Apple Event Live Blog: iPhone SE, iPad Air, Mac Studio, and More

[ric22]

I'll calculate:
2' = 24", circle is 151"
217ppi is then 91px per 1°. (Which, btw, is not nearly enough for normally accepted visual acuity, which is on arc minute, meaning 2px per arc minute, meaning 120px per 1°.)

To get 91px/1° with 168ppi, you need the circle of 195", which leads to distance from center to the circle: 31".

Wow! 7 INCHES!

(That's less than my...)

Mark you position and keep your distance!

I don't know what you've been smoking today, but I want some of it.

 

[ric22]

"If you're sitting a couple feet from your monitor, 5120x2160 pixels stretched out over 34"+ is not "Retina"."

I lost track of who said this, but I think they're wrong. At 5120x2160 on a 34" display, you'd no longer be able to discern any increase in pixel density at a distance of 21" or greater. At 2 foot away, it would appear as crystal clear as it possibly could- aka a 'Retina' display.

Here's a handy calculator: https://www.designcompaniesranked.com/resources/is-this-retina/

 

[Mainyehc]

Seems to be about £500 here in the UK so you could get three for the price of Apple's offering.
Two might be interesting...

I mean, that second LG I'm eyeing is only €400… I could buy four for the price of Apple's gizmo.

And, seeing how I've already got one and the Studio supports up to four Pro XDR Displays and a 4K HDTV, I could have an array of 5 4K LGs connected at the same time. Not that I need them, but I could. ?

 

[theluggage]

To get 91px/1° with 168ppi, you need the circle of 195", which leads to distance from center to the circle: 31".

Let's try that again:

The definition of retina - an Apple term - is the angle made by a 1/300" pixel at 12" (see: https://www.designcompaniesranked.com/resources/is-this-retina/)

The angle in radians is the circumference of the arc divided by the radius of the arc. Where the arc is much shorter than the radius (1/300" vs. 12") that's effectively the same as the width of the pixel over the distance.

So the retina angle a = 1/(300 x 12) = 1/3600 radians. That's your magic retina constant*.

The magic test then is (pixel size/distance) <= 1/3600.
Or, furtle that a bit and distance > 2400 / ppi

So for 168 ppi, the retina distance is 3600/168 = 21"

...which is what the online calculator above will tell you if you put in 5120 by 2160 @ 34" (actually 163ppi not 168 but that's insignificant).

* 1/3600 radians * 180/pi = 0.0159 degrees = 57.3 arc seconds ~= 1 arc minute. There you go.

 

[jquest68]

The event was so boring. They should have called it the "M1 Event" because all they did is upgrade the speed on old products. Oh yeah, and announced a very expensive desktop computer. A 27' screen? why not bigger if it's only a display? The Studio Mac? it's a beefed-up mac mini with a faster chip.

 

[toke lahti]

Let's try that again:

The definition of retina - an Apple term - is the angle made by a 1/300" pixel at 12" (see: https://www.designcompaniesranked.com/resources/is-this-retina/)

"around to 10 to 12 inches away from your eyes" was just a simplification from Steve Jobs.
After all the idea of retina screen is that you can't sepatare pixels, isn't it?

You need TWO pixels per acr minute don't you?
"Line pair" was the old analog way to say this, wasn't it?
Or are we thinking about Kell factor here?

Changing from degrees to rads does not change anything.
You (EDIT: @killmoms) said 27"5k is retina from 2'=24" is enough.

I just calculated the same POV resolution for 34"/5k.

Was there a mistake in my calculations?
You know, I'm used to SI units, like the rest of the world.

 

[toke lahti]

So for 168 ppi, the retina distance is 3600/168 = 21"

...which is what the online calculator above will tell you if you put in 5120 by 2160 @ 34" (actually 163ppi not 168 but that's insignificant).

So the 34"/5k IS "retina" at 2'=24"?

 

[theluggage]

You need TWO pixels per acr minute don't you?

I just checked - from Wikipedia (Wikipedia is the best I can do for the moment, sorry):

6/6 vision (nb: 6/6 is metric for 20/20) is defined as the ability to resolve two points of light separated by a visual angle of one minute of arc, corresponding to 60 PPD, or about 290–350 pixels per inch for a display on a device held 250 to 300 mm from the eye.

So the model here is treating pixels as separate points of light - of course, real life pixels are made out of RGB sub-pixels anyway, and is this about being able to visually separate individual pixels or to notice that the edge of a shape has pixel-sized steps? This is all rule-of-thumb stuff - but 300 ppi @ 12" is Apple's definition of "retina" and also corresponds to the "standard" for printer resolution since the 1980s.

Changing from degrees to rads does not change anything.

It makes it much easier to convert from pixel size and distance to an angle, without having pi floating around....

Was there a mistake in my calculations?

I thought you got "retina at 7 inches" (instead of 21) - maybe I misread?

So the 34"/5k IS "retina" at 2'=24"?

Yes.
Or to keep it much simpler, double the distance, halve the PPI needed for retina, so 300 ppi at 12" goes to 150 ppi at 24".

 

[toke lahti]

@theluggage ,
I wrote it badly, I meant 7" difference.
And I mainly wrote it to show that the difference is quite small and there not so much point to draw sharp line somewhere, when "there's enough resolution".
It is just about individual behavior how far you keep your eyes from the monitor.
Which usually does differ comparing if you use only one monitor or several of them.

I had much bettervision than 20/20 when I was young, especially the left eye.
Now that I'm over 50, my vision has degraded to mortal levels. So I don't need or want supersharp anything anymore.

First step to "enough resolution" is not to be able separate rgb-subpixels. Some of us remember the time, when that defined the viewing distance of crt-tv.

How much data is resolved can be measured by MTF curve.

Optical resolution - Wikipedia

en.wikipedia.org

says that: "The best visual acuity of the human eye at its optical centre (the fovea) is less than 1 arc minute per line pair, reducing rapidly away from the fovea."

So that the two pixels, other being black and other white, for not being perceived as one gray dot, I'd say 2px / arc minute is good "rough point".

And the print industry didn't stop to 300dpi because it was perfect, it stopped there, because it was practical. Pretty much same thing than with cd audio etc.
Somehow it is usually forgotten that SJ said "from 10" to 12"" and just one number is picked from there...
Retina display was a practical decision, not some scientific theoretical limit.

 

[toke lahti]

I agree, that 300ppi @ 10" to 12" is good enough definition to "Retina display".If we take that 10", then 163ppi is good for 18".
And 300ppi@12" is as good as 163ppi@22".

Why people are saying that you need 217ppi?

 

[jdb8167]

And what is the official definition of "Retina"?

Deleted. There is already a better Retina calculator posted here.

Edit: Using the calculator posted, Apple's definition for a Retina computer display is a typical viewing distance of 20 inches and something better than 57 pixel per degree (PPD) though for computer displays the minimum on an Apple display is 76 PPD.