DVL-Digest 872 - Postings: Index computer monitor flicker Virus warning! macs computer monitor flicker - "Perry" Masi: I guess we haven't discussed this for a couple of weeks! >I am trying to take a shot with a computer monitor in it that is on. Unfortunately, the camera is reading the display on the computer monitor with a flicker of sorts. Actually it's alternating bands of light and dark (not black) passing through the computer monitor from top to bottom.< What actually happens is that part of the computer display is exposed with say 3 frames, and part with only two frames. So you can either see the 2 frames as a dark band or the 3 frames as a light band depending how you look at it. The bands move because the computer and camera are running at different speeds. >Is there a trick to changing the settings on the computer monitor or the camera to get the monitor to look like it does in real life? I notice this only happens on my desktop but not on my laptop.< On consumer cameras you need to change the computer setting to match one of the available shutter speeds. The obvious one in NTSC land is 60Hz, which is the original VGA speed and usually an option. Unfortunately you are probably using PAL which needs a multiple of 50Hz. If you are lucky a recent computer display will go to 100Hz. A slightly messy workaround if you have a camera like VX1000 with slow shutter speeds is to use 25Hz and switch the computer to 75Hz, but this will give you some motion blur. Some PAL cameras have a 60 Hz shutter which means you can use the NTSC trick. As you have found, LCD displays work differently and don't give a problem because they have a constant display that doesn't flicker. Pro cameras usually have a continuously variable shutter which enables you to dial the exact speed needed to remove the bars, although there are still some artifacts when the camera pans. If all else fails, just turn the computer display contrast down (so that it is not so intrusive) and put up with the effect. We see it every day on broadcast pictures so it is no longer a big no-no! Perry Mitchell Video Consultant http://www.perrybits.co.uk Virus warning! macs - "Perry" >All you guys with windows machines - keep off the Mac platform! Our small market share is the only thing that saves us from this nonsense.< I have 5 working Macs in the house and have been using Macs for 15 years. I have the one solitary PC I use for the Internet. By an amazing coincidence I picked up my first and second virus infections (ever) on this last same weekend, one on either platform! The Mac one was particularly nasty (to me) and corrupted the system files. I suppose in general viruses prefer to keep the machine alive and concentrate on reproduction. Actually in retrospect I've had a few strange crashes that needed system re-installs, so maybe I ought to say they were my first confirmed viruses! Perry Mitchell Video Consultant http://www.perrybits.co.uk (diese posts stammen von der DV-L Mailingliste - THX to Adam Wilt and Perry Mitchell :-) [up] |
 slashCAM  News HD Camcorder database One-on-One Cam comparison About our tests About us |
|
|
