02-01-2003 10:31									#1
	Some questions on refresh rates Help yourself to an AD-FREE life

I maintain my desktop @ 75Hz, and whenever i look at a 60Hz, my eyes start to hurt. is this psychological or is there a real reason for it?

what to laptops typically run at?

thanks

	02-01-2003 10:38									#2
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I know that changing from 70 to 80 or vice versa does the same for me. But since I cant notice the difference, I guess it's psychological.

When going down to 60 down, you can actually notice the screen "moving"(for lack of a better word).

	02-01-2003 10:40									#3
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quote: Originally posted by Eli I know that changing from 70 to 80 or vice versa does the same for me. But since I cant notice the difference, I guess it's psychological. When going down to 60 down, you can actually notice the screen "moving"(for lack of a better word).

yes, i see a "flickering" and then my eyes strain and i get headaches.

	02-01-2003 11:18									#4
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Normally, 60 Hz is sufficient to not get a headache. For comparison purposes, a movie runs at 48 frames per second (equivalent to 48 Hz), and a US TV at 60 Hz.

Some things to consider. Some lighting, especially in an office or school, has cycles as well. There could be unfortunate interactions between the two.

Also, some display technologies impact some people differently than others--such as some people seeing a "rainbow effect" on DLP projectors. Some technologies do not have real refresh rates--such as LCD screens.

Lastly, try changing the distrance between your eyes and display.

	02-01-2003 11:47									#5
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I would suppose distance is one major factor. That's why you have no problems watching TV at 60Hz but get headaches when using the same refresh rate on your computer display. I use 85 Hz myself.

	02-01-2003 12:03									#6
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Depends on the conditions, 60Hz can get you a headache.


Dan,

I thought the movies go at 25 fps?

	02-01-2003 12:22									#7
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I have to run my screen at 60Hz because of a cheapo graphics card that can't handle 1024x768@72Hz without distracting jitter, and pretty much the only way I can cope with it is making all backgrounds whose colour I can change completely black and using a very low brightness setting on my monitor. With more bright white on the screen I'd get eyestrain and a headache very quickly.

	02-01-2003 12:25									#8
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quote: Originally posted by Urban Ranger I thought the movies go at 25 fps?

IIRC, movies generally go at ~24 fps (something like 23.97 or something), with NTSC going at ~30 fps and PAL going ~25fps

I usually set my monitors at 75 or 80 hz.

	02-01-2003 13:35									#9
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Yeah, but isn't FPS a whole other thing than refresh rate? Play a game of Quake with 1024x768 pixels @ 80 Hz and you might get 75 FPS. Is that better than 800x600 @ 70 Hz and 100 FPS?

	02-01-2003 14:05									#10
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sometimes civ3 will crash my video drivers. I'm not sure what my refesh rate goes to. How do you check?

But when this does happen, any BB that has a white background looks real shitty. It looks like the white screen is pulsating. Very hard on my eyes. Reinstalling my video drivers does the trick.

edit: I checked my advanced video card settings. It shows my refresh rate at optimal. But I don't know what my actual refresh rate is at any one time. Any ideas?

	02-01-2003 14:15									#11
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Usually you can find it by pressing the configuration buttons on your monitor, so try fiddling a bit with those.

	02-01-2003 14:17									#12
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FH: 81.42 KHz
FV: 100.04 Hz

whatever that means

	02-01-2003 14:19									#13
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I always recommend 75 Hz as the minimum because then the chance of getting headache is smallest. However 85 Hz or more would be ideal, IMO. I'm using 100 Hz with both of my displays.

Diss,

your refresh rate is 100 Hz now.

	02-01-2003 14:29									#14
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yeah I figured it was the second one. I'm not sure what the first value is.

I admit I have never read the manual for my monitor . it's like reading instructions for a tv. You just plug it in and it works. Although maybe I should read my monitor instructions. I have things like moire, OSD position which I don't know the function of.

	02-01-2003 16:22									#15
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at lower refresh rates the screen will "tremble".

however, make absolutely sure that your monitor supports the refresh rate you have set for it.

otherwise it might break down.

	02-01-2003 16:38									#16
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Dissident: That's your monitors hsync, that is, how many times per second the electron beam that draws the picture on the monitor goes from one end of the monitor to the other horizontally.

	02-01-2003 18:47									#17
	Help yourself to an AD-FREE life

--"is this psychological or is there a real reason for it?"

A large number of people have that complaint, so there's probably a real reason for it It does vary by person and by conditions; flourescent lighting will make it worse. Personally, I never run below 75.

--"what to laptops typically run at?"

LCD monitors do not use a refresh rate per-se. Instead they have a delay time, the time it takes a pixel to light up or darken. However, this won't cause the same sort of problems the low refresh rate does, it'll just cause streaking in fast-moving graphics.

--"For comparison purposes, a movie runs at 48 frames per second"

48? I thought movies were 24.

--"Yeah, but isn't FPS a whole other thing than refresh rate?"

You're getting two different things mixed up. Refresh rate is how often the screen is redrawn. FPS as you are using it is how many full screens the video card can draw. FPS as it is being used above is basically equivalent to the refresh rate, namely how many times the image on the screen is redrawn.

Wraith
First snow, then silence
This thousand dollar screen
Dies so beautifully

	02-01-2003 22:38									#18
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"48? I thought movies were 24."

No. 24 unique pictures. But 48 actual frames on all modern projectors, including IMAX. The film contains two identical frames adjacent.

"I thought the movies go at 25 fps?"

OK, ignore the 24 v. 48 question for a moment. Even film shipped to PAL-land will contain 24 unique pictures. But the DVD pressing is adifferent matter. When a PAL DVD is pressed, it is first interleaved (making 48 fields), then pre-filtered so that you won't have wavy lines on interlaced TVs when displayed, then 2:2 pulldown is added which just repeats one frame/two fields per second to bringing it from 48 to 50 Hz.

For NTSC DVD, after interleaving and pre-filtering, when a DVD is played, the player adds 3:2 pulldown, meaning that one out of every five frames/two fields is just a repeat bringing it from 48 to 60 Hz.

Last edited by DanS on 02-01-2003 at 23:03

	02-01-2003 23:02									#19
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Most people somehow can see it. I, personally, can't tell the difference between 85 and 60 - I just don't see it.

	02-01-2003 23:13									#20
	Help yourself to an AD-FREE life

My laptop (LCD) runs at 60 Hz, though I don't seem to notice it as badly as 60 Hz on a monitor. I run my home monitor at 85 Hz, and when it occasionally drops down to 60 (Civ3 does this for a moment when it starts up, don't know why), it does hurt my eyes.

I think I heard a techincal explanation for why this is, but I don't remember all the details any more. Something to do with your brain beginning to perceive the individual images as opposed to "melding" them into one "continuous" image, or something like that...