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Green screen lighting conundrum 2015

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andy lewis
Green screen lighting conundrum 2015
on Jan 21, 2015 at 2:52:07 am
Last Edited By andy lewis on Jan 21, 2015 at 2:59:09 am

My turn for some green screen advice (hopefully).

We'll be filming 4 or 5 kids (up to 12 years old) dancing in front of green screen. We'll be doing this many times over 3 months.



The room is 43' by 12', the green screen will either be the treated cloth kind or some kind of vinyl. As we'll be using the setup for a while I'd rather have something with a bit of stiffness - especially as kids will be dancing on it. I remember either Mark Suszko or Todd Terry recommending painting kitchen flooring so I'm looking into that also.

My question is this: green screen at the end or along the side? Which do you think will be the harder problem - limited width for the green screen (dancing kids!) or limited space for filming and a compressed lighting setup (with possible spill problems)?

A. With a 12 foot wide green screen


or

B. With a 20 foot wide green screen


The main lights could be a couple of ARRI 650s with a 1k openface if necessary - I'd rather avoid big hot lights though with kids around so this leads to my second question. Can you see any reason why we couldn't get away with dimming the Kino 4banks on the green screen and just lighting the kids with 2 or 3 Dedolight 150watts, a Kino Diva and various reflectors and diffusers when necessary? We'll be lighting the kids to simulate daylight, indoor lighting, stage lighting - various basically. The camera is a C100 putting 4:2:2 8bit into an atamos ninja so we could probably push the iso much higher than would normally be recommended for a green screen shoot. I know, I know... simulating daylight - we've got white walls though!

In short - does green screen necessarily involve blasting the subjects with light to reduce the impact of spill? Does my way around that (dimming the green screen) sound plausible?

Thanks and this project will definitely happen - I'll post photos of the setup we go with.


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Todd Terry
Re: Green screen lighting conundrum 2015
on Jan 21, 2015 at 3:12:10 am

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



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andy lewis
Re: Green screen lighting conundrum 2015
on Jan 21, 2015 at 5:19:33 am

[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.


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Mark Suszko
Re: Green screen lighting conundrum 2015
on Jan 21, 2015 at 5:12:34 pm

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!


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Mark Suszko
Re: Green screen lighting conundrum 2015
on Jan 21, 2015 at 5:17:25 pm

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!


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andy lewis
Re: Green screen lighting conundrum 2015
on Jan 22, 2015 at 8:54:43 am
Last Edited By andy lewis on Jan 22, 2015 at 5:51:42 pm

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).


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Mark Suszko
Re: Green screen lighting conundrum 2015
on Jan 22, 2015 at 2:48:39 pm

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.


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Mark Suszko
Re: Green screen lighting conundrum 2015
on Jan 23, 2015 at 1:09:54 am

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.


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Todd Terry
Re: Green screen lighting conundrum 2015
on Jan 22, 2015 at 4:33:43 pm

[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



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andy lewis
Re: Green screen lighting conundrum 2015
on Jan 22, 2015 at 5:47:37 pm

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?


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Todd Terry
Re: Green screen lighting conundrum 2015
on Jan 22, 2015 at 6:03:52 pm

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



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Dennis Size
Re: Green screen lighting conundrum 2015
on Jan 25, 2015 at 5:32:42 am

Buy 12 cheap 4'-0" shop lights from HOME DEPOT and fit them with KINO FLO 3200 tubes. Hang them overhead and on the side walls .... leave them for the entire length of your shoot (Your time is too valuable to load-in/load-out/re-light for every shoot.

Buy matte green chromakey #VFGF262 GAM Floor, lay it in and leave it.
http://www.gamonline.com/catalog/gamfloor/index.php

Rent 2 Kinos/stands to use a front fill for each of your shoot days. MY choice would be Parabeam 400's (but 200's might be enough).
This is dance, you don't want a lot of frontlight. Sidelight and top light is what models form and is the best angle for dance.

Have fun with it.
DS



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Todd Terry
Re: Green screen lighting conundrum 2015
on Jan 25, 2015 at 5:55:23 pm
Last Edited By Todd Terry on Jan 25, 2015 at 6:01:24 pm

It's very unlike me to disagree with anything Dennis would ever say. I'll concede that Dennis is a lighting expert of the highest level... and knows at least, oh, a thousand times more about this stuff than I do.

