No eye fatigue on either one of them. That's what I'm saying to the OP. Nothing to do with the DPI in my post.
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Eye fatigue on my new ipp 10.5?
- Thread starter MarkB786
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No eye fatigue on either one of them. That's what I'm saying to the OP. Nothing to do with the DPI in my post.
Movies have 24 frames per second, but in movie theaters each frame is shown two to four times (depending on the projector hardware), making for 48/72/96 fps, to reduce flicker. You wouldn't want to watch actual 24 fps, it's jarring.
Liquid crystals, however, don't shut off between refreshs, hence they don't flicker. Flicker on LCD displays is either caused by PWM backlight modulation to control brightness, or by LC voltage inversion, which should be at least 60 Hz. I'd be surpised if either is the case on an iPad.
The variable refresh rate that Apple talks about is the rate of frames that are computed internally, before they are fed to the display. It shouldn't affect the quality of display in terms of flicker, but only in terms of choppiness/fluidity of movement.
Highly fluid movements can cause motion sickness when the perceived movement is in contradiction to the head movement as perceived by the cochlea.
Regarding the eye fatigue, I wonder if the resolution scaling (for apps that don't support the native reolution of the 10.5" iPad) might be a factor, as it slightly blurs the image.
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You have a source for that? I'd like to read more. I was under the impression that 24 fps was standard for movie theaters. I dont go to theaters often but is it common for digital projectors to do what you mention? Back in the day with film reels, each frame was displayed once as the projector rolled.
I believe it was 48 fps projected from pretty early on. Quote from Wikipedia:
From 1927 to 1930, as various studios updated equipment, the rate of 24 FPS became standard for 35 mm sound film. At 24 FPS the film travels through the projector at a rate of 456 millimetres (18.0 in) per second. This allowed for simple two-blade shutters to give a projected series of images at 48 per second, satisfying Edison's recommendation. Many modern 35 mm film projectors use three-blade shutters to give 72 images per second—each frame is flashed on screen three times.
(https://en.m.wikipedia.org/wiki/Frame_rate#Sound_films)
Yeah, that's what I thought I remembered from a review somewhere.
24 fps is the framerate, its still only showing 24 different frames per second. refresh rate in your above example would be 72 hz or 48 hz. Remember the older days with CRT monitors and some of the early FPS games, more often than not the framerate would be alot less than the 60 hz refresh rate of the monitor.
That's exactly what I said, reread my first post above. And as in your "older days" analogy, the variable refresh rate of the new iPads is not the display refresh rate, but the frame rate generated by the GPU/CPU.
"The stunning, redesigned Retina display in iPad Pro features ProMotion, a new technology that delivers refresh rates of up to 120Hz for fluid scrolling, greater responsiveness and smoother motion content."
Is Apple's wording off then? Should they have said up to 120 frames per second?
No, it isn't. 48 images per second isn't the same as 48 frames per second. Movie projectors are still only displaying 24 frames per second, although at a multiple resulting in 48, 72 or 96 images per second.
And the variable refresh rate of the new iPads is the display refresh rate. GPU/CPU update rates have been variable since the beginning, and are the result of the complexity of the rendered frame and the performance characteristics of the hardware.
The display needs to support 120 Hz refresh to support 120 fps imput. That's the "new technology", because on previous models the display only supports 60 Hz. As I wrote previously and you can read up on Wikipedia or elsewhere, liquid crystals don't require refresh, and hence there is no refresh rate on that level. Only the electronic curcuits that control the LCs need to support updates of the displayed image at whatever rate the graphics chip wants to output frames.
For that reason, what I'm saying is that when Apple talks about variable rates, then this doesn't mean that the screen itself has a refresh rate thatchanges on the level of the display hardware (i.e. in ways that could cause flicker and hence eye fatigue), but simply that the display is fed images at different rates.
I find it very interesting that I came across this thread. I have never experienced eye strain or anything unusual with my vision. After getting my iPad Pro 10.5 and using it pretty heavy for two days I noticed I was seeing double. In other words, when I would look at letters on the iPads screen I would see sort of two of each letter. It is hard to explain if you have never had it happen. It's like a font effect that has a shadow behind the letters.
I get this when I use the iPad for extended period of time, like over an hour or two at a time.
This never happened on any other Apple device. I'm hoping its temporary and is just my eyes adjusting to the new screen.
I also suppose it could be a coincidence that I developed it at the same time I received the new iPad Pro?
