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Lighting for a green screen

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Taylor Dansen

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Does anyone have any advice for a first timer lighting for a green screen shoot?
Thanks!
 
Shawn Booth said:
Light for your subject -
Click to expand...

I usually light the subject first, then the backdrop.

If you light the greenscreen first, you'll usually get problems with the foreground lighting spilling to the greenscreen, making it uneven and requiring re-adjustments of the greenscreen lights (unless there's a LOT of separation between the two).
 
No simple answer

No simple answer

There's no simple answer, but here's a few tips. I've written and sold quite a bit of software for compositing green screens footage, so I've had some experience with this. The general principle at work is that background must be as uniform in brightness and color as possible. The color of the background needs to be very saturated.

1. First light the green screen. Turn every other light off.
2. Then light the subject. The subject should be lit to match the what the background will look like in the final composite. Using a pre-visualization solution really helps. I created Veescope Live for this, but there are other solutions as well.
3. Steven Wright recommends the backdrop should be exposed at 1 f-stop below the key light.
4. Avoid using any color in the subject that is similar to the backdrop. Cyan and yellow should be avoided when shooting green screens.
5. Sharp transitions are easier to key than objects with levels of transparency, glass, curley hair, flying wispy stuff.
6. Reduce spill by moving the subject away from the backdrop. Light the subject from behind can reduce the amount of spill, as well. Pre-visualization really helps for this, as your eyes will not see the spill falling on the subject from the background.
 
If you are shooting Red, I would avoid 2k if possible. I just did a couple green screen shoots this weekend that were all 3k 48ps, lots of motion blur and fast moving subjects that keyed perfectly though.
 
Michael Ragen said:
If you are shooting Red, I would avoid 2k if possible. I just did a couple green screen shoots this weekend that were all 3k 48ps, lots of motion blur and fast moving subjects that keyed perfectly though.
Click to expand...

Can you post a few before and afters with Red?
 
BradWright said:
.
5. Sharp transitions are easier to key than objects with levels of transparency, glass, curley hair, flying wispy stuff.
QUOTE]

Hi,

When testing always do difficult subjects like smoke, glass, pouring water & fine hair. When you can make those things work well, you will have no issues in the real world.

Stephen
Click to expand...
 
If you are green screening with RED I recommend using 4K resolution, and color balancing your lights to daylight, this will reduce the noise in your shot and make the final product far easier to key.
 
Light the screen first!

Green Kino Flos for the BG if at all possible.

FG lit to PERFECTLY match the background to be keyed in. Don't forget to match the depth of field, angle of view of the lens, height & angle of the camera, etc.

Avoid FG objects that turn into green light reflecting mirrors, such as shiny leather.

Good shooting and best regards,

Leo
 
Eki Halkka said:
I see a lot of people suggest this... my preference is quite the opposite, especially for smallish studios, as i wrote earlier.

What benefits does one get for lighting the background first?
Click to expand...

There's no wrong way to do it. If you have a method that works for you, stick with it. The most important thing is that when you view the background on a waveform monitor, it is a flat thin line at 50 to 70 ire. The vectorscope should show a look like a little dot, as saturated as possible.

The mask is generated from any variation between the backdrop and the subject. In other words, any imperfections in the backdrop will degrade the quality of the mask. That's why some people light the backdrop first, because it is the most critical component of a good key.
 
Eki Halkka said:
I see a lot of people suggest this... my preference is quite the opposite, especially for smallish studios, as i wrote earlier.

What benefits does one get for lighting the background first?
Click to expand...

Hi,

None, as you will probably light a bigger area than required with more light than needed.

Stephen
 
If you are using a backlight to give your subject a little rim, I like to use a 1/8 (maybe even 1/4 max) minus green to help eliminate any green reflections the subject may pick up from the screen. Do not go overboard with the minus green.
 
Stephen Williams said:
None, as you will probably light a bigger area than required with more light than needed.
Click to expand...

That's my experience too. Not too good an idea, if one wishes to avoid green spill ;-)

Plus the fact that foreground lighting is bound to spill to BG, especially in small studios, especially when using soft light for FG... which causes the backdrop to become uneven, which leads to fixing the BG lighting, which usually causes the light levels to rise, so you need to compensate the FG... a viscious circle, if one's not wary ;-)
 
I think the order that matters most is to shoot the background PLATE first, so you know how to light your foreground actors when the time comes. Matching that lighting, camera position, etc. is the hardest part.

It was suggested to me to light the green background and the foreground scene SEPERATELY (order not important), so you turn off the one as you light the other.
 
here is example of greenscreen with R1, We shot 2k 16/9 RC36 100fps Keylight for keying

aniagreen.jpg


http://www.haasta.pl/pub/testy red/ania1.mp4
cheers!
 
Jeff Zueger said:
If you are using a backlight to give your subject a little rim, I like to use a 1/8 (maybe even 1/4 max) minus green to help eliminate any green reflections the subject may pick up from the screen. Do not go overboard with the minus green.
Click to expand...

In my experience, this can be very problematical; you can end up with a weird rim light that draws attention to the key. "Oh look at that magenta outline..."

Even worse, it really doesn't "erase" the green spill; those photons are still there.

Opinions vary, but the laws of physics don't.

Good shooting and best regards,

Leo
 
Why light the Screen first?

You should be using a waveform monitor and there should be no lights working other than the screen lights. You want it flat and somewhere around 60 IRE.

Now you can light your FG subjects with a proper level; some favor a stop over the screen, some say at the same level, others have different preferences. Certainly it's easy to do a test and determine what works best with your keyer of choice.

I find it easier to adjust my key level rather than the level of the screen lights. Perhaps others don't.

As for lighting only the part of the screen that you need, that should be obvious; in fact I try to create a large black fabric matte behind the FG subject to kill as much spill as possible.

Good shooting and best regards,

Leo
 
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