Line on Monitor when using Camera

[Danielzxzx]

I have always been wondering why when taking picture of my computer monitor on with my digital camera a line sometimes appear. When recording a video of my monitor on with my digital camera I can see a line scrolling down and then another line scrolling down after that one. I know this happens a lot of stuff but I don't understand why a line appears when looking at it through a digital camera. Without it I can't see any line. I always wondered what it really is so can anyone explain what that line is and why I can't see it without looking at it through my digial camera?

 

[pparks1]

This happens due to a refresh rate issue. Typically with a monitor, they refresh the screen at rates around 75 cycles per second. This is simply too fast for your eyes to see when you look at the monitor. However, with a lower frame rate on a video camera....it is out of phase with the refresh rate on the monitor and it will pick up the scan lines.

 

[Danielzxzx]

Ok, so that is what those lines were. Ok, thanks I always wanted to know what they were.