Shooting Green Screen with RED by candle-light and LEDs.

[Paul Kalbach]

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I recently bought a CKL-100 system from Datavideo. It's a new competing product similar to the ChromaFlex / LiteRing system from Relecmedia that uses green or blue LEDs circling the lens to illuminate a highly reflective fabric that's imbedded with millions of glass breads. The cool thing about the Datavideo system is that its' LED ring has both green and blue LEDs, so you can change colors at the flip of a switch. This also makes it more cost effective than having to buy 2 separate rings for the Reflecmedia system. Looking at the screen off-axis, it just looks like grey fabric. Here's the set with work lights on:
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Looking through the lens on axis, it appears as a bright green or blue. This particular screen had a manufacturing defect manifesting as dark bands of uneven reflectance, but Datavideo has replaced the screen.
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Since the background doesn't have to be lit at all (in fact it's best to keep light off of it; only the LEDs circling the lens light it), my first thought was to see if I could pull a green-screen matte from RED by lighting the foreground with candle-light only. I felt that it would be very difficult to pull off such a shot with traditional green-screen lighting, as the ambient light spilling over from the amount of lights required to light the screen evenly would overwhelm any candle-lit feel of the set. Using only the LED ring to light the background allowed the studio to be totally dark except for the lighting on the foreground; in this case candles, as seen by my Nikon:
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Actually, I did use a scrimmed-down 200 watt Mini-Mole backlight rimming my wife's shoulder to motivate the patio light in the background plate. Ideally, I should have had another Mini-Mole on a flicker generator where the fireplace would be to motivate the firelight, but I don't have a flicker generator. But, whatever, it's just a test. I shot this on Build 15 at ISO 500. The foreground was shot with a 50mm Zeiss Planar (Standard Arri Mount with PL adaptor). The background plate was shot with a 16mm Zeiss Distagon (as I couldn't get back far enough to use the 50mm) and threw the focus soft to simulate a shallow DOF. I tried to use the lite ring on my RED 18-50mm zoom, but due to its' size, it would only mount when the lens was zoomed full in to 50mm; preventing it from retracting into the lens barrel for wider focal lengths. It works well with my primes though. It comes with a couple of adapters to allow using on different size lenses.

The final composite:
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Initially, I tried to pull the matte in Shake using Primatte, but being unfamiliar with it, had some problems with the highlights in the candles blowing out. I wound up pulling a quick and dirty one using a plugin called DV Matte Blast in Motion. I can't wait to try this type of shot with build 16.

 

[Gunleik Groven]

You should try keylight instead of primatte...

Nice test, though. Keep it up!

 

[Alexander Nikishin]

Very interesting, I'm guessing this screen works like a high power retro-reflective projector screen, great test.

 

[Jeff Coatney]

Great idea.

 

[MiguelOrtega]

id love to see more results from this.. so would u recommend this over the reflectmedia?? obviously the price difference is huge but what are your final thoughts on it. once they replaced the screen was it satisfactory?

 

[Paul Kalbach]

id love to see more results from this.. so would u recommend this over the reflectmedia?? obviously the price difference is huge but what are your final thoughts on it. once they replaced the screen was it satisfactory?

I would recommend it over Reflecmedia for economy and the convenience of the dual-color LCD ring. The replacement screen they sent was satisfactory in that it was more consistent and even in its reflectivity. The first one they sent had horizontal bands about one foot wide along the top and bottom edges that didn't reflect as well as the rest of the screen. Perhaps the best system if you can afford it would be the DataVideo Dual LED Ring combined with the Reflecmedia screen. I have a sample of a few square inches of the Reflecmedia fabric and it is obviously a more efficient reflector, and probably more robust as well. The DataVideo screen is not going to
do well for full-body shots (don't walk on it!), but is an economical portable solution for smaller shots. For full body shots with this screen, you could use traditional fabric or the Pro Matte Flooring from Pro Cyc and light from above (or BaseMatte from Reflecmedia if you have the bucks).

I just discovered an alternate source for reflective fabric: http://www.magicmatte.com/
I just requested a free sample and will compare....

 

[amrrahmy]

i remember seeing a low light test(candles) of the arri-d21 on there site, no green screen, no noise, no weird digital red coloration, and it was perfect. it really shows diffs between the cameras, but u kind of screwed it up by placing the candles too close, and no lit background, u can use the candles to light the seen, instead of making a scary movie in the studio.
also changing the angle slightly, would make a better lit and less contrasted seen, and would make a something close to the end result u were trying to do.
but at least u got a scary setup ready, when u want to make a horror scene.

 

[conrad gaunt]

Interesting method.
I have software for green screening without a screen at all (as long as the camera is static), but have never added a user friendly interface (as it was for personal use, and written about eight years ago). I shall test and optimize it for use with my R1 when I get chance, and will add an interface if it works well. I wrote it at the time so I could have colour actors in a b&w world (or vice versa), but whilst filming in situ.
More interesting is someone I`ve met at a university near me who has a much more robust software that does the same thing, but he believes he`ll be able to remove foreground objects from background objects even with moving camera shots in the future. I intend to offer him some high-res R1 footage to help out when I get time. His software looked very polished already when I saw it, and may be a glimpse of the future of compositing I think.

 

[amrrahmy]

and u need as much of the camera data as possible, so don't go for keying, choose a nice background that would work without keying.

all the images are not in focus for some reason, if the image is not 100% in focus, it magnifies whatever noise the camera would store adding it to the out of focus image, not pretty.

same thing with highlights, it discards most of the data, making it unusable. and finally dont light directly to the object being filmed, that's not right, even if u cant see that by using small amounts of light, it's always wrong(always), if it's not intended as an effect(maybe to blind the audience from the foreground, that'll go well with the other scary seen and make a masterpiece.(well maybe not a masterpiece artistically but it will sell very good for some reason - people like scary horror and thriller movies))

 

[michael zaletel]

I bought the CKL-100 system from Datavideo, tested it and quickly sent it back. Some of the problems are with the Datavideo in particular and some are simply with the underlying concept. The biggest problem I have with the technology is the halo-shadow created against the background and the reflections in the eyes of the talent of the lite ring. I had hoped this would be an acceptable substitute for a traditional green screen but honestly, I don't think it is even remotely close. Remember the Datavideo system is primarily targeted to schools for standard resolution green screen news presentations. I just don't think the technology holds up at 4k or even 2k.

-shooter

 

[amrrahmy]

can u try:
less iso(a little bit (go native))
and tweaking aperture and shutter to match
no light directed to the actors, and spacing the candles from the actors(a bit) and spacing the camera from the candles(a lot).
witha bit of sense and tweaking that should make better results without changing or adding to the budget, just a bit of fine-tuning and everything would run smooth and u'll have all the needed data to play with in post.

 

[amrrahmy]

or changing the lens to a more suited one for the scene.

 

[Vigen Vartanov]

I will try to , we have same system ring . Nice idea.