Green Screen Advice

[George Kroonder]

Originally Posted by David Scattergood

The initial phase is for me to show some test green screen footage hence the living room.

You can actually key on just about any color, not just green or blue. As long as you have enough contrast between the subject and an even color, todays keyers will do a good job. Certainly enough for a test.

Is spill really that obvious when you're filming (bearing in mind I've never been on any type of chromakey shoot)?

No, it is often not that obvious on a lit set. There for you should light the background and talent separately i.e. light the bg with talent (or stand-in) present but not lit and light the talent with the bg lighting turned off. That way you can more easily spot spill.

George/

[Ben Winter]

Originally Posted by George Kroonder

Hi Dan,

First I heard of this so forgive my ignorance, but how do you prevent the LED ringlight from lighting the subject as well? It's right there on the lens (as seen on the link you provided).

Sure, the keylight will be much brighter than the LED's, but doesn't this create problems in the shadows?

From what I've seen of this system the camera/LED assembly can be a good ways away from the talent and still reflect off the background, so the intensity of the LEDs on the subject is very small while the reflection off the backdrop is still strong.

[George Kroonder]

Hi Ben,

I'm sure it has it's advantages but isn't the LED ring right on the lens? The bg probably is some highly reflective surface, like the 3M Diamond Grade Reflective Sheeting you may find on traffic signs and sefety gear.

It may be an acceptable 'quick & portable' solution, just can't see it as a good general CK-solution. But I may be completely wrong and I'd love to know more.

George/

[Dan Parkes]

Hi George

Yes, this is a little off topic, so to keep it on topic I have attached a photo my client took of me and my JVC GYHD201 camera with the LED ring setup... (!)

As Ben has already mentioned, the subject is normally at such a distance that there is little to no green/blue light reflected on them at all. The LED comes with a dimmer so you can control the intesity of the LED if there was an issue with this. I also use Adobe OnLocation as a monitor and use the Vectorscope to monitor any possible spill, and I found the setup created a very good chromakey.

It is also not prohibitively expensive to buy. The basic setup can be purchased here in the UK for £400- 500. Filming corporate interviews in various European countries as I have been recently it would have paid for itself and would have been so much better than lugging extra lights and a large lastolight around!

I will be keying the interviews this week, once I get client approval, but due to its internal nature I am probably not at liberty to share a screengrab, sorry. The client is particularly sensitive about this.

Regards
Dan

[Dan Parkes]

PS

The only drawback I can state, with the JVC being 82mm, using a stepdown ring does create a vignette if shooting completely wide. However, since I was normally at least several metres from the subject and shooting head and shoulder interviews, I was zoomed in sufficiently to avoid this problem.

Dan

[Jim Andrada]

Quick question - do reflective items like eyeglasses create a problem?

[Dan Parkes]

Hi Jim

Yes, this was a concern I initially had. Several interviewees had glasses and I wondered if this might be a problem. But I found that if they are looking to an interviewer off to the side of the camera it was a never an issue, coupled with the fact that the camera is set at a reasonable distance away.

Dan

[Claude Mangold]

In 2002, when I was still TV producer we tried this system out, with the reflective bg cloth.
It worked beautifully with static subjects.very clean contours, and no spill at all if you can believe this.
Except people's eyes get tired very quickly from the glare - and even TV hosts hated his.
But efficient it was !
With subjects moving about, forget it.

[Claude Mangold]

OH, sorry, forgot to mention - we used Digibeta then

[David Scattergood]

As I'm only in the process of testing (and yet to hear exactly what the client might want) I'm building my own green screen kit. I was looking a a few hundred quid at least just for the cloth and the frame.
I earlier today sourced a huge fabric store and chose a fairly representative green (cotton - the muslin were cream/white only meaning I'd have to paint etc) a good size for a cheap price.
I'd also found a guide to making your own frames (from plastic conduit) which enables easy dismantlement and a roller to keep the cloth on (and crease free in transit). I'll let you know how I get on and post a pic :)
Due to the small width of the cloth, I'm having to create a hem down the middle:
might this be a problem for keying later on (I'll try to keep it a clean a line as possible)??
Would it be controversial to use the suggested magenta gel over the halogen/s (which I may have to use a temporary back rim lights)?

Also - the post CK key/spill remover plug ins look a little pricey, might I wrangle with Motion or FCP or are there any recommended free plug ins available?

Many thanks.

[Jim Andrada]

Claude,

one quick question. When you say "moving about" do you mean fairly extensive motion such that you'd have to pan to follow them? Would normal, sort of standing in the same spot, or sitting down and moving normally (ie picking things up, turning slightly to talk to the person next to them etc) work OK?

[David Knaggs]

Originally Posted by David Scattergood

Also - the post CK key/spill remover plug ins look a little pricey, might I wrangle with Motion or FCP or are there any recommended free plug ins available?

Hi David.

Motion gives a fairly good result. I first use the Bezier Mask Tool (garbage matte) to get rid of any extraneous parts of the frame and leave only those parts of the greenscreen that are very close to the subject. This can help in cases where the greenscreen is unevenly lit.

I then use the Primatte RT keyer, which comes supplied with Motion 3.0.2, for the keying process.

[Brian Luce]

Originally Posted by Claude Mangold

But efficient it was !
With subjects moving about, forget it.

Dealbreaker!

[Mark Silva]

Originally Posted by David Scattergood

Also - the post CK key/spill remover plug ins look a little pricey, might I wrangle with Motion or FCP or are there any recommended free plug ins available?

Many thanks.

David, if you own adobe after effects 7 or later it comes with the
Keylight keyer for free.

This plugin is VERY robust and pulls excellent keys even with
straight HDV footage.

I would definitely recommend keying in After Effects or Motion if thats
what you have. I've tested MANY plugins and I have not yet found
one that works well in FCP. The keying is ok, but not great and never
is in my experience. Doing it in a compositing app is really my only option
for good keying even for scenes with someone wearing glasses and getting that transparency just right.

[Dan Parkes]

Originally Posted by Claude Mangold

In 2002, when I was still TV producer we tried this system out, with the reflective bg cloth.
It worked beautifully with static subjects.very clean contours, and no spill at all if you can believe this.
Except people's eyes get tired very quickly from the glare - and even TV hosts hated his.
But efficient it was !
With subjects moving about, forget it.

Hi Claude

Am very curious as to the difference between static and moving objects using the LED ring technology. I didn't see any difference if the subject was moving or not and cannot see how this would affect the key. But for future reference I would be most interested to know.

Regards
Dan