shooting an LCD TV- 16mm

[Spencer Gilley]

hello

i will be soon be shooting a student film with couple scenes in which the main focus in the frame will be an LCD TV.

 

i am shooting 16mm on an ARRI SRII and was wondering if i will need to adjust the shutter angle to avoid having any sort of lines going across the TV screen.

i am in Canada, if that helps (so i believe i am at 60 hertz).

will some TV's react differently? i have read that i need a shutter angle of 140 degrees (with regards to shooting some computer monitors), but just wanted to make sure.

 

would doing tests with a Canon 7D, shooting at 24p, be a reliable way of seeing how it will look on film?

 

i greatly appreciate any help if you have had experience with a similar situation!

thanks!!!!

[Matt Read]

You shouldn't need to adjust the shutter angle at all. LCD screens show a continuous image without scanning each individual line like a CRT screen. Even if you play interlaced video, each series of fields will be shown instantaneously, rather than being scanned in, which is what results in the lines going across the screen.

 

Your biggest problem is going to be properly exposing the LCD screen so that it won't be completely blown out.

 

I have no idea how the 7D does its 24P video (whether it's a pulldown from some other framerate or some other process), but it should be a reasonable indicator of what you can expect to see on film. You can also use it to check your exposure of the LCD screen. It won't be 100%, but again, it should be a reasonable indicator of what you'll see on film.

[Mathew Rudenberg]

You shouldn't need to adjust the shutter angle at all. LCD screens show a continuous image without scanning each individual line like a CRT screen. Even if you play interlaced video, each series of fields will be shown instantaneously, rather than being scanned in, which is what results in the lines going across the screen.

 

Your biggest problem is going to be properly exposing the LCD screen so that it won't be completely blown out.

 

I have no idea how the 7D does its 24P video (whether it's a pulldown from some other framerate or some other process), but it should be a reasonable indicator of what you can expect to see on film. You can also use it to check your exposure of the LCD screen. It won't be 100%, but again, it should be a reasonable indicator of what you'll see on film.

 

I know it's old fashioned, but I would recommend using a spot meter to check the exposure of the screen, and make sure the brightest highlights don't go more than 3 stops over.

 

As Matt says, LCDs don't need any specific shutter angle, you should, however, be aware that most TV's are daylight balanced, and thus will turn out rather blue if you're shooting tungsten. Some TV's allow you to change the white balance, which you could use to adjust it closer to tungsten, you may want to leave a little blue in for realism, depending on your taste. This could be a good thing to check with your 7d.

[Saul Rodgar]

Some LCDs screens (particularly LCD projectors) do have a flickering in certain parts of the image, depending on their response time and how that interacts with the video signal it is getting from the source, both measured in Hertz. I mostly have seen it on projectors and screens taking VGA signal form a PC. Best thing to do is to run a test (video may work) at the same frame rate as your film camera.

Panning and dollying while filming off the LCD image can also present some problems. Test, test, test. That is the best advice.