
“The recommended distance when viewing a video or a program from a 4K TV is 1.5 times of the TV vertical screen size,” Sony says. “The naked eye can’t differentiate individual pixels when watching a 4K TV from this distance. This means that pixels effectively disappear when viewing 4K images. Thus, creating an impression of watching the image with the same detail and resolution as real life.”
Happy viewing!
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Respectfully, I would like to differ from Sony’s recommendations. It is almost as if Sony’s engineers made a factor of 2 error which is a common error when one converts acuity because we are resolving 2 pixels. Resolving 2 pixels means we can see that there are 2 distinct pixels rather than just 1. Using Wikipedia, 20/20 human vision corresponds to “0.94 arc minutes per line pair (one white and one black line)”. So, in order to calculate a human’s ability to resolve, calculate how far away from the screen a human must sit in order to see that there is a single black pixel separating 2 white pixels.
https://en.wikipedia.org/wiki/Visual_acuity
Also, I might choose a little different phrasing in my description. From Sony’s website: ” The naked eye can’t differentiate individual pixels when watching a 4K TV from this distance. This means that pixels effectively disappear when viewing 4K images. Thus, creating an impression of watching the image with the same detail and resolution as real life. ” In essence, what Sony is saying is that a viewer would want to sit a distance such the human eye cannot resolve the TV’s individual pixels. So, I think the “recommended distance” should actually be called “minimum recommended distance” because this is the minimum distance at which the images will appear continuous rather than being composed from a collection of square pixels. If one sits closer than this, then with 20/20 vision, one can resolve pixels and the image would appear pixellated therefore undesirable. As such, I submit the following table of minimum viewing distances for a 1080 and a 2160 line TV. Like Sony’s table, I use the screen diagonal measurement.
TV screen dimensions (inches) Min Distance (ft)
Diagonal Height Width 1080 2160
42 20.6 36.6 10.1 5.1
55 27.0 47.9 13.2 6.6
65 31.9 56.7 15.6 7.8
77 37.8 67.1 18.5 9.3
Also, I have run across subjective recommendations as to screen size and viewing distances. See the link at:
https://www.practical-home-theater-guide.com/Tv-viewing-distance.html
In short, there is a recommended horizontal field of view angle from SMPTE and also min/max range of horizontal field of view angles from THX to attain its certification. Of course these recommendations customarily apply to movie theaters, but one may just as well apply them to home theaters to act as guidelines more than than absolute engineering rules for design. SMPTE recommends that the horizontal extent of the screen be 30 degrees. THX suggests that the back row be no further back than to make the screen 26 degrees wide and the front row no closer than to make the screen 36 degrees wide. It is important to remember that these recommendations are subjective judgements as to what a human observer would find the most pleasing.
TV screen dimen (inches) View Dist (ft) for Horizontal FOV
Diagonal Height Width >26° 30° <36°
42 20.6 36.6 6.6 5.7 4.7
55 27.0 47.9 8.7 7.5 6.1
65 31.9 56.7 10.2 8.8 7.3
77 37.8 67.1 12.1 10.4 8.6
THAT SURE CLEARED IT UP !
I still don’t see sitting 3 feet from the TV is going to do anything but make it very uncomfortable to watch TV.
One thing that it will do is make additional viewers keep asking you to get out of the way so they can see the picture
Sony can use any type of calculations it wants, but I can see a PERFECT picture from my couch 10 feet away.
” Sony can use any type of calculations it wants, but I can see a PERFECT picture from my couch 10 feet away. ”
As you should. That was the point, Sony’s “recommended” distance is a factor of 2 low and that distance should be labeled “minimum”. Viewing at any distance greater than the minimum should look perfect to a human with 20/20 vision.
So if a marketing guy from SONY screws up we should all follow his ill advice?
No..
Of course not ,and trying to justify it does no good for any T&E writer.
Call SONY ENGINEERING and find out why they allowed this to go public and if so ,a better explanation because this one is NOT supported by facts of logic