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-   -   Shooting Computer Training Videos (http://www.dvinfo.net/forum/open-dv-discussion/4570-shooting-computer-training-videos.html)

katelins October 24th, 2002 08:15 PM

Shooting Computer Training Videos
 
Hello there. We have to shoot some computer training videos for our workplace soon, just wanted to know how we can best minimize the flicker you see from filming computer monitors. Any settings, lighting, or specific cameras (Panasonic AG-DVX100)?

Chris Hurd October 24th, 2002 08:33 PM

I can't recall immediately if the DVX100 has this feature, but the Canon XL1S and GL2 definitely do.

Jeff Donald October 24th, 2002 08:38 PM

What you're basically looking for is clear scan (sometimes referred to as variable scan). It is not available on all cameras. The frames per second (fps) is not a factor for computer monitors. The Canon XL1S has a clear scan range of 61.9Hz to 201.5Hz in 117 steps. This covers the range of computer monitors.

To the best of my knowledge the DVX100 does not have any version of clear scan for shooting computer monitors. The XL1 may very well be the lowest priced mini DV camera (only?) with that feature. Some of the larger (more expensive) Sony DVCam cameras and Panasonic DVCPro cameras have clear scan.

Jeff

Aaron Koolen October 24th, 2002 08:52 PM

You may be able to get away with things by changing the monitor refresh rate on all the monitors in your shot to say 60 and filming at shutterspeed of 60.


And, clearscan is good but it doesn't sit exactly on a fresh rate boundary. Well not for XM2 and my 85hz monitor. I think the camera goes to 84.8 so you still catch a bit of flicker..:(

Jeff Donald October 24th, 2002 09:06 PM

In most cases if you change your refresh rate (lower to 60Hz) your resolution will will change and all your screen graphics wil change accordingly. This is not an exact science. It requires some adjusting to get the right mix. In many cases each monitor will be custom adjusted because of differences among brands etc. In my opinion clear scan will give you much better results than a camera without. But Aaron points out the GL2 has clear scan and it is more affordable than the XL1S.

Jeff

Adrian Douglas October 24th, 2002 09:25 PM

Jeff,

sorry to disagree with you but changing the refresh rate of a computer monitor has absolutely no effect on the resolution. 800x600 at 60hz is still 800x600 even at 100hz. The higher refresh rate means the display will be clearer and sharper as it is drawn 100 times a second as opposed to 60 times per second.

Some people find that higher refresh rates can help if they spend long hours in front of the monitor.

Ted Jan October 24th, 2002 11:16 PM

if you have access to LCD monitors or a laptop screen, you then don't have to worry about flicker since LCD monitors/screens don't have that annoying flicker.

The Panasonic AG DVX100 has a feature called Sychro Scan which works on the flickering on a TV...haven't tested it out on a computer monitor, so I don't know if that feature will work for you.

Jeff Donald October 25th, 2002 05:29 AM

Adrian,

In the truest sense you are correct. But I don't know of any monitors that allow you to set the refresh rate independent of the resolution. When I go to change my refresh rate I am presented a menu of rates (60Hz to 124Hz) at various resolutions. My 21 inch monitor displays 1600 X 1200 at 75 Hz. If I decide the flicker is too objectionable with clear scan and I change my monitors refresh rate to 99 Hz my resolution changes to 1024 X 768.

Refresh rates are set by the manufactures of the monitors. Monitors come with a limited set. Video cards installed by the computer manufacture or end user can only display a limited set. The two sets of rates (video card, monitor) don't always coincide and the user has only a few rates that can be used.

daremo1971,

I downloaded the manual from the Panasonic site and it doesn't mention Synchro Scan, but it sounds like Panasonic's version of clear scan. Can you try it out? LCD displays are great for some work, but don't video well off axis. If you need to show people working at a monitor it is difficult to do with LCD displays.

Jeff

Jon Eriksson October 25th, 2002 06:40 AM

If you have access to AfterEffects or equivalent software, I would recommend you use that rather than filming the computer screen - you take any flicker away and the screenshots will be much easier to read as well.

Apart from that, there's not much to add to the posts above... ;)

Good luck with the shoot!


/Jon

David Mintzer October 25th, 2002 03:31 PM

Wow, you can do that with After Effects-- could you post the method because it beats me-----Adrian is correct, forget resetting your scan rate---I tried everything including some movie type capture programs but to no avail. I ended up shooting the site from my laptop screen and it works pretty good providing your set up is correct.

katelins October 26th, 2002 12:13 AM

Thanks for the help everyone. In summary I guess I'll have to try configuring refresh rates & resolution, filming an LCD monitor instead of a CRT one, or fake the computer environment with After Effects - perhaps as a special effect to make it look like we're looking at icons, or typing, etc?

daremo1971, I too am curious about the scan feature of the DVX100, do you think if you have some time over the weekend if you could film your computer monitor and tell us what the results are? Wonder why its not in the manual?

We may have to shoot this with the new Panasonic because my colleague is about to order it instead of the GL2. Maybe I could rent the GL2 myself for the computer screen shots...

Ted Jan October 26th, 2002 09:02 AM

Hey...just tried it out last night...

I had it set in 60i mode which is the F1 setting. Worked like a charm. Just need a little bit of tweaking on the camera and the flickering disappeared. You can go from 1/60.3 to 1/250. The Synchro Scan mode is in the manual at least its in my manual.

So the Synchro Scan mode works on regular tvs and computer monitors.

katelins October 26th, 2002 09:08 AM

Hey daremo1971, thanks so much! Its good to hear. Once again, I really appreciate you taking the time to check it out, mahalo.

Jon Eriksson October 29th, 2002 04:28 AM

<<<-- Originally posted by David Mintzer : Wow, you can do that with After Effects-- could you post the method because it beats me-->>>

Unless you need 'over the sholder' type shots (which you actually could use anyway - to cut between), there should be no problem in doing it in AFX. Just take a screendump of what page/es you want to film, take it in to AfterEffects. If you need a pointer to show where to click, just get one on a separate layer so you can move it around. Change to another screendump to show menus or other windows appearing.

The only thing to really worry about is to get a different screendump for everything that physically will change on screen.


It's not that difficult really - and you have the option of cutting out to an over the shoulder shot since it would all be in sequence...

Hope I've made some kinde of sense here... I do this at work all the time since screen shots are one of the more annoying things to try and sort out in editing...


Jon

David Mintzer October 29th, 2002 05:40 AM

JOn---thanks alot I will let you know how it goes!


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