View Full Version : Weird Real-Life Motion Blur

04-06-2003, 05:51 AM
take a pencil or pen and waggle it in front of you, between yourself and the monitor. you will see that there is a 'strobing' effect. and there is hardly any blur. do the same but facing a flourescent light or anywhere else except the monitor and you will have a blur.

can anyone explain why this is so? (the intensity of the monitor, maybe?)

Elmar Moelzer
04-06-2003, 07:12 AM
Hello Faulknermano
This si easiyl explained.
The brighter something is the stronger its effect on on your retina.
Look at a bright light for a time then close your eyes and you will still see it (well some sort of an effect like that), you certianly noticed that before. It is that the bright light kinda burns itself into the retina.
This is why bright things leave traces in your retina as they move and they need some time to disappear. This makes for a stronger motionblur on them.
I dont know any 3d- software that does really simulate this. The only thing I have see that comes close to simulatng this is the X- Dof- plugin (some samples on their page show it well).

04-06-2003, 08:44 AM
hi elmar.. well i'm not sure i get it.. i mean i get what you're saying but i dont get how it relates to the motion blur. it seems that the pen i'm holding, when i'm shaking it, doesnt not have any motion blur when i'm holding it up the monitor. i have a very dark desktop and it still exhibits no mot blur. but even if i hold it up in broad daylight it does. i'm not talking about how light, per se and how that is mot blurred. it's like the the FPS of my eyes goes up when i'm looking straight into the monitor. :D

04-06-2003, 08:52 AM
It has to do with your monitor's refresh rate. Try turning your monitor down to 60Hz and shake the pen again, the effect should be even more pronounced.

I have an LCD monitor, LCD's don't constantly refresh like CRT's so when I shake a pen in front of it, I don't get a strobing effect at all.

Elmar Moelzer
04-06-2003, 09:57 AM
Aha, hehe sorry, I have soemhow overread the monitor part.
Well, I think it is related to the refreshrate of the tube. You certainly know the flickering (or moving lines) effect one gets from filming a monitor- screen with a videocamera...
I think it is somehow related to that.

04-06-2003, 10:58 AM
coool. looks pretty weird heh? :)

jin choung
04-07-2003, 01:53 AM
it's the reason why blur is reduced in a photograph when you use a FLASH on your camera.

the flash 'imprints' a strong image onto your retina for the duration of the flash (VERY VERY BRIEF).... because the duration of the flash is so brief, it is equivalent to taking a picture with a very short exposure time.

the inverse is taking a picture with a very long exposure time - which can result in traffic leaving light trails, allows you to draw your name in frame with a pen light, etc.

so with light sources that PULSE - like flourescents or your monitor, it's like have 60 extremely brief flashes a second imprinting distinct images instead of a blur.

notice that if you do this with non strobing lights like incandescents or the sun, you don't get this effect.


p.s. you should also try holding a long pencil loosely between two fingers near the middle and with a light touch jiggling up and down. it looks like the pencil is melting or flopping like rubber.... neat effect.

04-07-2003, 02:20 AM
Set your refresh rate higher guys or you`ll get eye strain!

Nothing to do with monitors, but...can you do the floating sausage trick? Point your two index fingers at each other, close infront of your eyes and focus through them into the distance. :D

Something to do while waiting for that render!


04-07-2003, 05:44 AM
Key word is "strobing". Strobe lights blink rapidly, so does your monitor. Very rapidly.