That being said, I'll disagree with a little bit of his advice. :)

Firstly, you don't need 12 of those shop fixtures (unless you want your talent to look like they are standing on the surface of the sun). You just don't need nearly that much for such a tiny greenscreen space. I'd say four, maybe five of them, tops. Very likely two across the top and one on each side is more than enough. I regularly light a greenscreen that is just about this size, and I use three shop lights to do it... and even then as I said sometimes I only use one tube in each.

Secondly don't waste a dime on Kino tubes for these fixtures. If you were using them to shoot talent, yes... but just for greenscreen washing its totally unnecessary and would be hundreds and hundreds of dollars. Accurate color temps are virtually meaningless when you are only using them to wash the greenscreen.

Dennis' advice isn't bad, but he comes from doing very high-end projects with available budgets/resources/fixtures that I suspect would put most of our projects to shame. Some suggestions are just waaaaaay overkill unless your project is very high-end, which I suspect it isn't.

All that being said, his suggestion of permanently installing these instruments for the shoot duration is right on the money.

His flooring suggestion is also a good one. That stuff is not all that expensive when you consider what it does for you.

T2

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



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john sharaf
Re: Green screen lighting conundrum 2015
on Jan 25, 2015 at 10:42:12 pm

Late to the party as usual (I am), and I should say I "never" disagree with my friend Dennis and only "seldom" disagree with Todd, but in this case I believe we're watching an episode of the "King's New Green-screen".

The whole plan is doomed by the design criteria that 4-5 kids, and then it seems the filmmaker/dancer in addition, so five people will be dancing in a room 12' wide"! This is physically impossible.

I have 12x20' screens (blue and green) and wouldn't attempt to shoot four moving people against it. Furthermore you need additional space left and right of the screen for lighting.

The only way I could image this working would be to use all three walls in the set, but again the size constraints will limit your ability to light properly and separate the actors from the set walls.

What is it that you want to out in the composite background? Will you even be able to create a "matching" light quality that will make a convincing composite. This is a primary concern in the design of an effect like this.

Even without knowing your answer, I would suggest that you use the practical walls, and perhaps paint and/or prop them appropriately, keep them in the dark as much as possible and let the action play. Is it not the dancing that is the subject of your project?

If I were doing this and money was no object, I'd cover all three walls in LED panels and program various effects or even actual background the light the dancers at the same time (with just a touch of ceiling mounted front light.

JMHO

Cheers,

JS



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john sharaf
Re: Green screen lighting conundrum 2015
on Jan 25, 2015 at 10:45:46 pm

If I were doing this and money was no object, I'd cover all three walls in LED panels and program various effects or even actual background using the lights to back and sidelight the dancers at the same time (with just a touch of ceiling mounted front light.



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Mark Suszko
Re: Green screen lighting conundrum 2015
on Jan 26, 2015 at 12:25:59 am

Just for fun, imagine shooting three independent groups on the tiny set, one at a time.... then using masking and positioning tools, compositing them into one large group on a synthetically WIDE artificial set. Using the song and beats for synch.


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andy lewis
Re: Green screen lighting conundrum 2015
on Jan 27, 2015 at 3:02:52 am
Last Edited By andy lewis on Jan 27, 2015 at 3:08:36 am

"The whole plan is doomed by the design criteria that 4-5 kids, and then it seems the filmmaker/dancer in addition, so five people will be dancing in a room 12' wide"! This is physically impossible. "

"Just for fun, imagine shooting three independent groups on the tiny set, one at a time...."

The kids are aged 8-12 (grouped by age). There will be 4 or 5 of them but no filmmaker in addition (I'm not really going to paint myself blue and join them, tempted as I am!). We can choreograph specifically for the small space so tight groups should (I hope) work. The songs are 2 minutes long so we can film them multiple times. We can split the kids into 2 groups to comp later, and maybe even film them individually for lip-sync close ups. The songs are insanely catchy - they will haunt my dreams for years.

Dennis, that GAM floor stuff is very interesting. Does it have enough rigidity to work as a cyc on its own? Or would it need curved support underneath? I'm assuming the latter as it squeegees on, but it would save a lot of time and hassle if it will curve smoothly from wall to floor.

"Rent 2 Kinos/stands to use a front fill for each of your shoot days. MY choice would be Parabeam 400's (but 200's might be enough).
This is dance, you don't want a lot of frontlight. Sidelight and top light is what models form and is the best angle for dance."

We'll hopefully have 2 Kinos for front fill, probably not parabeams though. What would you use for side lights? We'll have access to 3 x 150 watt Dedolights but I'm assuming they won't do very much - although we can use one as a spot for individual close ups. And having said that, those Dedo 150s put out way more light than I expected. And of course when I say side light, I mean the lights will be against the wall, a couple of feet in front of the dancers. So diagonal light.

