Cinematography Mailing List - CML

Shooting CRT Computer Monitor (circa 1995 PC) at 23.98

I have a shoot with an actress typing on an old Windows PC at 23.98 with the Sony 900R. Hope to shoot some tests this week and am wondering if anyone out there has any suggestions for me to test that will minimize scan lines using the shutter on the camera and refresh rates on the PC?

The camera needs to move just to make things more complicated.

Russell Gienapp
DOP, Toronto

Keep the computer´s VGA refresh rate at 60Hz, also you may have to use the camera shutter at 120 Hz to totally eliminate the scan line that will remain slowly pacing on screen... Hope it helps


Emiliano López
DI Colorist - Post Prod. Managing & Consulting

Buenos Aires, Argentina

Isn't this a blatant advertising pitch? The question is how to shoot the screen with an actress and moving camera and his answer is "try not to see the screen very much"?

I'm sure the LitePad is a good product, but that isn't the point here. The question isn't how to light a person in front of a computer screen.

Roberto Schaefer, asc

There is a utility or Windows monitor tweak that lets you play with the refresh frequency of the CRT monitor -- CRTs will accept a wide range of signals -- and make it easy to shoot.

Also, I assume the camera you are using has clearscan or some similar ability to shoot CRTs and odd lighting.

Use non-flickery lighting (incandescent or carbon arcs, perhaps) and just tweak computer and or camera. This is simple stuff, there
should be lots of info re the Windows trick on the web, but with a modern HD camera you should be able to just tweak the camera's shutter speed and eliminate roll bars.

Putting an LCD in will scream "fake" to the audience, and who wants that?

Jeff "ever seen a Color Philco Predicta?" Kreines


I have an F900R and I have used Clearscan (just like any Sony video camera) at 23.98. In my case, I used it in control rooms where the computer screen refresh rates couldn't be modified, and were very unusual (36 Hz comes to mind...) So in and of itself this isn't a problem, even if you can't change the refresh rate of the CRT to a more 23.98-friendly frequency.

Where I have run into problems is on documentaries - often the very same places that have computer CRTs also have fluorescent practicals that I can't necessarily turn off/replace... So I get to choose what I want flickering, the monitor or the fluorescents. When you have more control over lighting, this isn't an issue.
George Hupka
Director/DP,Downstream Pictures
Listmum, Cinematography Mailing List
Saskatoon, Canada

Jeff Kreins wrote:

> Use non-flickery lighting (incandescent or carbon arcs, perhaps)

Carbon arcs? Those were used at the dawn of the computer age. I would say that something like flicker free (Square Wave) HMI's will be just fine. Also the high frequency of Kino ballasts is another discharge light that will not flicker with any reasonable shutter setting.

For the most part, a 60hz CRT refresh while shooting 23.98 has a lot less horizontal tearing than shooting at 60i. If you are on a dolly or panning you will still see a horizontal tear.

Carlos Acosta
DIT/Engineering/Custom Machine
Los Angeles

Carlos Acosta wrote:

>>Carbon arcs? Those were used at the dawn of the computer age.

It was a joke, Carlos. Roy Wagner will get it...

Jeff Kreines

Roberto Schaefer wrote:

>>The question is how to shoot the screen with an actress and >moving camera and his answer is >>"try not to see the screen very much"?

You are correct, Roberto. If the Director says "Now let's do a shot of the screen..." then that is what you are doing. The real answer is that any good 24 frame video guy can sync a 24 frame playback monitor to any HD camera quite nicely, and if you have 24 frame playback monitor, with or without sync, you can usually dial in a shutter angle that will mostly kill the sync bar anyway. I think it was 183 degree shutter the last time I tried it, but it depends on the particular hardware involved. The good news is that you can just try it on a test day and see what you get, because it is WYSIWYG.

David Stump ASC
DP/VFX Supervisor
LA, Calif.


Try to keep seeing the screen to a minimum. When not shooting the screen, turn it off, and adhere (tape or velco) a ROSCO 'Lite Pad' to the monitor. Click link below :

Photo metrics and sizes are on the web page. It is only about 1/4" thick. It's LED's that are 700 degrees Kelvin and very, very flat light.

Please contact, Tom Swartz at Rosco-Canada in Toronto (Markham)for availability.

Best regards,
Oliver Peale
Rosco US S.E. Rep

Quite right... I may be using some un-named flat led lighting source for certain shots ;-) But, my concern is being able to shoot the actress and the content of the screen at the same time (at 23.98) without the scan lines or asking post to track and comp something in later.

I just haven't shot a computer screen on HD 23.98 or films 24fps to date. Just NTSC SD that I tweaked the shutter speed to make it work. Or just used a LCD screen, which makes life much easier. I was even thinking about asking the art dept. to break open the crt monitor and mount a LCD inside as one solution.

Russell Gienapp
DOP Toronto, Canada

Copyright © CML. All rights reserved.