Going to something like a 49 or 55" television could work but you need to check the field of view at the distance they'll have it set up. Get a piece of cardboard at your largest anticipated screen dimensions, prop it up at their normal viewing distance, then put some high contrast marks on the edges & in the corners and see if they can make them out without too much head rotation. If they can't then cut the cardboard down to the next smaller TV size and try again.
Once you have bought the right sized TV, then adjust the resolution so they can make out screen elements (the window close button is a good one to test against). Then adjust the mouse size, browser zoom, etc.
>I was thinking of using an Ultra High Definition TV (49-inch with 3840 x 2160 pixels) but setting the resolution at 2560 x 1440. So it would be the same resolution but everything would be bigger.
I'd rather use OS level UI scaling you will have sharper and better picture
I tried various OS scaling methods. The problem with "magnify or zoom in on the whole screen" is that it's very cumbersome for an elderly person, easily getting lost on where you are on the screen. The problem with an OS configuration to make all text and icons bigger is that it doesn't do it for everything — many text labels, buttons, menus, etc., remain at a small font.
That's why I'm hoping a hardware-level solution (a much bigger display) is the answer.
Lens power is defined as the inverse of the focal length. Lets say you have glasses that, when combined with you eyes, create perfect focus at a range of 5m. If you look at something 10m away, you need to add (or subtract) the difference by modifying your built-in lense.
The lens stength adjustment for your eye needed for that, is
dP = 1/10m - 1/5m = -0.1m^-1. This is not much, and even old eyes can do this easily. Also, even if the eye is not able to do so, the image is going to be pretty sharp at 10m or any greater distance away, or even at distances of about 3-5m.
Now consider having your lenses adjusted to be perfect at 0.5m away. If you move the object you look at to 1m away, you get:
dP=1/1m - 1/0.5m = -1m^-1
This is still easy for a young person, but for someone older, this can be straining, or even impossible. Also, even slightly away from the perfect distance, perceived blurriness will be significant if not able to adjust.
Furthermore, to look at something much further away, eyes must be ajusted by dP=-2m^-1. This is doable for a young person, but an older will move around in the fog.
In other words, a screen that is 3m+ away from you requires a lot less lens compensation from the eye (and thus far less strain) than a screen 50cm away, even with perfect glasses, as long as you are not sitting perfectly still at that distance. Even variation in distance between the center of the screen and the edge of the screen may be enough to cause problems.
For the 4K screen, 1920x1080 is 1/2 4K so same point applies.
I think your idea would definitely help.
Sorry, I don't understand. The pixels would be bigger in the idea I'm proposing.
> A 27"+ monitor made ~10 years ago would be ideal.
That's exactly what they have now. I'm suggesting replacing it with a 49-inch monitor (a Ultra HD TV) set to the same resolution. The pixels would therefore be bigger.