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Greenscreen on DVCAM


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#1 Jonathan Bryant

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Posted 10 November 2005 - 04:22 AM

What is the best way to light one person on a greenscreen that the client wants on DVCAM?

Camera: DSR-500,

Lights: Every Lowel light ever made with chimera softbox

Greenscreen: http://www.bhphotovi...egoryNavigation

Test Equipment: http://www.dvrack.com/

I know there are special software that can make it easier. But how can I light the person and know that any idiot and using any software could easily pull a key from the footage. And yes it has to be DV though I hope this doesn't turn into a headache.

I have heard mixed reviews on keying in DV. How do you light the backdrop perfectly even and what ire level should it be at?

Edited by johnhollywood, 10 November 2005 - 04:23 AM.

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#2 Stephen Williams

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Posted 10 November 2005 - 08:22 AM

But how can I light the person and know that any idiot and using any software could easily pull a key from the footage. And yes it has to be DV though I hope this doesn't turn into a headache.

I have heard mixed reviews on keying in DV. How do you light the backdrop perfectly even and what ire level should it be at?


Hi,

Doing a good composite requires both skill from the cameraman and the person doing the key.

Light the background as evenly as possible. Keep the talent 2 meters in front of the screen if possible. keep the amount of light on the background about the same as the key light on the actor. Some people prefer 1/2 stop overexposure on blue and 1/2 underexposure on green. You should test!
Also check the detail levels are not too high, any Black lines or white lines arround the actor will cause pain later!

Stephen
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#3 Dickson Sorensen

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Posted 10 November 2005 - 10:40 AM

Test Equipment: http://www.dvrack.com/

I know there are special software that can make it easier.


I have seen a demo of "Ultra 2" on the website you mentioned above(dvrack). I was very impressed as quality green screen with DV is tough. Check it out. They were pulling acceptable keys with marginal backgrounds.
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#4 Mitch Gross

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Posted 10 November 2005 - 11:25 AM

I always feel that half to a full stop underexposure on the greenscreen is vital. Light your screen nice & flat, set your camera's zebras to 70 ire and see what exposure you need to get the screen to zebra. If for example it is a T4, then dial the lens iris to a T5.6 to underexpose it by one stop. Now light your foreground talent until the zebras begin to show and you have properly illuminated them.

When shooting greenscreen I also like to give a little hairlight from above & back (on a dimmer for control) and don't go to extreme with my key to fill ratio unless the material really calls for it. Try to position the talent far enough away from the screen that they will not throw any shadows on it. And the further you put the camera the more you zoom in which means the smaller the size needed for the greenscreen.
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#5 Patrick Neary

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Posted 10 November 2005 - 12:46 PM

...another thing to be aware of is green spill filling your shadow areas if you are setting up in a typical small, white-ceiling and white-walled room. You can drape black duvateen, or anything really, to keep the green from bouncing all over the room.
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#6 Jonathan Bryant

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Posted 10 November 2005 - 10:01 PM

Thanks guys upon testing I got a good key in most NLEs basic greenscreen keyer plugin. Though the Serious magic Ultra 2 keyer is way better. I saw no hint of green at all and it has smooth edges too. Most of all the backlight/hairlight with the cto gel on it helped out the most.

So what is the perfect IRE level I should have on the waveform for the greenscreen?



Oh and what do you guys use for lighting the greenscreen?

We first tried one 300watt Tota above, but now I am using two 300watt Lowel Totas with umbrellas just off to the side and above (just like lighting copywork) to give it a flat even look. We have a Photoflex fabric greenscreen which I am going to try and steam tommorow before the shoot to even out the wrinkles. The greenscreen isn't perfectly flat on the waveform yet hopefully I can get it perfect tom.

Thanks again for all your ideas!
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#7 Eve Cohen

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Posted 11 November 2005 - 02:48 PM

Thanks guys upon testing I got a good key in most NLEs basic greenscreen keyer plugin. Though the Serious magic Ultra 2 keyer is way better. I saw no hint of green at all and it has smooth edges too. Most of all the backlight/hairlight with the cto gel on it helped out the most.

So what is the perfect IRE level I should have on the waveform for the greenscreen?
Oh and what do you guys use for lighting the greenscreen?

We first tried one 300watt Tota above, but now I am using two 300watt Lowel Totas with umbrellas just off to the side and above (just like lighting copywork) to give it a flat even look. We have a Photoflex fabric greenscreen which I am going to try and steam tommorow before the shoot to even out the wrinkles. The greenscreen isn't perfectly flat on the waveform yet hopefully I can get it perfect tom.

Thanks again for all your ideas!


If you can get your hands on some kinos packed with supergreen blubs (green screen blubs)...that's the best way to go. As far as the IRE level, it helps if you are using Serious Magic's DV Rack, or another program - the level on the waveform montior (as far as I've tested) was around 20 or 30.

Eve
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#8 Mark Allen

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Posted 11 November 2005 - 07:21 PM

When shooting greenscreen I also like to give a little hairlight from above & back


My company requests that this is not done for greenscreen shoots unless it is totally justified by the the location lighting. Anything that breaks the true lighting of the BG is a problem. Anything that might enhance the edge is also a problem as we are trying to blend the actors into the background.

The worst enemy of greenscreen shooting is not an uneven background and I don't think the half stop difference are even remotely in the range of one thing: spill.

Blocking out all green (including from below!!!!!!!!!! :) ) except for the green which makes for the siloutte of the actor is going to help.

Number two thing I worry about is motion and relative motion in the scene because motion blur is really hard - even harder when people are moving at different speeds though. It means you have to do a split roto and handle them separately. Usually for feature effects we are doing about 8 keys or so every shot (dividing the character into head, arms, body and then other whatever the shot needs).

Number three thing... we sometimes have problems when green gets into dark areas.... but that would be a part of the spill issue.
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#9 Jonathan Bryant

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Posted 14 November 2005 - 12:58 AM

My company requests that this is not done for greenscreen shoots unless it is totally justified by the the location lighting. Anything that breaks the true lighting of the BG is a problem. Anything that might enhance the edge is also a problem as we are trying to blend the actors into the background.

The worst enemy of greenscreen shooting is not an uneven background and I don't think the half stop difference are even remotely in the range of one thing: spill.

Blocking out all green (including from below!!!!!!!!!! :) ) except for the green which makes for the siloutte of the actor is going to help.

Number three thing... we sometimes have problems when green gets into dark areas.... but that would be a part of the spill issue.


The colored backlight help overcome green spill on the subject. Also the client commented on how it will help seperate them more from the background instead of having the subject blend in to the backgroung kinda like they were cut pasted on and flat which is what IMHO would look like without the backlight. IMHO you have to give the shot depth. Yes if the lighting in the background is coming from a different direction that your lighting on the subject that looks unatural.

I was going to use a backlight to begin with but didn't consider using a colored gel. The shot keyed alot better with the backlight and its cto gel. Some of the more oranger light spilled onto the reflector to make the fill alittle more warmer which help give his face more dimension. All in all I and our client was very pleased.

If i were to be the one keying the final shot in a nle I would add some shadow,make the background a little softer than the subject and put a transparent mask over the background to have more of a textured lighting on the background. All to give it what most chroma key shots are lacking, Depth.
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FJS International, LLC

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