60I or 30P for Green Screen?

[Kevin Lewis]

I typically shoot greenscreen for the web. When I do, its 30p. My next greenscreen shoot will be going to both tv and the web. In this case, would It be best to shoot 60I? Any concerns with shooting 60I for greenscreen?

[Robert Turchick]

I only shoot progressive these days. Occasionally I will get greenscreen footage that's 60i. I deinterlace and convert to 30p. I've only done a handful of broadcast stuff on my greenscreen and it looked great on TV. Web stuff is my primary market and 30p is perfect.

One trick for shooting 30p on the greenscreen is use at least a 180deg shutter. This will reduce motion blur which makes keying easier. My studio has a permanently lit, painted cyc wall and floor. I do an average of 2-3 shoots a week. Keying is handled by Primatte Pro in AE CS6.

[Eric Olson]

Originally Posted by Kevin Lewis

I typically shoot greenscreen for the web. When I do, its 30p. My next greenscreen shoot will be going to both tv and the web. In this case, would It be best to shoot 60I? Any concerns with shooting 60I for greenscreen?

If you are recording 4:2:2 or 4:4:4 color then either interlaced or progressive should key fine. However, when shooting using a 4:2:0 colorspace codec such as HDV or AVCHD then you need to be very careful with 60i material. A surprising number of workflows don't handle the interlaced 4:2:0 color planes correctly and result in choma upsampling errors that are often reffered to as the chroma bug.

4:2:0 chroma bug - Google Search

Even with an optimal workflow, 60i HDV and AVCHD footage can be difficult to key. In this case, it is easier to start with progressive 60p, 30p or 24p source.

[Kevin Lewis]

Robert, I typcically shoot greenscreen at 30p with the shutter set to 60. I am in a controlled lighting situation using halogen lights. Under these circumstances do you still suggest setting the shutter to 180?

[Eric Olson]

Originally Posted by Kevin Lewis

Robert, I typcically shoot greenscreen at 30p with the shutter set to 60. I am in a controlled lighting situation using halogen lights. Under these circumstances do you still suggest setting the shutter to 180?

When shooting 30p a shutter speed of 60 is the same thing as 180 degrees.

Rotary disc shutter - Wikipedia, the free encyclopedia

[Robert Turchick]

Ya beat me to it Eric! Yup.. At 30p 1/60 shutter is 180deg.

And 4:2:2 makes a HUGE difference from 4:2:0. Ive only keyed 4:4:4 footage once. By far the best solution but the camera system (sony hdc-1500 and its separate recorder)costs almost what my house is worth so I'll be sticking to 4:2:2 for a while. Very interested in the Blackmagic camera's raw option but would go broke trying to store all that footage!

[Kevin Lewis]

Thanks for the input guys. I'm going to stick with 30p.

[Dean Sensui]

What you do not want to do is shoot interlaced for any kind of compositing.

It adds an extra step in the process, and has potential to degrade the results.