Lighting for greenscreen

[Jason Rouleau]

Hey guys,

I've just opened up a magnificient studio and am offering to my clients small green screening services. Its just going to be a 12x24 screen and I am blessed with a very high ceiling. I'm looking on making a permanent light installation for quick shooting (mostly just people talking in front of a green screen). So I was thinking of rigging up a bar that can come up and down and from which I can suspend lights (kinda like a grid, but with just 1 bar).

Now, he's the catch. I have a fairly good budget, so I need to find lights for this baby. I was thinking 2x 1k Fresnels (with diffusers or soft boxes) hanging from the ceiling to evenly light the green screen and smaller lights to light the subjects.

I haven't shopped around for lights in a LONG time, so I'm looking for some help here.

1 - Are 2x1k lights enough you think? will they light evenly? If not, what would you recommend (I'm ready to spend between 2k$-5k$ for these lights)

2 - Can you recommend any good suppliers for lights? (I would undoubtedly need C-clamps to hang those suckers too)

Oh and they have to be able to supply to Canada! :P

I thank you all in advance!

Jay

[Rob Lohman]

Just to jump-start this thread a bit, if I remember correctly the main things
to achieve is uniform lighting and seperating your foreground from the back-
ground.

The first would suggest you need a row/bank of lights to flood the screen.
The second would suggest you have some extra lights that kick from the
back towards the front (at an angle) to illuminate the subject from the
back (to seperate it).

I've checked my lighting books and "Placing Shadows, second edition,
Chuck B. Gloman & tom Letourneau" has this to say (on page 174):

Lighting is also extremely important. It must be flat. If too much shadow is thrown on the chroma key background, that will make it darker and harder to key. Everything must remain even. Backlighting is not as critical in this type of setup because the background will be eliminated.

On page 175:

There are two crucial elements involved when you are lighting foregrounds for convincing matting. They are backlighting and side lighting. Side lighting is particularly crucial because often when you look at someone standing in front of a blue sceen, you will notice light bouncing off the sceen onto the talent .... Sidelight sources can be soft or specular in nature, depending on the look you are trying to match. Fresnels might be used when matching the look of a background that was shot ouside on a sunny day, but softlights might be approriate if the background material was shot in a fluorescent lit office environment or outside on an overcast day.

Some other points they make:

- Most important thing about lighting the blue background is consistency in terms of evenness and color temperature

- Don't use dimmers (color temperature shift)

- Cyc strips are the easiest instruments to use (they produce an even wash of light)

- If you fully need to key (ie, the floor also has blue/green material) don't light it straight down. A polarizing filter (on the camera) is highly recommended to remove glare from the floor

- The ratio of light on the background screen to the foreground subject should be roughly 1 to 1 when measured with an incident light meter.

That's about it I think... Hope this helps some

[Frank Feijen]

Intresting and thanks.

As an editor i see quite some bluekeys, and the biggest (most frequent) problem is the light that bounces from the screen to the sides of the actor.

Can this be completely countered by the use of sidelight?

[Rob Lohman]

According to the book that is the primary function of that sidelight indeed.
However, I've never actually gotten to the point of shooting green/blue
screen so I have no idea. I was merely quoting what the book says :)

Hopefully some other people with experience will join in!

[Jason Rouleau]

Awesome answer!

The only thing I'm not quite sure about is : What are Cyc Stripes? Do you mean neon tubes?

[Matt Ockenfels]

Frank,

In my experience, the biggest reason for green or blue light spill on the subject is that the subject is too close to to the screen. However, if you're working with painted cyc AND floor there's no way to avoid this.

Side lights can work OK, as long as the lighting effect is consistant with lighting in the background composite. I've also seen backlights with colored gels (colored opposite the matte color) used with some success.

Jason, here's an example of cyc lights:

http://www.ultralightmfgco.com/sales...yc&state=sales

Cheers,

-Matt

[Jason Rouleau]

Well I took a look at the CYC lights and they look pretty affordable and good. I bet they're great at casting even lighting. now the only question I have left is : how many do I get? I have a 12x24 canvas. I was figuring maybe a 10 or 12 CYC light. But would that be overkill?

I've never worked with CYC lights. Are they easy to install? Anyone have experience with them?

[Nate Ford]

yeah a pink filter on your back/side light can help if you can get away with it (keep it off the greescreen though.) maybe like a 1/4 minus green (for color correcting fluorescents) would kill the green spill without reading too pink.

[Jacques Mersereau]

Originally Posted by Jason Rouleau

Well I took a look at the CYC lights and they look pretty affordable and good. I bet they're great at casting even lighting.
<EDIT>
I've never worked with CYC lights. Are they easy to install? Anyone have experience with them?

Having done quite a bit of blue and greenscreen work I personally would
AVOID using cyc lights for this kind of work. (I have lots of them.)

