Why do we other see a computer blind on t.v. rolling resembling the vertical hold is messed up?

Answer:

The computer peak or any CRT screen for that business does not render the whole blind at all times. It is only making line by strip, be it interlaced or progressive. These fields are honourable at confusing our eyes to think that the in one piece screen symbol (frame) is always available to us. Our eyes cannot see the difference. With the video demo equipment, since the shutter speed is fast it catch the frame lines and you actually see the field.
It probably has something to do beside how a monitor refreshes and how in that are 29 or more frames per second in picture. Film is slower than our eyes, so it picks up things that our eyes miss.
You see that because the frame rate of the monitor and the frame rate of the camera filming aren't surrounded by sync.
The effect is that of a stroboscope. If the computer screen and the TV camera enjoy different refresh rates, after the picture will appear to roll at the difference. E.G. my CRT monitor has a 75 Hz rate, and current US TV uses NTSC standards, almost 60 Hz, so recording the computer would flicker at ~15 Hz. A similar effect occur when filming HGV wheels: at some speeds, the wheel even seem to rotate to the rear!

To prevent flicker:

1. Use an LCD display; they have a highly developed latency than CRT.

2. Synchronize the monitor with the recorder. Unless done exactly, in that will still be a slow roll.



You could use a CRT display as a stroboscope: write a simple program to alternate black and white screens at a settable rate.



You can also use the CRT (or TV) to weigh the speed of a camera shutter: looking through the back of the camera, the TV picture would look merely half-drawn at a shutter speed of 1/120 second.

hip hop abs program