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Green/Blue Screen Lighting


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#1 stephen lamb

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Posted 14 September 2005 - 12:10 PM

Hi All,
I am going to try out a small green/blue screen test (haven't decided yet on which color) and after doing some research i think i have an idea of how to light it. I don't have to money to rent specialized flourescent tubes, so im going to get commercial daylight tubes, or kinoflos, and filter them. My question is which gels to use to filter them. I have found several possibilities and i was wondering if someone could tell me which would work best. For blue screen work i have found the following, LEE "just blue" #79, LEE "true blue" #196 and Rosco SuperGel "Primary Blue" #80. For green screen i have found: LEE "Primary Green" #139, Rosco SuperGel "Priamary Green" # 91, and Rosco SuperGel "chromagreen" #389. What do you guys think? Any other tips/suggestions, the scene itself will be a man walking towards the camera with backing behind him, and thats it. In post i am going to add in a CG hallway. Thanks for your help guys,
Steve
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#2 Stephen Williams

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Posted 14 September 2005 - 12:44 PM

Hi All,
I am going to try out a small green/blue screen test (haven't decided yet on which color) and after doing some research i think i have an idea of how to light it.  I don't have to money to rent specialized flourescent tubes, so im going to get commercial daylight tubes, or kinoflos, and filter them.  My question is which gels to use to filter them.  I have found several possibilities and i was wondering if someone could tell me which would work best.  For blue screen work i have found the following,  LEE "just blue" #79, LEE "true blue" #196 and Rosco SuperGel "Primary Blue" #80.  For green screen i have found:  LEE "Primary Green" #139, Rosco SuperGel "Priamary Green" # 91, and Rosco SuperGel "chromagreen" #389.    What do you guys think?  Any other tips/suggestions, the scene itself will be a man walking towards the camera with backing behind him, and thats it.  In post i am going to add in a CG hallway.  Thanks for your help guys,
Steve

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Hi,

It might be easier to use a blue or green background and just use normal lights. If your are using domestic flourescent on video you should be ok. If you can get minus green gell so much the better as they will have a green spike.

Stephen
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#3 Gordon Highland

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Posted 14 September 2005 - 12:50 PM

If you're shooting this on video, I'd recommend using a green screen. I don't think you're going to have to filter your lights to get a good key, but if so, converting daylight to tungsten would mean an orange gel, or regular fluoro to tunsten a magenta one (aka "minus green"). You don't even have to use fluoros, they're just convenient and even. You could point regular ole tungstens at them and just be sure it's totally even. These could be parts of your test. Don't overexpose the background, it should be nice and saturated. If you have a waveform monitor, around 40 IRE should give you a good level here.

Watch the light falloff on the corners. Get plenty of distance between the man and the background (don't let spill light reflect on him). Backlight/rimlight on the subject can be helpful, but can also look fake in these situations. Are you doing a rack focus as he approaches camera? Some keying software has trouble with blurs ("Keylight" handles them well). This could be another part of your test. Don't be afraid to experiment!
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#4 stephen lamb

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Posted 14 September 2005 - 02:59 PM

Hey All,
Thanks for the tips so far, i forgot to add that i will be shooting on film, most likely S16mm. Does that change your lighting advice at all?
Thanks!
Steve
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#5 Stephen Williams

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Posted 14 September 2005 - 03:25 PM

Hey All,
Thanks for the tips so far, i forgot to add that i will be shooting on film, most likely S16mm.  Does that change your lighting advice at all?
Thanks!
Steve

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Hi,

Just take more care with film, its expensive!

Stephen
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#6 Paul Bruening

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Posted 15 September 2005 - 10:10 PM

Hey now,

Whoever provides the screen or paint can tell you what's the best gelling for each light type. The trick with the green screen is that they're designed to put that green within a specific color band that film doesn't see so well. It's sort of like a "hole" in film's color range. Video doesn't have the same "hole" as film, so, let the screen or paint supplier know what you're shooting with as well.
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#7 Michael Cathcart

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Posted 16 September 2005 - 12:38 AM

Hey Steve,

One thing that I have heard works great for Green/Blue screen lighting is to back light the screen, the problem with front lighting (especially for video but I suppose film aswell) is that if any part of the screen is in shadow it just makes it that much harder to key out, believe I've had experience trying and its a pain in the rear.
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#8 Dimitrios Koukas

