C100: Green Screen C100 + Ninja2

S

Saddler

Well-known member
Hi, I have a C100 with Ninja 2 on order, primarily to be used for green screen shoots and some interviews. I've been doing research but was wondering if anyone could give advice on ideal workflows. Mainly until I have the camera in-hand I'd like to know how others have found working with c100 footage for keying in regards to 422 vs. HQ, and is c-log the best profile for keying or are do the other profiles work okay too?

Green screen will be lit with 2 4Banks with daylight bulbs, talent with a spiderlite w/ daylight bulbs, a diva 401 w/ either daylights or a mix, and an Arri 300. Delivery is web, most likely 720/30p. I haven't done heavy keying much since a few years back when I did it with Shake, so I'll be working out the workflow for keying between Ae and Pr. My other video guy I work with doesn't do Ae, so I'm hoping that I can setup an easy workflow in Pr using an adjustment layer for an Ultrakey, a Lumetri LUT if shooting c-log, and finer color corrections.
 
I can't speak to the C100 and Ninja combo, have done a lot of green screen shoots with the C300 though. Here's my two cents.

- Don't shoot log. I use a Cine 1 or Cine 2 gamma with Log Color Matrix, with saturation bumped up a few points.

- Lower ISO's are better. Non Log base sensitivity is 640. I try to go as low as possible to combat noise. Be sure to black balance after the camera's up to operating temperature.

- Faster shutter speed. If there's a lot of movement in the peice bump up the shutter for a crispier image. I'm a fan of 144'degrees

- Don't shoot wide open, if you've got the light to shoot at 640 ISO and a 5.6 go for it.

- Get the greenscreen bright. From my experience with post professional they'd love to have the green screen up around 60 or 70 IRE on the wave form. And of course as evenly lit as possible.

- If you get your screen up to that exposure you'll likly have green splash on your talent. Back Light with Magenta (minus green gel) to combat that. That will help with subtle green reflections on skin and hair. Can also do 1/2 magenta depending on the strength of the GS lighting.

- And yes avoiding internal compression is recommended.
 
Jim, great set of tips!
One more: keep talent as far from screen as possible to avoid bounce. You'll get two benefits: less green bounce onto talent, and seeing less detail/imperfections of the green screen.
 
On the C100, CP8/WDR works well for us in a talking head scenario. We use a Lastolite collapsible 1m x 2m green screen, lit with three 4 x 2ft kinos (although you could get away with two, left and right.) Talent has a Diva 401 keylight plus a Dedo for rim light. All Kino tubes are tungsten balanced, to play better with the Dedo.

We're actually using the native AVCHD codec for this and have had absolutely no issues at all keying in After Effects.

Ben.
 
Thanks for all of the replies, especially Jim for your very detailed list. Jim, I have a couple of questions:
1. Have you tried shooting green screen with the WDR gamma? I think I've read that it has been added to the C300 one of the recent firmwares (though not C500 yet), and apparently Canon has dialed in the color science of this profile spot on in the latest revision.
2. How long does it take for the C cameras to get up to operating temp?
3. I was planning on shooting at 5.6 and a faster shutter than 180 but I wasn't sure about how much faster, so thanks for the recommendation of 144. But I was planning on the standard gs exposure of 50-60 IRE. Is your recommendation of 60-70 IRE specific to the C cameras? In my current studio space I don't know if I'll be abler to get the talent much further than 8' from the screen. I also was planning on using my ARRI 300 for the backlight though I didn't add a minus green to my order. Will the 3200k be able to help fight the green spill without a minus green (with the rest of the set lights all being daylight)?
 
Ha, name's actually John. just use my initials for forums.

-I haven't tried WDR for green screen since it's relatively new to the C300, but the stuff I have shot with it has had great color tones.

-Heating up, shouldn't take too long. I'll usually turn the camera on, light to monitor and then try to do a black balance before the first shot. Especially for green screens. I'm less dillegent on non-vfx shoot in terms of black balancing.

- I had always lit GS at close to 50IRE. It wasn't until I started working with a guy at Stargate Studios (http://www.stargatestudios.net/Virtual-Backlot) , that I learned the high end guys really like it to be much higher, when possible. Just makes their job a lot easier.

- That color differential may help you enough with the back light. The magenta filtration really comes in handy when your GS wraps talent and you've got green spill all over the place. If it's just a single wall and you're straight on you should be fine.
 
Thanks, Jim (j/k).

Well dang, I'm not going to argue with Stargate Studios ... that's some serious work they're doing!
 
