Green/Blue Keying - Tungsten/Daylight Lighting

Segarza

Segarza

Well-known member
Hi guys!

I've started doing some tests for an upcoming project that requires extensive chroma keying. So far I've shot 720/24PN and 1080/24PA against a green screen using daylight balanced lighting setup.

I tried both AE's Keylight 1.2 and Primatte 4.0. I've gotten much better results, most importantly repeatable results, with Keylight.

My first attempt was a nightmare, I shot a female (walking and talking) with no backlight against a green screen (720/24PN, daylight balanced lighting). Everything BUT the hair keyed out perfectly. Tried layering several keys, really tight garbage matte, blurring the chroma channels, etc etc. And just couldn't make the jittery noise around the hair go away.

The second attempt went much better. I shot 1080/24PA WITH backlight (daylight balanced). I managed to pull a pretty decent key of the same subject. When composited against a solid color "acceptable" levels of noise around the hair would be noticeable. But when composited against video footage, the noise was barely noticeable.

I've still more testing to do. Can anyone out there share their experience?

Please correct me if I'm wrong, but a green screen should allow for a cleaner key?
Are the HVX CCD's natively tungsten balanced or daylight? Would changing my lighting setup to a tungsten balanced setup make any difference?

Thank you!
 
How far was your actress from the green screen? It's really important to have good separation so there is no spillage from the lighting...
 
I used a 6' x 7' collapsible screen... just received a 10' x 24' reversible green/blue screen and more lighting equip... that will allow a greater subject-green separation. Are you aware if tungsten or daylight balanced lighting makes a difference with the HVX?

I recall the DVX generating a much cleaner image under tungsten lighting. I actually carry a 85B filter with my DVX. Haven't had the time to test with the HVX.
 
Yeah, the size of the screen determines how far you can get away from it. You were probably at the limit...
 
Yeah, the size of the screen determines how far you can get away from it.
Click to expand...

i dont quite see how the size of the screen matters. you should generally apply a matte to your source footage anyway. and if you do that. you could be as close or far as you want...

a general rule of thumb for me is a MINIMUM or 8 feet from screen to subject. and another 8 feet from subject to camera.

ive found no noticeable diff between daylight and tungsten as long as youre not mixing the two - i.e. using one for lighting the screen and the other for lighting the talent.

tell us more about your light setup. sounds to me like youre having spill issues.
 
wgzn said:
i dont quite see how the size of the screen matters. you should generally apply a matte to your source footage anyway. and if you do that. you could be as close or far as you want...
Click to expand...

That depends on how much of your subject you want in the frame. If it's a head/shoulders shot, then it might not matter as much. If it's an entire person or persons, then you'll have problems.
 
wgzn said:
i dont quite see how the size of the screen matters.
Click to expand...
Well, what I was thinking is if the screen is too small, the further your subject is from the screen, the greater the chance that you won't be able to get a key all the way around the subject because the subject will be proportionally greater the further the camera and subject are from the green screen.


EDIT: David beat me to it.
 
I used three lights on my last (and most successful) test:
- Lowel Omni 650W with Full CTB as a Backlight, 1 foot above and behind the screen
- Kino Diva Lite 400 to light the screen, positioned behind and out of frame to the right of the subject. Used a 216 gel on nearly half of the fixture to balance the amount of light falling on the near and far sides of the screen.
- Kino Diva Lite 400 with Flosier Diffuser to light the subject, about 20 degrees camera left.
- Also used a photoflex frame kit with white screen to bounce some of the backlight back to the subject from underneath the camera.

I was very limited with the amount of lighting equip.
 
a.light your talent apart from the green/blue screen (no spill on the screen from talent lighting) light for matching background lighting(video/graphic) insert
b.evenly light your screen eliminate (best you can) hot spots on the screen... use a light meter.
c. focus, focus, FOCUS.... find the HVX viewfinder setting for color or bw... put it on B&W... do not use an external monitor or the foldout for setting focus. PERIOD
d. Talent 5-8 feet from key screen -- ALL framing.... understand your non-linear editing garbage matte plug in (works wonders)
e. if you have the capability, run a few tests (compositing test) before you commit to a lighting set, have a couple of 250's or 500's on stands to kick and/or fill talent cool spots (edges)

p.s. the HVX200 provides (when lit well) great 4:2:2 footage for green screens
 
Thank you!

What troubles me somewhat, is most probably having to use kicker and/or backlight to get a decent key. My background plates don't require backlighting.

Everything keys exceptionally well except for hair, specially darker areas on the hair that aren't hit by light.

Should I light my green the same as my key? Under? Over?

Thank you!
 
Hi again!

Achieved some amazing results using DvMatte Pro 3. Shot at 1080 24PA (Cinelike_V/Norm), dialed down detail settings. Increased the screen to subject distance, that definitely helped. It allowed me to eliminate the backlight.

I ended up pushing two 1000W ArriLites through 216 Diffusion for the screen (10'x24'). Flagged the lights so they wouldn't spill onto the subject. Two Diva-Lite 400's with flossiers where used for the subject/floor. And ended up bouncing two Arri 650 Fresnels to fill the floor in front of the subject.
 
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