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Posted 16 September 2005 - 07:23 AM

Hi All,
I am going to try out a small green/blue screen test (haven't decided yet on which color) and after doing some research i think i have an idea of how to light it.  I don't have to money to rent specialized flourescent tubes, so im going to get commercial daylight tubes, or kinoflos, and filter them.  My question is which gels to use to filter them.  I have found several possibilities and i was wondering if someone could tell me which would work best.  For blue screen work i have found the following,  LEE "just blue" #79, LEE "true blue" #196 and Rosco SuperGel "Primary Blue" #80.  For green screen i have found:  LEE "Primary Green" #139, Rosco SuperGel "Priamary Green" # 91, and Rosco SuperGel "chromagreen" #389.    What do you guys think?  Any other tips/suggestions, the scene itself will be a man walking towards the camera with backing behind him, and thats it.  In post i am going to add in a CG hallway.  Thanks for your help guys,
Steve

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Use a rosco paint or similar that has excactly the colour a green or blue screen needs,
keep your subject away from the background, it is a good advise.
That means that you have to make your background bigger, so consider this you should talk with the production, If you are going on tungsten film, I suggest that you use tungsten lights for the backround, with some 1/4 or 1/2 C.T.B. , try to lit it even, carefull that your lights do not overlap so much , wich will give u a hot spot.
Any light that u add, in the background, will overlap with another, so this will be a pain if u don't be carefull.
Use flags on your lights to avoid blue colour from the gelled light to fall on your subject,in case you are doing a green screen then either add some plus green gels or some CalColour green gells.
Light your subject with same temperature lights as your film, and only correct the background.
One other thing that u maybe want to be aware of, is becarefull that the light form your subject falls too much on the background.
Gool luck, I hope I have helped.
Dimitrios
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#9 Dimitrios Koukas

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Posted 16 September 2005 - 07:29 AM

Hi All,
I am going to try out a small green/blue screen test (haven't decided yet on which color) and after doing some research i think i have an idea of how to light it.  I don't have to money to rent specialized flourescent tubes, so im going to get commercial daylight tubes, or kinoflos, and filter them.  My question is which gels to use to filter them.  I have found several possibilities and i was wondering if someone could tell me which would work best.  For blue screen work i have found the following,  LEE "just blue" #79, LEE "true blue" #196 and Rosco SuperGel "Primary Blue" #80.  For green screen i have found:  LEE "Primary Green" #139, Rosco SuperGel "Priamary Green" # 91, and Rosco SuperGel "chromagreen" #389.    What do you guys think?  Any other tips/suggestions, the scene itself will be a man walking towards the camera with backing behind him, and thats it.  In post i am going to add in a CG hallway.  Thanks for your help guys,
Steve

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U are saying VFX, do you want a 3d moving background?
Then u need track balls or just some trackers for the guy in the post. Ask him too.
Dimitrios
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#10 Stephen Williams

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Posted 16 September 2005 - 12:58 PM

The trick with the green screen is that they're designed to put that green within a specific color band that film doesn't see so well. It's sort of like a "hole" in film's color range. Video doesn't have the same "hole" as film, so, let the screen or paint supplier know what you're shooting with as well.

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Hi,

I am not sure I agree!

The film has to see the green otherwise there is no was to pull a matt! Its the same for a digital or optical finish.

Stephen
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#11 stephen lamb

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Posted 16 September 2005 - 05:22 PM

Hey all,
thanks for continuing to give input, i appreciate it!
Quick question, Stephen Williams, i am trying to decide between blue or green screen. I believe the acter will be in dark colors, probably black, he is caucasion. I have access to the same size backing in either color...not very big unfortunetly, but except for an excerpt from the ASC manual that says blue screens generally work better in post for caucasion actors, i haven't seen much saying one or the other. Thanks!
Steve
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#12 Stephen Williams

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Posted 17 September 2005 - 05:08 AM

Hey all,
thanks for continuing to give input, i appreciate it!
Quick question, Stephen Williams, i am trying to decide between blue or green screen.  I believe the acter will be in dark colors, probably black, he is caucasion.  I have access to the same size backing in either color...not very big unfortunetly, but except for an excerpt from the ASC manual that says blue screens generally work better in post for caucasion actors, i haven't seen much saying one or the other.  Thanks!
Steve

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Hi,

What is the color of the background shot? If it has more blue go with blue, if it has more gren go with green.
I have tested the color thing constantly over the last 15 years, compositors always tell me what they prefer. The next time I shoot 1 take against the color not recomended. Almost every time the results are identical! Its more of a compositors excuse when they don't have full control of their software!