I get this when I use the iPad for extended period of time, like over an hour or two at a time.
This never happened on any other Apple device. I'm hoping its temporary and is just my eyes adjusting to the new screen.
I also suppose it could be a coincidence that I developed it at the same time I received the new iPad Pro?
My point was that in terms of flicker, the images you see flashing on a movie screen, i.e. separated by short moments of darkness, are 48 (or higher) per second. You are totally right that in terms of image content, it is only 24 fps, and I never meant to imply anything else.
As I wrote previously, liquid crystals don't have an inherent refresh (unlike CRT or plasma). It is only the interface between computer and display (think DVI, HDMI) that operates at a certain frequency for the purpose of synchronization. And GPU output is synchronized to that frequency, regardless of what rate images are generated internally within the GPU.
Maybe to put this another way: For a movie projector, it makes a big visual difference whether you project 24 frames at 48 images per second (with each frame doubled), or whether you project the same 24 frames at 24 images per second. The latter will flicker much more. However, that is not the case with the iPad screens, because unlike a movie projector or CRT or plasma screen, here is no light-dark cycle on LCDs. You do not see the refresh on LCDs unless the image content changes.
For that reason, I would rule out the variable rate mentioned by Apple as a possible culprit for the eye fatigue.
Imho, this thread is the biggest concern for the new iPad, and what's preventing me from taking the plunge for a 10.5.
This
http://gizmodo.com/5958439/incredibly-slow-refresh-rates-make-this-lcd-easy-on-the-eyes
That is also why epaper feels naturally.
I've noticed this too. I'm pretty sure it has to due with the new anti reflective coating that's used. I noticed the screen does not retain the colors properly unlike the 9.7-inch iPad Pro when viewing from an angle. I've tried 3 different ones and they're all the same and especially with the uneven yellow screen I will not be keeping the 10.5-inch.
May be this is cause by the backlit being too "directive" ?
Since the luminosity can change drastically with the angle from which you look at the screen, may be each eye see a too different image and it cause fatigue and pain ?
[doublepost=1497779882][/doublepost]
And it does come from the the glass or the coating :
Since the luminosity can change drastically with the angle from which you look at the screen, may be each eye see a too different image and it cause fatigue and pain ?
[doublepost=1497779882][/doublepost]
From what I have seen with my black 10.5", and black an white devices in store, this is specific to the black 10.5". Neither black 12.9" or white 10.5" show the green-yellow cast.
And it does come from the the glass or the coating :
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It all breaks down to some are more sensitive than others to the refresh rates. We are all not the same.
Agreed. I'm glad when a consensus is reached on what some may consider nit-picking wording of more technical matters. It's frustrating and wearying at times, but it helps to frame the discussion, to share the same perspective, to eliminate factors which prove unrelated and focus on remaining possible causes.
The display logic times output to the display panel at a rate that on other devices is fixed, usually at 60Hz, so the better written apps make use of APIs which help synchronize their renderings with the display refresh. This sometimes causes sync problems with content, such as movies or video which have mismatched cycles of 24 and 29.97(NTSC)/25(SECAM) FPS respectively. This is one of the reasons why the variable refresh rate of the new 10.5 iPP is so nice. It will allow the display to be refreshed at 48 or 96 Hz to sync perfectly with movies.
While LCD technology has no inherent need to refresh as CRTs did, most higher quality TVs do use a technique called backlight scanning to disable the backlight twice per refresh rate. This helps trick the brain into perceiving fast-moving objects as whole when going across the screen, instead of with a jerkiness. Many laptop and tablet displays may use PWM to implement this technique, but it doesn't appear Apple devices do.
I agree it's not likely that changing the refresh rate would itself cause eye fatigue. I would sooner expect a specific range of rates or pixel density to be factors.
I'd be curious which those are. The vast majority of the displays I've seen that use PWM are using it to control brightness, not to make motion clearer. It may do it as a side effect, but only at lower brightness (lower duty cycles), and it can have a tendency to introduce flicker. Asus a while back drove the PWM at 60Hz, which drove me nuts when the duty cycle dropped below 50%. Now that's eye strain, for me.
I'm thinking the issue is with the new anti reflective coating. My screen color is uniform but man does this screen mess with my eyes. I have tired it without ProMotion and true tone but that did not help. I don't no if I should just suck it up and keep it or go back to my air 2 and see how the next version of the 10.5 is next year.