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lite ring/chroma matte problems

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bumpthekoala
lite ring/chroma matte problems
on Jul 6, 2007 at 5:29:34 pm

We use a Lite Ring/ Chroma matte set up. Maybe its my skill level but I cannot get this key to be perfect. I'm told that Lite Ring keys are suppose to be fantastic but I always get a shadow and a dark halo. When I try and key in Composer and AE it looks horrible. We duplicated the lite ring example set up of a 500 watt key, a rifalite 700 watt fill (we also used a 500 watt fill) with soft box and two backlights for seperation. I can fix it using ultimatte going right from the switcher but cannot get a clean key in post. The shadow is coming specifically from the Lite Ring.

This is the key I get: http://good-times.webshots.com/photo/2568176970098745421cOgslL?vhost=good-t...

Anyone else have an issue like this? Anyone have some advice for how to clean up this kind of image in post?


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N.Adam.Smith
Re: lite ring/chroma matte problems
on Jul 6, 2007 at 9:27:55 pm

We get the same shadow, I'm not sure how you'd NOT get the shadow, since the LED ring is a light source.

I've yet to find a good solution... bring the subject closer and you have a softer but larger shadow, and you risk tinting them green. Move them back close to the screen and you have a harsher shadow but you can crank the LEDs up and try to get the screen to pop more.

I'm no expert at keys, and using this system I've had about 10% easy keys and the rest some combination of troublesome and/or extremely vexing.

I wasn't there at NAB when the boss and co-workers selected this system, but I'm the primary user and honestly I would have preferred to spend this $4,500 elsewhere.


--
Video Photographer / Avid Editor
Maximus Media Inc.


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Bob Cole
Re: lite ring/chroma matte problems
on Jul 10, 2007 at 1:23:45 am

I'm not familiar with the system, except for quickly walking by it at NAB -- GREAT magician, scary price tag on the gear.

Is there an actual green background, or does this system somehow create one? How close to the background is your subject? Looks too close.

Have you tried duplicating their instructions exactly (you say you added a light, which may have changed something)?

Can you return it?


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N.Adam.Smith
Re: lite ring/chroma matte problems
on Jul 18, 2007 at 5:18:19 pm

The system uses a dark grey fabric with embedded glass micro-beads... it has a very directional reflective property, much like safety tape or a freeway sign. The green (or blue) LED ring mounts on the camera lens and lights the background. To anyone a few degrees off-center the background still appears grey, but from the camera perspective the background is bright green.

Quick to set up, no fancy lighting required for the background so you can use less lights and it's actually better to have the subject up close to the background so you can shoot in tighter quarters. You can pretty much go nuts with lighting and not worry about the background, the only caveat is you cannot place any lights near the camera lens, as they'd reflect off the background just like the LEDs do.

Issues? Well the green LEDs are a light source that's attached to the lens, so...

Areas of shadow on the front of the subject may be lit/tinted by LEDs

Reflective subject matter is bad news

Not usable with teleprompter

Lateral movement is fine, but camera moves towards/away from the background will increase/decrease the background intensity and may tint your subject unless you try to 'ride' the LED output (fun!)

And finally the issue we've been discussing, shadow/halo caused by the LED ring.

So it's got some benefits, and I'm sure with some testing and research I could wind up getting things done better/faster in post, IMO this $4500 could have been wisely spent elsewhere.

--
Video Photographer / Avid Editor
Maximus Media Inc.


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Dennis Size
Re: lite ring/chroma matte problems
on Jul 10, 2007 at 1:59:13 am

It will never be perfect. I tried it a few years ago and abandoned the idea of using it .......for the obvious reason.

DS


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