Shooting TV Screens

[Marshall Rose]

Anyone have any tips for shooting a TV screen (yes, with red) to avoid getting those wavy lines? I forget the term for those "wavy lines" (degauss maybe?), but just to clarify, I'm talking about the vertical lines that are sort of bent, NOT the big horizontal lines that shift up and down - i can avoid those. I'm shooting at 29.9 on my camera and the HD LCD screen is set to display at 60hz.

thanks

 

[Justin K Phillips]

Have you tried throwing the screen slightly out of focus?

 

[ericyoung]

The term is moiré. Justin's suggestion is one way of reducing it. Another would be to adjust your lens zoom/focal length and/or move closer further away to reframe - this will change the moiré and you may find a combination that minimises it. You could also try a lens filter that slightly softens the picture.

 

[Marshall Rose]

yes, and that does work - but i ideally i'd like to have it tac sharp. I know i could key in the image to the television sometimes, but i won't always be able to do that.

 

[Marshall Rose]

thanks eric! so basically the moiré is a fact of life and i just have to do things to minimize it through framing, focal length, focus, etc?

 

[Matthew Bennett]

TV Moire is cool, embrace it.

 

[Neil Larson]

Green screen?

 

[ericyoung]

thanks eric! so basically the moiré is a fact of life and i just have to do things to minimize it through framing, focal length, focus, etc?

Yes, it's a fact of life. Moire is an aliasing phenomenon, and will be significant anywhere discrete sampling of patterns occurs, where the sampling frequency is comparable to the pattern's optical frequency. eg, the discrete pixels of the RED CMOS sensor sampling a high frequency grid of LCD pixels from a distance.

http://en.wikipedia.org/wiki/Moiré_pattern

There are Photoshop plugins for reducing captured moire patterns, but they would probably not work well for moving images. It's much better to reduce them in the camera before recording!

 

[Kim Frank]

If I remember right I did read that you can get rid of it by changing the shutter angle by a few degrees. I'm sure someone over here will elaborate that technic.