If dividing by 0.84 seems to complex, here’s an easier approach. Assume one foot of distance for every ten inches of screen size. Look at the table below (based on the 0.84 formula) and you’ll it’s a very close approximation.
Not everyone agrees with THX’s numbers. The speaker manufacturer Aperion Audio recommends that you not sit closer than six and a half feet from a 50-inch 1080p set. Aperion also recommends you sit no farther than 9 feet 9 inches for the best experience.
Home theater blogger Carlton Bale developed an Excel spreadsheet for calculating optimum distances depending on various criteria. This busy, small-print table can be intimidating at first glance. But it’s not that difficult if you have a 1080p HDTV. Enter the size of your screen in cell C8. You’ll find various suggested viewing distances from row 31 to 35, with the easy-to-read numbers in column E. For instance, for the “SMPTE Longest Recommended viewing distance,” see cell E32. If you’re not sure what “SMPTE Longest Recommended viewing distance” means, hover over the label for a longer description.
I might add that Bale’s “Shortest recommended viewing distance” is an absurdly short 2.6 feet for a 50-inch TV. A footnote explains that this is based on peripheral vision, not pixel size.
As a test, I sat almost that close—39 inches—to my 1080p, 50-inch TV and watched a few scenes from large-format, immersive movies I own on Blu-ray. The pixels were annoyingly visible—especially in bright scenes.
That hasn’t that bothered me in movie theaters, even when I’m sitting in the front row and the theater has only a 2K projector (with a resolution almost identical to 1080p). Eric Gemmer, Director of Imaging Technology at THX, explained why. “When you look at a TV,” he said, “pixel boundaries are set; they’re very solid…. On a projected screen, they’re smeared a little bit.” This smearing is more pronounced in a commercial theater, where the screen is perforated to let out sound from the speakers behind the screen.
4K TVs remove issues—and create new ones
The advantages of 4K TVs isn’t always obvious. According to Carton Bale, “To be able to detect the additional resolution…the screen must be quite large and you must sit fairly close.”
But the major point is that you can sit much closer. If you must sit five feet from your HDTV to not see pixels, you can cut that distance in half and sit 2.5 feet away with a 4K set of the same size. But at that distance, other problems take over. As THX’s Gemmer put it, “Pixels aren’t the problem now.”
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