Better EX3 settings for Greenscreen ?
by Joe Tyler
on
Oct 12, 2009 at 11:53:46 pm
I've been shooting greenscreen for years, more recently with the EX3. Just last week I had a client have some problems keying with the EX3. We appeared to have a bunch of noise in the green.
First, I'm not talking lighting, I think everyone knows how important lighting is to a green screen. The subject was well lit (67 IRE in the flesh) and well edged with a touch of Minus G on the backlights.
Green screen was solid and even (30IRE across the board).
My setting were HQ - 1080/30P. Gamma curve Standard 2, Color curve was Cine1 (based on previous shoots of the same project). Camera Gain set to -3dB, shooting between F5.6 & F4 with Nikon Lenses (24,50,85mm) and a letus elite adapter (fresh batteries). Any red flags?
Anyone have a favorite setup? Gamma curves? Color settings?
Just looking to improve the EX3 experience for the clients & community. -Joe
Re: Better EX3 settings for Greenscreen ? by George Griswold on Oct 13, 2009 at 2:31:36 am
Joe-
It seems to me that a few things could be causing problems..
1. Green screen likes to be at 50 units... 30 may be low enough to show noise-- especially of gamma curves are pulling that value up from even lower number.
2. I would lose the DOF adapter-- does not perform its function in this setting and may also be inducing noise in what should be an even field of green. (The GG was on right? -- who hasn't done that once)
3. Cine 1 ... I would stick with the standards for Green screen.
Re: Better EX3 settings for Greenscreen ? by Greg Ondera on Oct 13, 2009 at 3:51:03 am
I was just talking to a cameraman friend of mine who does greenscreen quite often, and since you have a 4:0:0 compression scheme going to the SxS cards, it makes sense that it is better to take the signal from the HD/SDI output which is a 4:2:2 scheme and record onto something like the Convergent Design nanoFlash <http://www.convergent-design.com/CD_Products_nanoFlash.htm>. However the nanoFlash does not record audio, so you'd use the SxS cards for that and synch them up.
Re: Better EX3 settings for Greenscreen ? by Craig Seeman on Oct 13, 2009 at 1:47:13 pm
4:2:2 is certainly better but XDCAM (which is 4:2:0) can pull GREAT keys when shooting progressive because of the high resolution (pixels very close to each other). I've done great "1 click" keys using Final Cut Pro's built in keyer shooting 1080p30.
The OP's 30IRE for green screen is WAY TOO LOW IMHO. You want clean, well saturated, noiseless green. BTW this is why looking at a RGB Parade can help so you can see the green channel specifically.
Re: Better EX3 settings for Greenscreen ? by George Griswold on Oct 13, 2009 at 2:50:03 pm
Another observation... The use of minus green on the backlight is not recommended because of the hue that it puts on the edges of the subject. Using minus green with a blonde is a real mess. If you have the subject away from the green screen and have a nice rim light that works just fine with modern NLE keyers. The minus green trick is only necessary if you are crammed up against the backdrop... like in that hotel room the client got and told you it was "plenty big enough".
Re: Better EX3 settings for Greenscreen ? by Dean Sensui on Oct 13, 2009 at 11:01:24 pm
I'll add my vote to 50 IRE on the green screen. And there's no need for a backlight unless the scene in the background plate requires a source to get the foreground subject to match.
Turn off any sharpening to get clean edges.
I'm using Primatte in After Effects and can get flawless keys. I've keyed hair, veils and transparent plastic product wrapping (the type that requires a 2,000-watt laser, bandsaw and a gorilla to open).
Re: Better EX3 settings for Greenscreen ? by Rafael Amador on Oct 14, 2009 at 1:26:22 am
I don't think the Letus will be of any help in this scene.
30 IRE for the background I think is too low.
Also I don't understand recording by default at -3db.
Cine Gammas for a green screen I believe is a risk.
[Greg Ondera]" However the nanoFlash does not record audio, so you'd use the SxS cards for that and synch them up. " The NANO records an amazing 24 bits audio.
The EX-1 footage keys great without need of recording from the SDI.
rafael
Re: Better EX3 settings for Greenscreen ? by Bob Pierce on Oct 15, 2009 at 2:57:37 pm
As has been stated elsewhere on the Cow, it's a good idea to ask your client what they plan to use for the keying, and determine the optimal exposure recommended for that product. Keylight, the keying plugin included with After Effects for example, recommends 74 ire. I think there used to be the belief, (shared by me) that a darker, more saturated green was desirable. Not true - 30 ire is way too low. You can pull a nice key with XDCAM, but you've got to be extra vigilant with the lighting and exposure.
Bob
www.lightstreamassociates.com
Mac Pro 2.66 - 8GB memory -
Mac Book Pro 2.33 Duo -
FC Studio 2 - Kona Lhe
Adobe Production Suite CS4 -
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Re: Better EX3 settings for Greenscreen ? by Joe Tyler on Oct 15, 2009 at 11:50:35 pm
My bad, typo. Green Screen was actually 40 IRE across the board not 30. typically my client uses the quantel editing system, they can key just about anything. I'm just trying to make everything easier.
Thanks for all of the feedback, I'm just interested in Gamma curves specifically for greenscreen. if anyone has a favorite gamma curve/setting that they would like to share.
joe
www.killianthered.com
DP in the Washington DC Area
EX3 Owner
Re: Better EX3 settings for Greenscreen ? by Pat McGowan on Oct 16, 2009 at 11:02:03 pm
We just did some GS work yesterday and brought one of our MACPRO towers with KONA LHe on set. We used the HDSDI tap from the EX-3 camera and bypassed the SxS cards. There seems to be a definite improvement in the keys. We also rolled to the SxS card and plan on doing an A/B after we get through the project. Will report back.
