Green screen lighting conundrum 2015

[Todd Terry]

Oh I think you’d definitely want your greenscreen at the end. I’m assuming you’ll want a full-length head-to-toe view of your dancers, and if you put the screen on the long wall by the time you get any separation from the talent to the greenscreen you’ll they will be way close to the camera, even if you’re backed up right against the wall.

I wouldn’t even consider the long wall as the screen wall, not for a second.

And yes, it was Mark who mentioned the vinyl flooring. I haven’t tried that, but I know Mark has found it works well. He’s the president of the Paint-the-back-of-Vinyl-Flooring Fan Club (the “Congoleum Cartel”), although I’ve often wondered if that doesn’t cut into his duties as head of the LRFOTSHILL* Organization.

* “Last Remaining Fans Of Those Scorching Hot Infernal Lowel Lights”, members affectionately known as “The Blisters”

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com

[Andy Lewis]

[Todd Terry] ” even if you’re backed up right against the wall.
“

Thanks for that. And yes, backed up against the wall is exactly where I didn’t want to end up. Side-on it is.

What do you think about dimming the Kinos for a (fairly) minimal lighting setup on the kids?

I thought the Congoleum Cartel had already split into warring factions but perhaps the peacekeeping missions have sorted it all out now.

[Mark Suszko]

We don’t know anything about the specific choreography, but having the space deeper rather than wide, allows for some fun moves by the dancers in the z-axis, and you may be able to do things with tight depth of field control that would be aesthetically pleasing. You’d also get more separation distance between wall and cast, and thus less spill problems.

Kids dancing on paper rolls is going to tear up the paper very quickly. And it may slip and slide.

Cloth could work, it can be washed or sewn if dirtied or torn, and be rolled up so the room can be put to other uses in-between green screen sessions. If going with cloth, I might think about painting the actual floor and making a cove at the floor/cloth joint.

The sheet vinyl flooring route is VERY rugged, and also can be rolled-up for storage, but has the downside of being heavy in large quantities. Which isn’t a big deal if you can hang the material properly. A modified idea would be to buy cheap 2-foot or 4-foot square linoleum tiles and paint them on one side only, and lay them without glue for temp use, reducing the amount of the sheet vinyl to just the wall and the amount needed to curve onto the floor.. You’d want to keep a pint of the green paint around for repairs just in case, but I’d say save up a gallon, so you can also paint some props like green cubes, which will come in handy later…

Try a local Habitat For Humanity “Re-Store” as a cheap vinyl floor source. What you want is something without a textured reverse or “felt” side. It needs to be primed with KILZ brand LATEX water-based primer, then any chromakey paint will work on it, even the stuff you mix yourself at ACE.

Considering your dancers are kids and thus shorter than adults, it looks like you may just have enough overhead space to run a strip of PARS with diffusion, or long flo tube lighting, to light the green. That would help you get maximum width from the narrow space.

Good luck with it!

[Mark Suszko]

A practical consideration occurs to me: with kids, you never know how they are going to dress, even when you send notes home in advance. You’ll really have to harp on the “don’t wear green” dress code thing.

Or…

For a lot of fun, have them ALL wear green on purpose, or better, blue, and do 2 stages of chromakey: one for the green B.G. and one for their blue outfits.
Far OUT, man!

[Andy Lewis]

Thanks Mark. That’s a really good point about the z-axis. As soon as I read that, I had a very clear mental image of choreography with some depth and differential focus. Great suggestion.

“Considering your dancers are kids and thus shorter than adults, it looks like you may just have enough overhead space to run a strip of PARs with diffusion, or long flo tube lighting, to light the green”

Ceiling-mounting the lights for the green screen probably makes sense. I’m nervous about it though. Even though it’s probably safer than lights on stands. The thought of heavy and/or hot lights hanging overhead with children around makes me shudder. I’ll look into it and make enquiries about whether or not we can drill big holes in those ridges on the ceiling and if they will take the weight.

We’ve budgeted for 2 x Kino 4banks (and might even get the green lamps to make the neighbours jealous) but it is a stretch. Do you think they will be worth it over cheapo CFL bulb units in softboxes? I’d be nervous of PARS cos of weight and heat, but I suppose if they’re securely mounted…

I never considered 2-stage chromakey. I could paint myself blue and join them on the dancefloor – then I can make one version without me (for the client) and one with me (for the world).

