Quote: "My LCD monitor goes up to 75Hz, which is what its set too - anything lower and I can see the raster beams...
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ROFL, thats because you are insane and deluded
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CRT monitors work differently to TFT, in a crt monitor a scan beam zips down the screen a line at a time and draws the picture you see, by the time it reaches the bottom the phosphors at the top of the screen have started to fade, by the time the scan beam has been pulled back to the top they have faded and that section of the screen is as black as it is when you have it turned off, then the beam redraws the image on the freshly blank screen, it does this 50 times a second for tv, 60 to 120 times a second for a monitor.
monitors have a higher refresh rate (the phosphors are cheaper and don`t hold an image for as long as your TV phosphors can), so you need to refresh the screen more often, otherwise you notice the fade to black of the longest drawn section of the screen (flicker).
turning the scan speed up makes the pc redraw the fadeing section of the screen sooner, the limit is set by the makers, you can`t refresh faster than the old image fades, otherwise you would end up with a screen that has the previous frame drawn under the new one, and it would get very bright as the phosphors got more and more charge built up.
some examples of a phosphor that persists for a long time are the old style revolving radar display, those blips that showed a target did not persist because of fancy electronics drawing a slowy fading blip, but because they chose the phosphor to glow for long enough that the dish could revolve around once before they had totaly faded, another is the old green screen monitors from my early PC days, much sought after since they didn`t give eyestrain due to the green phosphor persisting so well (although they later found it gave your vision a red bias after looking at one all day)
TFT monitors on the other hand don`t fade, the dot is held at the specified colour and doesn`t alter until it is told too, then it will switch to the new colour, so you don`t get any flicker apart from the phosphorescent backlight that lights the screen which operates on the same basic principle as a lighting tube or low energy bulb, but it`s flicker is outside your control (set at about 100hz).
thats why when you photograph a monitor with a digital camera a CRT has a blank band thats unreadable (unless the refresh rate is faster than the cameras CCD), while on a TFT you just notice a shadow where the monitors backlight and the scan of the CCD went into and out of sync.
if you take a screenshot of a monitor with a broadcast(TV company) camera or a ordinary film camera you can tell which monitor is which, a TFT shows up clearly in the photo, a CRT has one or more bands in the image, think back to a news broadcast where people in the background are using CRT, you can see the screen flicker from strobe effect, if they have a tft screen then you just see a faint shimmer from the backlight.
the difference for TFT is in the speed it can alter the image, TFT has several million little LCD windows placed in front of colour filters, these windows can be on, off or at any in-between value, the speed that a pixel can change colour depends on how fast the LCD can change, if you have noticed when working fast on a LCD calculator, there is a percecptable lag.
TFT screens have lcd components chosen for speed, but they are not as fast as a fast CRT monitor, so if you have a very fast movement on a good CRT it looks "clean", no smearing, the same fast movement on a TFT will (depending on the quality) leave a "smear" or "rip" where the lcd "windows" are changeing back to their background colour not quite fast enough, heres a bit of a snippet that shows this, alter the speed with the up/down cursor keys.
make object sphere 1,1
autocam off
position camera 0,0,-5
point camera 0,0,0
color object 1,rgb(0,0,0)
color backdrop rgb(255,255,255)
speed#=0.01
xlocation#=0
do
if upkey()
speed#=speed#+0.00001
endif
if downkey() and speed#>0.0
speed#=speed#-0.00001
endif
xlocation#=xlocation#+speed#
if xlocation#>5.0 then xlocation#=-5.0
position object 1,xlocation#,0,0
loop
note that on a tft display the effect will not be at all what you are expecting, but thats because in a detailed scene the brain is too busy processing movemment to notice minor detail, movies on TFT etc all look like this when in motion, but you don`t notice it, it only becomes noticeable in controled specific examples like this.
the upshot of all this rambling is to say that a TFT can have a far slower refresh rate than a CRT and still look flicker free, there are a lot of stupid claims about refresh rate going about, basicaly you don`t notice refresh above 20fps when looking head on, but peripheral vison will show a noticble flicker (look out the corner of your eye at the the screen) since the peripheral vision receptors are mosly black and white and respond faster to light change.
the TV standard 50 fps was chosen after much research as the best refresh rate to view without tireing the eyes or causeing headaches, computer monitors have higher refresh requirements for reasons of cost and because the PC can supply faster refresh rates, it`s not so that you can play games better, most manufacturers make their money selling monitors to corperations and governments, you may have one or two monitors at home (replaced rarely) the local council offices use thousands and replace em every two years or so.
controled tests show that people claiming to see anything different above 40 fps are in error or just seeing what they expect to see, framerate flicker is detected by the periphery of your vision where the black and white receptors are (they evolved to allow you to detect movement like approaching predators quickly in low light) as long as you are looking directly at the screen you won`t notice any flicker since the colour rods and cones have a slower fire rate and cannot detect change so fast, hence the term Persistance of vision, thats what make you see sparklers (fireworks) as bright trails of light in the dark, the high level of light triggers the slower colour receptors.
Mentor.
ps: before anybody starts there
are some generalisations and simplifications made in this post, someones bound to have a go at it since the facts are not in line with what is "known" by "common knowledge".
PC1: P4 3ghz, 1gig mem, 3x160gig hd`s, Radeon 9800pro w cooler (3rd gfx card), 6 way speakers.
PC2: AMD 2ghz, 512mb ram, FX5200 ultra, 16 bit SB.
Mini ATX cases suck.
