Chromakey : Green Halo

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Chromakey : Green Halo

Post  aimc on Sun Oct 05, 2008 10:27 am

Hi there Mark - thanks for your excellent DVDs - I have them all and am learning a lot from them!

I'm currently trying to get Chromakey working and am having a little difficulty with the dreaded green halo effect ...

I am shooting 6 - 8 feet from the screen and don't think its a reflection problem, although
admittedly my subject lighting is still a work in progress and I am mixing daylight lighting (for the screen only) with Halogen. I have tried White Balancing for both sets of light and the only thing that changes is I get a bluish halo if I balance for halogen, and green if I balance for daylight (using a white board and the cameras manual WB mode). Although I know mixing light types is bad, I figured I would get away with it if I separated the screen and the subject lighting. In any case, even when I used all halogen although it was dim I got similar results.

My worry is that this may be a shortcoming of my camera - its a Canon Elura so a cheap MiniDV model, and I am using Vegas with similar settings to the ones you used, including the chroma blur.

So, my question is, can I fix this by persevering with the lighting, or does it look like I need a better camera?

The attached still is fairly typical of what I am seeing ...

Thanks for any advice you can spare!


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Re: Chromakey : Green Halo

Post  SonicOrbStudios on Sun Oct 05, 2008 6:04 pm

I get the same problem every now and then but mostly around my black shirts keying out or getting green. I use halogen for the screen lights and incandescent for the subject lights. I do use a cheap camera, (Sony DCR-HC32 Handycam) but have access to some Canon XL1As and Sony HDR-FX1s so some time next week I will set the school's green screens up and light them with their good lights. I will then film with my Sony Handycam and the schools Cannon. Then I will bring both cams back home and try them on my lights and screen to see how they compare.

These results will show how both the lights and cameras effect everything.


Edit:
Yea I also have to get some good lights so I quit mixing...
TubeTape has that nice "TTL MXLIGHT TWIN LAMP THREE SOFTBOX KIT WITH BOOM" for around $600 which I may get. I really like boom stand so I can do the back light centered.
I believe those are halogens so I can still use my work lights to light my green screen without any problem.


Last edited by SonicOrbStudios on Tue Oct 07, 2008 6:01 pm; edited 3 times in total

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Re: Chromakey : Green Halo

Post  aimc on Sun Oct 05, 2008 6:46 pm

Thanks for the reply - I'll be very interested to hear if the camera does make a difference.

I have spent a few more hours working on this and have found that I can get a reasonable effect if I white balance for Halogen and keep the background lit with daylight fluorescent - I then get a purple halo but I can tune that out with the color corrector, so I guess I am mostly there now!

When I get some more cash I'll splash out on softboxes all round - should help a little. It does seem that you can get resonable results even with cheap cameras as long as everything else is spot on.

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Re: Chromakey : Green Halo

Post  tishon24 on Sun Oct 05, 2008 10:17 pm

Well if you have a soft box you wont have that problem well i think if i am not correct me please correct me or the guru mark Apsolon can help us.

Mark Help us Smile


Last edited by tishon24 on Sun Oct 05, 2008 10:17 pm; edited 1 time in total (Reason for editing : made a mistake)

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Re: Chromakey : Green Halo

Post  Mark Apsolon on Sun Oct 05, 2008 11:43 pm

try lighting yourself a little more than you background. That normally takes care of most of the spill

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Re: Chromakey : Green Halo

Post  aimc on Mon Oct 06, 2008 8:39 am

Thanks for the tip! I'll let you know how it turns out.

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Re: Chromakey : Green Halo

Post  SonicOrbStudios on Thu Oct 09, 2008 10:17 pm

Sorry guys but the green screen tests will have to wait a few more days. I went to the editing lab a few times yesterday and today and could not find the lab assistant. He is the hardest guy to find in the building LOL
but I need him to unlock the gear and get the paperwork for the camera and such...

I have a few tests soon and so I want to focus on school for a few more days. After that I'll get back to the video stuff.

