Help - shooting computer screen w/o scan line

JackW wrote on 8/22/2005, 4:04 PM

I have a four hour shoot coming up in the next couple of days, much of which will include text and graphics on a CRT video monitor. I'll be shooting with a PD-150 in a room in which I can control overhead lighting, so reflections and glare shouldn't be a problem.

However, I've tried numerous shutter speed settings, thinking that might make a difference, but I still see a rather slowly moving scan line coming down at regular intervals from the top of the monitor.

Is there any practicle way to avoid having the scan lines on the CRT screen show? I've suggested a video projector to the client but so far without any success.

Jack

Comments

rs170a wrote on 8/22/2005, 4:23 PM

If at all possible, replace the CRT with an LCD (orr use a laptop) and your problem will be solved.

Mike

B.Verlik wrote on 8/22/2005, 4:37 PM

If you can set the refresh rate to 60Hz, you should be able to shoot it. I shoot my LCD display at 75Hz and it looks pretty good. Also, some cameras, you have to turn off the Motion Correction to shoot the screen.

Liam_Vegas wrote on 8/22/2005, 4:55 PM

Exactly as Mike said.... I did this a while ago at a shoot. I used a VGA signal splitter to allow me to attach my own LCD monitor without impacting the presenters. I then positioned my LCD monitor out of the way and captured the screen without bothering anyone.

Worked great.

JackW wrote on 8/22/2005, 5:04 PM

Thanks all. Good advice. I'll try the splitter and separate monitor route, which has the added advantage of getting me out of the presenter's way.

Jack

Jeff Waters wrote on 8/23/2005, 4:43 AM

Not sure if you intend to have the text and graphics in the background of a framed shot or if you intend for them to fill the screen???

If the latter, Camtasia from Techsmith is the best computer based screen recorder I've used. ( www.techsmith.com)

Jeff

Galeng wrote on 8/23/2005, 1:08 PM

I am not sure if the PD-150 has this same feature, but with my GL2 there is a feature called Clear Scan. With it I can adjust the camera to the same horizontal refresh rate as the monitor. It's really neat as I can see all the scan lines when I first look at the monitor, then go to Clear Scan and start adjusting the refresh rate settings. The scan lines begin to disappear and when I hit the right refresh rate they are totally gone!

johnmeyer wrote on 8/23/2005, 1:21 PM

I just did a quick search of the Internet. Most advice is to change the refresh rate of the monitor or the shutter speed of the camera. If your camera has variable sync rate (most consumer cameras do not), use that. You can read more about this by using this Google search:

Google results for flicker reduction

or use these Teoma results:

Teoma results for flicker reduction

birdcat wrote on 8/24/2005, 4:49 AM

Silly question - Do you need to shoot the screen? Can you get a copy of the presentations and capture them directly, then edit them into your final? That way you just focus on the presenter(s) and cut directly to their presentations when needed (even use PIP if you want)

JackW wrote on 8/24/2005, 9:16 AM

Hi Birdcat: good idea. This is what we normally do when the speaker has a PP presentation.

However, for this particular shoot a trainer is teaching a "student" how to use a complex electrical generating control system. The client wants to see how the student works at the various screens that pop up on the computer monitor. It's the interactivity that they want to document.

If it arrives in time we're going to use the signal splitter referenced above, which we ordered direct from the manufacturer (no one seems to have it in stock). If not, I'm taking along a flat panel monitor that I hope to be able to substitute for their very old CRT monitor. By setting shutter speed to 1/30 of a second I can minimize the scan bar and if all else fails we'll have to go with that.

JackW wrote on 8/24/2005, 9:18 AM

Hi Birdcat: good idea. This is what we normally do when the speaker has a PP presentation.

However, for this particular shoot a trainer is teaching a "student" how to use a complex electrical generating control system. The client wants to see how the student works at the various screens that pop up on the computer monitor. It's the interactivity that they want to document.

If it arrives in time we're going to use the signal splitter that Liam suggested, which we ordered yesterday direct from the manufacturer (no one seems to have it in stock). If not, I'm taking along a flat panel monitor that I hope to be able to substitute for their very old CRT monitor. By setting shutter speed to 1/30 of a second I can minimize the scan bar and if all else fails we'll have to go with that.

Jack

Liam_Vegas wrote on 8/24/2005, 10:02 AM

If not, I'm taking along a flat panel monitor that I hope to be able to substitute for their very old CRT monitor. By setting shutter speed to 1/30 of a second I can minimize the scan bar and if all else fails we'll have to go with that.

You do not get that scan/line flicker when you capture direct off an LCD monitor. So you should not need to set the shutter speed to 1/30 sec. Leaving it at 1/60th should be fine.