Shutter speed for green screen and 3 chip?

F

firehawk

Veteran
For years I've shot green screen at 1/60 but is a higher shutter recommended to reduce motion blur on moving body parts? (Have to watch out for light flicker if indoors of course)

And is it generally recommended to use a small 3 chip camera versus a single large sensor one? The large sensor can do much shallower DOF but the small one has 3 chips processing the colors.
In both cases, recording to 4:2:2 pro res.
 
My green screen experiences is mostly in sit-down/interview type work, but I have done some full body stuff, as well. But none of it was fast action. I have shot it with both 2/3" 3 CCD cams and single-chip s35. For 60 frame work, I shoot 1/60 and for 24 frame, I shoot 1/48. As far as depth of field, you want to stop down and have a pretty good DoF to allow for and make it easier to get a clean key. Everything else being equal, your lighting is gonna play a bigger role than 3 chip vs. single chip. If you're shooting in HD, most single chip cameras have at least an 8MP+(8.8MP) chip with the bayer pattern/filter laid out to give you full resolution in each primary color.
 
Keep in mind that when you're working with a shallow DOF for greenscreen, whatever you're going to make your background has to have the same DOF properties if you want to integrate it seamlessly, especially if you're achieving shallow DOF through a long lens.

Of course, if you're doing graphics or a weather map or somesuch behind, then it doesn't matter as much, but if you want it to look like a cohesive image . . .
 
Shutter speed alters the look of the motion. While it may be easier to use cheap quality keyers to key out your subject if there is no motion blur thats not how we see the world. You will end up with artificial looking material. Good keying software like Keylight in After Effects and the Delta keyer in Fusion should be able to handle motion blur with no problems as well as your screen is well lit.

Some people have used a higher shutter speed and then used software in post to attempt to add the motion blur back in but this just seems odd to me when it is so much easier to use a decent keying tool. Fusion is free so really there is no excuse anymore. Light the screen well and use a keying tool that can keep things like motion blur and glass/transparent fabric and you should be more than fine.

You shoot with the shutter speed that matches the rest of the production. If every other shot is 1/60th and your backgrounds are 1/60th then you will want the shutter to also be 1/60th. Don't let the crude keying tools dictate how you should shoot your material. Shoot it as it should be shot and use the tools that can deal with it properly.
 
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