Stephen
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#13 stephen lamb

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Posted 17 September 2005 - 04:03 PM

Stephen,
You seem pretty savvy in the green/blue screen process, and i really appreciate all your help so far. more questions though of course, Do you know of any good website forums that are oriented more towards the CG/VFX part of the process? Thanks!
Steve
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#14 Stephen Williams

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Posted 18 September 2005 - 06:35 AM

Stephen,
You seem pretty savvy in the green/blue screen process, and i really appreciate all your help so far.  more questions though of course, Do you know of any good website forums that are oriented more towards the CG/VFX part of the process?  Thanks!
Steve

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Hi,

For compositing and VFX, CML is a great resource.

http://www.cinematography.net/

Stephen
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#15 Dimitrios Koukas

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Posted 18 September 2005 - 06:57 AM

Stephen,
You seem pretty savvy in the green/blue screen process, and i really appreciate all your help so far.  more questions though of course, Do you know of any good website forums that are oriented more towards the CG/VFX part of the process?  Thanks!
Steve

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Try to now what are the colours the actor is wearing, not only the skin colour, do you have close ups and he has blue eyes?
Or green eyes?
Take care all the details.
Dimitrios
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#16 Stephen Williams

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Posted 18 September 2005 - 09:15 AM

Try to now what are the colours the actor is wearing, not only the skin colour, do you have close ups and he has blue eyes?
Or green eyes?
Take care all the details.
Dimitrios

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Hi,

I am not bothered by eye color at all!
Superman was shot on a blue background and his clothes were also blue but a different blue!
I have many times composited both water and smoke shot against blue or green, indeed that what I use to test new systems!

Stephen
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#17 stephen lamb

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Posted 18 September 2005 - 12:29 PM

Hey guys,
once again, thanks for the replies. Stephen, i checked out that website and it is terrific, three great threads already just about lighting backing. neat stuff, eye color, i had read that before but eh, forgot about that. thanks for the reminder, it can become easy to overlook details, thanks guys!
Steve
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#18 Stephen Williams

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Posted 18 September 2005 - 01:06 PM

eye color,

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Hi,

The reason I don't worry about eye color is that usually there is nothing like enough saturation in the eye's to cause a key issue. In the rare situation when they do its very easy to matt out!

Stephen
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#19 Dimitrios Koukas

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Posted 21 September 2005 - 04:18 AM

Hi,

The reason I don't worry about eye color is that usually there is nothing like enough saturation in the eye's to cause a key issue. In the rare situation when they do its very easy to matt out!

Stephen

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Stephen,
The reason I am trying to alert for the details is that you and me maybe know how to do it, but what if someone doesn't?
And yes u were right, I believe I ve gonne too far ;-).
And another thing. Rosco paint comes in different colours , if you have tables or chairs on the set that you want them to be matt out in the post, then Rosco suggests u use a darker blue on the top surfaces and the lighter one for the surfaces that facing the lense.
I ve done many Green screens Blue or white ones even black screens sometimes, depends on the subject.Since 1988 that I ve started working the compositing technology have changed a lot, so there are some fewer things to worry about, wich is good.

Dimitrios

Edited by Dimitrios Koukas, 21 September 2005 - 04:18 AM.

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#20 Stephen Williams

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Posted 21 September 2005 - 04:29 AM

And another thing. Rosco paint comes in different colours , if you have tables or chairs on the set that you want them to be matt out in the post, then Rosco suggests u use a darker blue on the top surfaces and the lighter one for the surfaces that facing the lense.


Dimitrios

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Hi,

Thats a good point but most producers eyes start to roll when you ask for 2 shades of Blue Screen paint. Very important if there is a lot of light from above!

Cheers,

Stephen
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