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Re: Chromakey : Green Halo

Post  tishon24 on Sat Oct 11, 2008 8:48 pm

oh thanks mark apsolon any way i also made a new web its same as mark apsolon just thought i should it is http://tishon24.forumotion.net/

Register on my website and have fun

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Re: Chromakey : Green Halo

Post  SonicOrbStudios on Mon Oct 13, 2008 5:29 pm

Ok update guys, it's been a little crazy the past few days...
I don't think I'm going to be able to set up a green screen at the school. The lab assistant is very lazy and mostly hangs out on the computer doing nothing. Rolling Eyes
I asked him today if he had time to setup the screen and some lights and he didn't. That is actually the 3rd time I asked him...

So what I'm going to do is simply check out one of the cameras (Canon XL1 series) in a few days and compare that to my Sony camera in my studio with my mixed lights...

I would have been nice to be able to get the nice pro kit setup at the school but I just don't see that happening.
So yea sorry about all that, I will have some video footage posted in a few days.

Edit, got one of the cams from the college today, have a few things to film the next few weeks.
Anyways they had a Sony HDR-FX1 so I got one of those and will be filming some green screen shots today. It may take a few days to edit up and get on youtube as I have a lot of work to do now with this huge 5 week project I was just given.


tishon24 wrote:oh thanks mark apsolon any way i also made a new web its same as mark apsolon just thought i should it is http://tishon24.forumotion.net/

Register on my website and have fun

Not bashing you tishon24 but I really feel you are not ready for a website of your own at this time. It seems like you still have a lot to learn about video production.
Keep at it though, before you know it you will be a pro.

Also I'm not sure if Mark allows advertising and IMO posting your site URL like that is considered an advertisement.


Last edited by SonicOrbStudios on Sat Oct 18, 2008 8:29 pm; edited 1 time in total

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Video

Post  SonicOrbStudios on Fri Oct 17, 2008 3:50 am

Here's that comparison video guys:

http://www.youtube.com/watch?v=S5J42bqP-kY

I used my Sony HC32 and the schools' Sony HDR-FX1 in my studio using my lights.

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greenscreen halo

Post  bilco82 on Wed Sep 23, 2009 1:44 am

Hey guys,

I am new at using chromakey and I am getting a green shadow that shows on some of my edges. I have 6 500 watt lights, 2 on my screen and it is lit evenly, 2 on the back of my subject and 2 on the front of my subject. Does anybody see a problem with this lighting set up, if not what else could be causing this green halo?
Thanks!

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Re: Chromakey : Green Halo

Post  SonicOrbStudios on Wed Sep 23, 2009 8:58 pm

- How far away are you standing from the screen?
A few feet will not cut it. Get 6 -7 feet, (or more) away from the screen to prevent that green from reflecting back onto you. Standing far from the screen also allows you to focus your camera on the subject and blur the background a little which helps even more.

- What software are you using to key out the video?
Some software works better than others. I found Adobe Premiere to do a cruddy job most of the time however Adobe After Effects does amazing since you have more keying plugins and settings.

- Is your camera any good?
A good camera makes quite a bit of difference as seen in this video.

- As suggested before, try lighting the subject more than the screen but don't over-light or you will over expose the scene.

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Re: Chromakey : Green Halo

Post  bilco82 on Wed Sep 23, 2009 9:39 pm

I do have my subject standing 6-8 feet from the wall, I am using Sonyu Vegas Pro 9. My cameras are Sony DVD403 which are not professional but I get very good video quality and they record in 16:9.

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Re: Chromakey : Green Halo

Post  SonicOrbStudios on Fri Sep 25, 2009 9:24 am

I suggest giving After Effects a try. Get the trial from the Adobe website and see how that does. I do all special FX in that program just for the good flex it has.

It also may be that you are new to keying and so it will take some practice before you know how to set things up just right to get all that green gone.

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Re: Chromakey : Green Halo

Post  bilco82 on Fri Sep 25, 2009 9:53 am

Thanks for you help Dave! I do have Adobe After Effect but I haven't used it. Can you suggest some good tutorials on the web anywhere.

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Re: Chromakey : Green Halo

Post  SonicOrbStudios on Fri Sep 25, 2009 12:50 pm

You can find a few on my youtube page. I'll find some time this weekend to do a Your Questions Answered episiode on Chroma Keying in AE.

youtube.com/sonicorbstudios

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Re: Chromakey : Green Halo

Post  SonicOrbStudios on Mon Sep 28, 2009 11:16 am

Heres that video I mentioned I would do

Your Questions Answered 6 - Keying In AE

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Re: Chromakey : Green Halo

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