WHY? Because each light produces a HOT SPOT.
What that means is that the camera will see
a GRADATION formed out of each light. Diffusion will help, BUT
not completely, and it wears out. Tungsten lights also produce lots of HEAT
and draw a lot of power.

If you have a budget, look into florescent lighting which draws less power,
runs cooler and provides much smoother light.

[Jason Rouleau]

Any advice on where I could get them ? (website?)

[Nate Ford]

b&h has plenty-
http://www.bhphotovideo.com/bnh/cont...ren&Q=&ci=1167
i've not used them for international shipping before, but i'm sure they can take care of you. the upcoming arri stuff looks really nice.

[Jason Rouleau]

Great site and the fluorescents make sense since that is what I used last time I shot greenscreen in Toronto.

Now from what I gather, I should use a NON dimming fluorescent.

I also figure a 220 WATT lamp should be powerful enough to light my 12x24 matte.

I of course need a hanging mount. And probably some eggcrates to diffuse the light a bit.

Now here is the question, which one should I get? hehe

The Arri Studio Cool 4?
A Desisti 4 Tube?
A Lowel-E Studio 6 with a 40 degree honeycomb grid
Or simply Kino Flos?


Oh and for greenscreening, should I use a 5600 Kelvin light (daylight)? or another type of tube?


Man I have alot of questions :p

Cheers!

[Jacques Mersereau]

>>Now from what I gather, I should use a NON dimming fluorescent.

They are a lot cheaper. It is rare that you need a screen dimmed in
my experience . . . as in I've never needed less light.

>>>I also figure a 220 WATT lamp should be powerful enough to light my 12x24 matte.

One? I would think you would need/want as many as you can line up
end to end. Remember, you want to somewhat match the exposure of
both talent and screen. IOW, a brightly lighted person and a dimly lighted
screen will not give you 'effortless' results.

>>>I of course need a hanging mount. And probably some eggcrates to
>>>diffuse the light a bit.

Yes, you'll want to hang them, but most lights come with at
least a yoke so you can use inexpensive pipe clamps. I get mine from www.proadv.com

I don't think you *need* egg crates. First, they are EXPENSIVE and are
generally used to control (read: focus) soft light from spilling all over
the place. As long as the screen lights don't directly spill heavily on your
subject (and they should NOT unless you messed it up) you won't
need egg crates.

>>>Now here is the question, which one should I get? hehe

The Arri Studio Cool 4?
A Desisti 4 Tube?
A Lowel-E Studio 6 with a 40 degree honeycomb grid
Or simply Kino Flos?

All of the above are good choices. I don't think you can go wrong with
any of the above.


>>>Oh and for greenscreening, should I use a 5600 Kelvin light (daylight)? >>>or another type of tube?

Is your screen painted blue (or green) or is it white? Not that it matters
that much because what you want is simply smooth lighting. Good software
will pull the key from almost color you select. Higher color temp light will
produce a different (resulting) color on any background than 3200K,
but most keyers don't mind. You usually 'tell' them the color to use.

>>>Man I have alot of questions :p

Keep 'em coming. That's what this forum is all about :)

[Shane Matich]

Interesting that people say dont use dimmers, because the reality in big budget "green screen" films is quite the opposite...

Last month i prepped sixty 32amp hp12 dimmers for just one sound stage on superman returns. Green screen Movies like matrix, stealth, superman returns are also using huge banks of ordinary rock'n roll PAR cans with halogen bulbs & large silks in front. The Matrix sequels used over 2,500 par cans [1000w].

With studio setups it pays to use dimmer systems with dmx control from a lighting desk, even for cyc's and fluro's. I would recommend you have 3 truss runs. One in front of the talent with a light on either side of center, one truss behind the talent with light on either side of center, and one lighting truss above the green screen with 3 lights to light the screen.

Run all cable from lights to the one side and then run it upstage to a 12 channel dimmer[$500-1000]. With your basic & every easy to use 12 channel lighting desk[$100-200] you can grap a coffee and sit down & relax. Each channel on the desk controls one light, so creating the key, fill & back light loooks is easy. The dimmmer and desk do all the leg work for you.

The cheapest option for your lights is to buy second hand quality theatre fixture [fresnals] they will come with clamps to hang off bars. Theatre lights are designed to be used in studios & for the light to be controlable. Expect to pay around $100 - $ 300each for 1000w fresnals.

On a sidenote, have you checked what the power supply situation is?

[Stephanie Wilson]

Just a note about this incredible forum and the incredible people who post. We would have had to pay a fortune in film/video school to obtain the knowledge that Shane just shared with us for free.

Thank you SO MUCH Shane. Just such amazingly helpful information and so kind of you to take the time to share it with the rest of us.

Many, many "miracles" coming to you soon friend. Just try and recognize them as such.

All the best,

Stephanie