How do you fine set the shutter when set to angle? When I am in angle mode it doesn't allow small increments ... it jumps in 30 degree increments.
 
Just one more tip: TURN SHARPNESS OFF. -10. Otherwise you get a tell-tale black line around edges, and the only way to get rid of it is to nibble the key in a little, and that takes away the glorious detail from the picture.

I'm using the Ninja Blade habitually in my chromakey shoots now - the joy of being able to replay shots back with sound, skip around within a take and so on, and the AVCHD is just a backup recording. In the past, I've done keys I'm proud of using just AVCHD - no problems at all, but they were fairly straightforward keys using a hybrid keyer rather than pure chromakey. As things get tougher, there's just a little more wriggle room in the ProRes stuff.
 
Thanks, yeah I'm shooting at -10 sharpness. So can someone tell me how to go about dialing the shutter angle down in small increments--I want to set it to 144.

I'm shooting for using Wide DR gamma, either Wide DR or EOS Standard Color Matrix, 640 ISO and f/5.6. But with the lowered shutter and shooting at 30 fps, I'm not sure if I'll have enough light. Is it better to bump the ISO up a couple of notches, or lower the f-stop a couple of notches?
 
Noise is your enemy with greenscreen. It creates a 'boil' that will hamper your tighter keys and push you towards a more generic setting. Having said that, I haven't tried (meaning I should try) doing a de-noise yet. It could be horrible, but then again it may be the lesser of two evils.

I'd prefer to open up a little (but no further than f4). Here's a challenging thought - have you considered C-Log? That sort of 'assumes' ISO850, but shoots to protect highlights by making the overall image a little darker so it's like underexposing 850 which brings us to 640. That's a little unfair, but hey - it's a free stop.

As far as your shutter angle is concerned, 144 only exists in 24P and PF24 modes. BTW, have you tried using the ClearScan mode? No, it's not in 'angles' but you can eyeball it (with a good separate monitor) to get rid of LED flicker, computer screen issues and CRT scan problems.

I'd really stay far away from the EOS Standard Colour Matrix - way too saturated for 8 bit and chromakey.

With due respect to others, I tend to light my chromakey to IRE50 - some recommend going a little brighter than that - 60-65. That may be fine if you have enough distance, but a hotter background will cause more spill, and spill is bad. But the point is, ideally, you're setting your exposure to the chromakey background, then varying the intensity of lamps on your subject with distance, diff, scrims and even dimmers to get your overall exposure. Do you need more light?
 
Thanks for the input. I'm trying to optimize my set so that I don't have any noise to deal with while still shooting ProRes (w/o in-camera NR). If I have to compromise and push up the ISO, then I guess I'll have to bite the bullet and integrate a denoiser plugin pre-key.

I had originally planned on going C-Log, but after reading some other threads here it seems that lots of people recommend avoiding log workflow for green screen.

That's a shame that I can't micro-adjust shutter angle in 30p--I haven't yet tried the ClearScan mode, but will now to try and approximate 144 degrees or thereabouts. My main purpose in wanting to adjust to a lower angle than 180 is to reduce having to deal with the green getting muddled with the motion blur of the subject.

Ok, thanks, I'll stick with Wide DR color matrix.

I've been testing with my screen at 65 IRE. I haven't noticed significant green spill on the subject which is 8' from screen, though there is slight bit. However, I think I may dial the IRE down so that there is a wider range to work with in separating the exposure of the subject from the screen.

So I'd shoot 24p, but I need to mix with video game footage which is why I want to shoot at 30p. I'm still a little uncertain how to deal with the workflow for shooting 30pn, wrapping to 60i out to the Ninja 2, and then properly importing that so that it reads as a solid 30p in Premiere. In my tests, with the Ninja set to 60i, both 30pn and 60i settings in-camera seem to interpret fine as progressive footage w/o pulldown issues when brought into Premiere and set in a 1080/29.97p sequence. Is there something I'm overlooking in my workflow?

Thanks.
 
Well I finally got things dialed in real well. I'm shooting Wide DNR gamma and color matrix, sharpness -10, NR +2, master pedestal -2, ISO 640, shutter set to speed 1/90, green exposed to 50-60 IRE. For some reason with the same lighting and settings, I had to shoot f/4.0 yesterday, but it was back at f/5.0 today. The only thing that changed in the environment is that I had the AC set cooler to keep the actors more comfortable.

I'm not getting really nice keys even with stress testing having an actress twirl her long hair around. Ultrakey didn't work well so I switched to Keylight which worked like a charm.
 
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