Originally Posted by claw
What size screen at 13ft? Do you have a calculator for that determination?
Yes there are some online calculators. As morphinapg says it is to do with the visual acuity of the human eye. With 20-20 vision there is a maximum amount of detail you can resolve at a given distance. If you were an eagle, this would be more detail at the same distance.
Notes cribbed over the years:
I believe that for 20:20 vision the limit of visual acuity is one arc minute, which is equivalent to a pixel-width of 1.16 mm or 0.046 inch at a viewing distance of 4 metres. It is not uncommon for people, especially young people, to have much better resolution than that. The maximum human visual acuity is said to be around 30 seconds of arc or twice the 20/20 resolution.
has some figures but it's often more useful to see the ranges graphed out like below. The ranges are the "top" and "bottom" of each "fan line". At the top of each zone, you can only just detect any difference. At the bottom, you can fully see every pixel.
In fact even the industry bodies involved can't agree on a single solution, so ultimately it should come down to personal preference.
this is my personal annotated version of their graph:
As you can see, at the distance I sit I "should" have bought a 65", but actually all I could afford/justify at the time (and I take the view that the tech is changing too quickly to make a big long-term investment) was the 55". However, I can definitely see a clear improvement with 4K over 1080p, so I'm very happy.
(This also shows why, IMHO, 8k in the home will be a waste of time. The size of screen I'd need is already completely off the scale, and would be double the size of my wall.)