Oh I've also got a colour-variable LED that I'll mount high above the green screen to add a touch of magenta backlight.


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Mark Suszko
Re: Green screen lighting conundrum 2015
on Jan 27, 2015 at 3:15:43 am

I have found that I have to turn on my camera's clear-scan feature to "dial-out" a flicker created by my LED PAR can light.


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Dennis Size
Re: Green screen lighting conundrum 2015
on Jan 27, 2015 at 6:59:45 am

ANDY ..... You can NOT use GAM FLOOR to create a curve .... but if you have a hard curve you can use it to cover the curve. Think of GAM FLOOR as "contact paper".
Regarding my excessive (???)use of shop lights (12), I was actually being very conservative. I only want you to use the 12 shop lights, NOTHING ELSE. Stop thinking about PARs and Dedos. I wouldn't even use any Kino frontlight (and would only keep the Parabeams as a CYA). If I did use them, they would be as "footlights".
I'll clarify:
+ use 4 @ 4'-0" from overhead (2 in the downstage "in 1" position, 2 in the upstage "in 2" position)
+ use 4 @ 4'-0" mounted on the stage left wall -- 2 in the downstage "in 1" position (one low, about 6" off the floor, one above it), 2 in the upstage "in 2" position. THIS IS YOUR SIDELIGHT from stage left (camera right).
+ use 4 @ 4'-0" mounted on the stage right wall -- 2 in the downstage "in 1" postion (one high, one low underneath it and about 6" off the floor), 2 in the upstage "in 2" position. THIS IS YOUR SIDELIGHT from stage right (camera left).

As I said earlier, lighting dance is all about modeling and enhancing the 3 dimensionality. The sidelight is VERY important -- and essential. I'm saying to ONLY light your talent AND THE GREENSCREEN with these 12 lights.
My priority would probably be the sidelight. Those 8 fixtures are KEY lights.
The 4 overhead fixtures are essentially to fill in the greenscreen and help separate your dancers.
Think of your little box at the end of the room as a refrigerator .... open the door (turn on the camera) and reveal the contents -- in an all encompassing wash of light.
As for the Kino frontlights ... use them IF -- and only IF -- the shadows on the front of the dancers bothers someone's parents. But even then argue for NO frontlight. If you must use it do it from the footlight angle.
I repeat .... have fun with this, and don't treat it like it's an interview with some CEO.
DS



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Bob Cole
Re: Green screen lighting conundrum 2015
on Jan 27, 2015 at 2:22:52 pm

Change the room.

The only good thing is that it is deep. It's not wide enough, though. Your dancers will not even have 12' in which to dance. They will have to be far enough away from the green screen so that it doesn't in essence become a light source on them, creating troublesome edges for your keying. It's been too long since geometry class for me to give you a number, but I'm guessing your "stage" will be about 8' wide tops.

Thanks for the post - anytime someone can get responses from the people who've weighed in already, I learn something.

Bob C.


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andy lewis
Re: Green screen lighting conundrum 2015
on Jan 27, 2015 at 5:27:22 pm
Last Edited By andy lewis on Jan 27, 2015 at 5:42:17 pm

"I was actually being very conservative. I only want you to use the 12 shop lights, NOTHING ELSE." Ha! OK thanks, I didn't get that.

"Think of your little box at the end of the room as a refrigerator .... open the door (turn on the camera) and reveal the contents -- in an all encompassing wash of light." Lovely description. I once filmed something from inside a fridge (not joking). I didn't appreciate how easy my life was back then.

"The only good thing is that it is deep. It's not wide enough, though"
I'm in Hong Kong and rent is astronomical here. The only places we found with more space were either way outside the budget or really grotty - fine for us, but not for filming kids. We tried photography studios but 12 foot seems to be a standard width here. Every (affordable) studio has a 12 foot wide cyclo with a foot of space either side. That would have given us a bit more room but we would have had to set up the green screen and take it down again 12 times.

We can use the length of the room to our advantage though, speaking of geometry. We can put the cameras far back and go for longer focal lengths to flatten perspective. I'll test it this weekend. A 70-200 on a super 35 sensor should give us enough reach. I'm hoping we can get 8 to 9 feet of useable width. I think it will be fine for the younger kids. For the older kids, if it's not working, we will have to split the groups and comp them together in post.


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