[Mark Suszko]

Hardware stores sell inexpensive clear plastic safety cover tubing for fluorescent lighting, which will contain all the shards if the light gets hit and breaks inside the sleeve. In some schools these may already be mandatory.

Those are structural beams overhead. Generally difficult to get permission to mess with those in terms of making holes. But you could certainly use c-clamps and extending tension poles up there.

[Todd Terry]

[andy lewis] “We’ve budgeted for 2 x Kino 4banks (and might even get the green lamps to make the neighbours jealous) but it is a stretch. Do you think they will be worth it over cheapo CFL bulb units in softboxes?”

If I were in your shoes, I would definitely go with 4′ flos to light the greenscreen, a much better choice over softboxes.

You said this would be doing this many times over three months, though. If I would in your shoes I wouldn’t burn up my budget on Kinos, though (as much as I love Kinos… big fan here). I’d use 15-buck shop lights from Home Depot or Lowes.

Here’s a post of mine from a previous thread…

https://forums.creativecow.net/readpost/47/860645

You might want to read the whole thread, too. For probably less than a hundred bucks you could rig out several of these (and you would own them… could even leave them in place if this room is dedicated for the 3-month period). In a room that size I’ll probably use four two-bank fixtures… two horizontally across the top and one vertically on each side.

I try not to be a lighting snob… I very much like good and “proper” instruments, and we have a decent arsenal of very nice fixtures. But for something like greenscreen work the shoplights are my go-to fixtures. They work like a charm and are throw-away cheap.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com

[Andy Lewis]

Yes, I love the good stuff too but cheap has a beauty all its own.
And I like the idea of using 4 x 2-bank fixtures, that makes a lot of sense. The main worry I have about using cheap fluorescents is the possibility of colour phasing and banding that isn’t fixable with frame rate / shutter speed. I know it’s only lighting the green screen but I imagine that pulsing, wavey spill is much harder to deal with than consistent, steady spill.

A theory: The worst fluorescent phasing problems are caused by ‘dirty’ electricity – so the lights aren’t cycling at exactly 50/60hz, right? So if the fluorescent fixtures currently in the building don’t cause visible in-camera banding, then the electricity is fine and we will be ok with the cheap lamps. Does that sound right?

Talking of spill – it’s slightly unnerving to me that however hard I try to create separation, to reduce the spill from the green screen, the cyc is going to go under the feet of of the dancers. Isn’t there going to be green everywhere?

[Todd Terry]

Phasing can be an issue, but it’s a cheap trial-and-error to grab one of these shop fixtures and run a test.

I have seen some phasing with mine, and some not… and it was always predictable and exactly repeatable.

I used my shop lights for greenscreen washing for a 16mm shoot once where I DID see phasing. Actually, I didn’t even see it myself, but it wasn’t noticed until the film was telecined. When the film was either being fast forwarded or rewound through the Spirit the colorist said “Hey, it’s phasing, I didn’t even notice that.” What we saw (only at fast motion) was an ever-so-slight increase and decrease of the intensity of the illumination on the greenscreen. Each phase took about 15 seconds to make its loop, and it was just barely a change. It was so minute and so slow that at normal speed you couldn’t even see it, and it did not affect keying. My 16mm camera had a non-variable (fixed) 180° shutter.

I never had any noticeable phasing when shooting 35mm film using the shop lights. My 35mm camera has a 170° fixed shutter.

I’ve never had any phasing at all when shooting video… and typically shoot 24p (23.976fps) with a 1/48th (180°) shutter. If I ever did detect any phasing, I’m sure I could click over to clearscan mode and dial it right out with a more precise shutter speed.

It probably depends on the combination of the ballast in the fixture, and how clean your power is… but I’ve never had any issues.

I’ve also always found the 2-bank four footers to be more than bright enough. In fact, our stage space is fairly small so sometimes I’ve found them to be overkill, and had to use them with only one tube in them. We buy both daylight and tungsten temp tubes, readily available at the hardware store. For greenscreen work a high CRI is not critical and their color temps are just fine.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com

[Mark Suszko]

Spill often happens when people panic and over-light the green so hard it blazes. It’s not really about how bright the green is but how SATURATED and EVEN it is.