Green Screen tips with EX1

Michael B. McGee

Michael B. McGee

Well-known member
i've read a lot of posts regarding green screen work with the EX1 and i'm a little overwhelmed with all the terminology. i'm new to the HD, DV world and would like some help with shooting green screen. basically, i'm looking for a "Green Screen for Dummies" book. any tips on lighting, camera settings:24p/30p, shutter; DoF; etc. i'm sure there's been previous discussions on this topic, i just haven't found the thread yet.

thanks to all who will reply. i appreciate your time.

-Mike:dankk2:
 
Lossy compression cameras are not so hot for greenscreen work, but this camera should do a decent job.

Lighting: The green screen should be about 1 stop over your key. Backlight helps separate fine details like hair.

Camera: Progressive is always good. The shutter speed should match your plate, but going too low might cause motion blur artifacting. The less DoF, the better. (To help blur and smooth out the greenscreen.) Just make sure you're doing everything you can to match your camera settings (and lens and distance from subject) to the plate you'll be replacing the greenscreen with.

Don't forget you can always look up terminology on wikipedia.
 
Conjecture and guessing can't beat real-world examples:

http://www.hawaiigoesfishing.com/videos/monterey_intro.mov

1080p30.
Green screen is at 50 IRE.
Keyed with Primatte and After Effects.

Note the stray hair in the composite.

If you do a Google search, there's a ton of info out there on how to properly shoot a green screen scene. And it's amazing how many DP's don't really understand how it works and get into trouble along the way.

Most important: that green screen is critical to success. Get a nice, even green screen at near-perfect exposure and white balance, and you'll get a great green screen with relative ease.

Mess up, and whoever is doing the composite will curse you.
 
the screen should NOT nececarily be 1 stop hotter than the key. It very much depends on your plate and the color of your screen.

As we are talking digital video, IRE40 is a good place to start for greenscreen exposure, but as I said it depends on what you are going to key over. Is it a dark background then it may be better to go a little darker and vice verca.

The most important thing is to get an EVENLY LIT rich/pure greenscreen. Get your lamps a good distance from you screen to avoid hotspots. Stop up and check with the zebra pattern that it covers the the whole wall and not just parts of it, then stop down to proper exposure.

Get your subject as far from the greenscreen as possible to avoid spill.

DO NOT shoot interlaced! This is not a good idea, especially not with cameras with low chroma sampling (like the ex1)

Everything that creates blur is going to make your keying harder, low shutterspeeds and low dof is very challenging to pull a good matte. Then again, if the plate calls for it you might have to do it, or somehow create the effect in post.
 
ok great. i'm unsure of IRE though. i've looked it up. still don't understand it and/or know how to monitor the levels. can IRE be view/monitored in camera or through a certain external monitor?

thanks.
 
You can read IRE directly through your camera using the Zebra setting.

Set your zebra to "50". When you start seeing lines in the green screen, you're there. And it'll immediately show what areas are lighter or darker than others.

I strongly recommend getting a green screen as evenly lighted as possible. Every five minutes you spend getting it right will save you an hour in post. Really. I just spent two days fixing someone's blue screen shots, less than 15 seconds in all. And the DP is very, very experienced.

The screen was dark. And some spots were folded slightly, making areas that were almost black.

The results were OK. But we spent a LOT of time making it look just OK. It would have been better spending all that time making it look just awesome.
 
And for the love of god, make sure you seperate subject from the screen at least 10 feet. I shot something last year and the location was way too small for the job. God only knows the nightmares they faced in editing.
 
Noel Evans said:
And for the love of god, make sure you seperate subject from the screen at least 10 feet. I shot something last year and the location was way too small for the job. God only knows the nightmares they faced in editing.
Click to expand...

Another suggestion: If the talent MUST stand on or work next to the green screen, don't let them wear white. White will easily pick up the green and guess what happens then! Better to have them wear something on the other end of the spectrum or something that won't be easily contaminated by all that green spill.

It's a subtle thing when you're shooting, but can be a big problem in post.
 
You must log in or register to reply here.
Back
Top