Not aware of viewing distance recommendations differing between monitors and TV; it's the same 30°-40° of horizontal field-of-view for both, with 32° being a notable notch along the range.
This is then usually combined with the 60 PPD visual acuity quasi-myth, and so you get 1800px, 1920px, and 2400px horizontal resolutions as the bar, mapping to FHD and ~WQHD resolutions diagonal size independently. From these, one could conclude even UHD is already overkill. Note for example how a FHD monitor of exactly standard density (96 PPI, so ~23") at 32° hfov results in precisely 60 PPD. That is exactly the math working out in its intended way afaik.
At the same time, Mac users will routinely bring up the Pro Display XDR and how they think it is the bare minimum and everything else is rubbish (*), with it coming in at a staggering ~200 PPD, 188 PPD, and ~150 PPD at 30°, 32°, and 40° hfov respectively. Whether the integer result at 32° is just the work of the winds, who knows. It is nonetheless a solid 3x the density that was touted so fine, you would "not be able to see the individual pixels". But if that was a lie back then...
The pixel density (PPI, PPD), viewing distance, and screen real estate discussion is not one with a satisfying end to it I'm afraid. Just a whole lot of numerology, some of which I sadly cannot help but contribute to myself.
(*) not a reliable narration of these sentiments necessarily
> Not aware of viewing distance recommendations differing between monitors and TV
Uh.. what?
You usually sit 60cm from your monitor, but 3-6m from your TV. It completely changes the math, which lets you "cheat" with ordinary TV sizes (50"-65") because you will not or barely notice the difference between 1080p and 2160p.
The other way around, your monitor won't really get the 'retina' effect of not discerning pixels until you hit ~220 PPI.
> 3-6m from your TV (...) lets you "cheat" with ordinary TV sizes (50"-65") because you will not or barely notice the difference between 1080p and 2160p.
Yes, at those sizes and distances, all the usual rules of thumb will report that the difference will be indistinguishable between FHD and UHD. We're in agreement there.
It's just that if "cinematic immersion" is among the goals at all, I really don't think e.g. viewing a 50" TV from 6 meters away can provide it. That's more like "something is making noise while I'm having a pop and scrolling social media on my phone" at best. A lot of TV watching happens like that, but then resolution is rarely a concern during those anyways.
> You usually sit 60cm from your monitor
> the 'retina' effect
So we're selecting for 60 PPD ("retina") at 60 cm of viewing distance, let's see:
21" -> 42.352° hfov, 2544 × 1431, ~139 PPI. At UHD, it's ~210 PPI. WQHD would be enough though, and that'd be ~140 PPI.
All of this is to say, I have no idea where you're pulling that ~220 PPI figure from, especially when it comes to higher sizes.
You can also see the PPI slowly descending from some maximum value (eventually reaching 0) since we're talking about a flat panel, and so the math slowly gives out. If you assume a curved display and make the viewing distance the curvature radius (600R) to compensate, you can calculate that maximum value to be ~145.5 PPI. In that case, this value would remain fixed no matter the diagonal size. Not anywhere close to 220 PPI still however.
That said, I definitely sit further than 60 cm too.
> That said, I definitely sit further than 60 cm too.
I've tried sitting closer than 1 metre / (3ft) from a flat 32" 4K display, and I find it kind of overwhelming. At 60cm viewing distance I end basically up keeping one window down the middle of the display that is in focus, and put utility windows off to the sides - and then I physically translate my head to look at then, because the corners of the screen are distorted if I just pivot.
I used to have a 40" 4K display, back when such things were available on eBay from SK, and I had to wall mount it some ways behind the back of my desk to use it comfortably.
I'm sure a curved panel would help with the corner distortion up close, but it kind of seems like a solution in search of a problem.
This is then usually combined with the 60 PPD visual acuity quasi-myth, and so you get 1800px, 1920px, and 2400px horizontal resolutions as the bar, mapping to FHD and ~WQHD resolutions diagonal size independently. From these, one could conclude even UHD is already overkill. Note for example how a FHD monitor of exactly standard density (96 PPI, so ~23") at 32° hfov results in precisely 60 PPD. That is exactly the math working out in its intended way afaik.
At the same time, Mac users will routinely bring up the Pro Display XDR and how they think it is the bare minimum and everything else is rubbish (*), with it coming in at a staggering ~200 PPD, 188 PPD, and ~150 PPD at 30°, 32°, and 40° hfov respectively. Whether the integer result at 32° is just the work of the winds, who knows. It is nonetheless a solid 3x the density that was touted so fine, you would "not be able to see the individual pixels". But if that was a lie back then...
The pixel density (PPI, PPD), viewing distance, and screen real estate discussion is not one with a satisfying end to it I'm afraid. Just a whole lot of numerology, some of which I sadly cannot help but contribute to myself.
(*) not a reliable narration of these sentiments necessarily