Computer Screen 'lines'

[Weezle]

Something that's been bothering me:

I look at my computer screen and it looks clear and fine. However, last night i wanted to send someone a picture of what i had on my screen (no prizes for guessign what - and no, i couldn't email it!). However, when i look at my screen through my camera phone there are all these lines going across it. I've noticed this when you see computer screens on TV as well.

How come cameras pick up these 'lines' that are not visible to the human eye?

 

[REDLAND]

its to do with the frequency of the screen updates, but its too early to start explaining why

I'll have a coffee and get back to you

 

[Bigtomfu]

its to do with the frequency at which the screen refreshes- most computer screens refresh at around 60/70 Hz. this conflicts with the frequency of the filming device therefore you see the computer "refresh" over and over showing up the lines on the screen.

 

[Barnet Seagull]

Very good site for stuff like this...

http://electronics.howstuffworks.com/question336.htm