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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Green Or Blue Screen

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Ramis

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Hi everyone,

I've got a Music video coming up ,wich is going to be shot on Red , I had a unpleasant experience in the past shooting 2K (100fps) ,tungsten with blue screen , Therefore I'm definitely going for the HMI option, I've read that the new 16firmware has solved out , not entirely though ,the shadow's noise.
Since I'm going to shoot again in 2K (100fps) and chroma, by the way what's the best choice green or blue, any thoughts, opinions or tips will be extremely welcome.

P.S: We'll be shooting with rain effect, not in the wide shots , (3 D will be used for that purpose), but in close-ups, as far as I know, you're better off using a black background and a back light as usual, but ha ha!! Blacks and Red one .... it does not sound as a good idea to me .


Thanks to you all.
 
just shot a spot for NIKE....used RED build 16 rated @ 320.... shot with a 6m x 8m bluescreen. I had 8x 5k's rigged on truss up top and since I wasn't worried about stop I skinned each with 1/4CTB. I had 2 more 5k's on the floor same config.....the subjects key light was 2x 20k's and 2x 10k's (one of each on each side in almost a semi circle) and very very soft for complete wrap around. the keys were clean as far as color....................there were no keying issues as far as I know and I would have heard of something by now....the spot will have a truckload of animation and effects.....oh, one more thing.....I had the subject stand in the center of a 5m diameter turntable, which obviously turned to some degree.
hope this helps...
Eric
PS....I woulda posted some pictures of the shoot, but sorry, I am not allowed. I will post a link when the spot is completed, which will be in 4 weeks or so.
 
GREEN.

Green is the way to go for most subjects, whether you're shooting RED, film or HD. With RED and other bayer-sensor cameras, Greenscreen will give you more edge detail for keying if you light right and don't produce edge halos or shadows. Blue has its uses and sometimes you can't get away from using a blue screen. RED handles bluescreen quite well if you light it right -- 5600~6000K HMI or Fluorescents or outdoor (use the great HMI in the sky).

Where I see most bluescreen go bad with RED (and other digital camera systems, because most struggle with red or blue channels in relation to green), is people don't throw enough light on their set. You have to be careful of spill, but move the talent / subject furrther away from the screen, know when to shoot blue, etc.. Look at spitfire44's post above mine. That's a lot of photons he dumped out there, but reads like it worked just fine.
 
These answers are really helpful, thanks to you all mates !

but , Should I have trouble by shooting
real rain (backlighted) and a dark blackground? Blacks and Red did not go together at all with previous firmwares...., and crushing blacks means losing rain drops...
 
100% green hmi.
The results are excellent.
 
Jeff Kilgroe said:
GREEN.

Green is the way to go for most subjects, whether you're shooting RED, film or HD.
Click to expand...

Hi Jeff,

With film I strongly disagree with that as a blanket statement. I have been advised to shoot green many occasions, however when I shoot against both green & blue, the blue usually produces a better result. IMHO the overall color of the final composit should be taken into account.

Stephen
 
aside from the obvious decisions based on the subject you will be shooting(are they wearing any blue or green?), you will also want to consider what you will be comping onto. for example, if the object will be comped over a blue sky- it would be beneficial to use the bluescreen if possible.
 
RED has, due to its sensor, 200% more green sensors than blue.
So blue has half the resolution. VFX artists like resolution a lot for keys.
Furthermore blue has more noise than green. VFX artists dislike noise in the key channel.
So green is better.

HDCAM Camera heads (and all 709 cameras) have 4:2:2 YUV, or 3:1:1 YUV when using tape instead of uncompressed 10bit to disk, which is recommendable for greenscreens.
Therefore, also much more resolution in green than in blue for these cameras.

With HDCAM and RED the use of green allows better and easier keys.
If one needs blue (because the subject to shoot contains green i.e.) however a blue screen can work nicely as well, but requires more skill (and power) regarding the light and more tweaking in post.
 
Stephen Williams said:
Hi Jeff,

With film I strongly disagree with that as a blanket statement. I have been advised to shoot green many occasions, however when I shoot against both green & blue, the blue usually produces a better result. IMHO the overall color of the final composit should be taken into account.

Stephen
Click to expand...

With film there are good solutions (stocks) for green and blue.

However film is *much* more risky and slower than red for chromakeying, as one cant check at once if the key is perfect at the set, and cant control the pictures with suitable gear for shooting (wave/vector/histo etc) and film adds a grain layer which is annoying for keying. Also film is much more expensive for chromakey, especially when using the overpriced VFX-stocks.


With digital systems as red or hdcam (or generally any camera with a green-weightened CMOS or an YUV chromasubsampling reducing UV) green is the better choice.
 
the answer is clear!

the answer is clear!

if yo want to KEY OUT something with RED camera - what you will choose?

GREEN - of course :)


filip
 
Stephen Williams said:
Hi Jeff,

With film I strongly disagree with that as a blanket statement. I have been advised to shoot green many occasions, however when I shoot against both green & blue, the blue usually produces a better result. IMHO the overall color of the final composit should be taken into account.

Stephen
Click to expand...


Green has more luma information, even with many film stocks, but almost certainly if you're going to a DI process. It's inherent to the scanning process. But yes, there are times when blue is desirable. I guess the way I look at it is this: Always shoot green, unless you need to shoot blue.

I like to shoot blue if I'm compositing for moon-lit night exteriors, for example. You kinda have to shoot bluescreen if the talent is wearing green clothing (unless you want to let them wear blue, shoot greenscreen, then change costume colors in post).
 
laguun said:
With film there are good solutions (stocks) for green and blue.
.
Click to expand...

Hi,

In daylight I would favor F64D for Bluescreen, In tungsten 5212/5217 or Eterna 250T. I would never use a 500 asa stock.

With slow speed stocks blue always wins when I shoot a back to back test, I am not alone you can check out Geoff Boyles tests on CML.

Stephen

Edit, my tests always include smoke, glass & hair.
 
Jeff, I'm shooting interviews on a green screen and after viewing it there was noise in the green. Although the subject was fine. So my question is, will the noise in the green effect the key? I did a real quick key on one subject and continued to shoot more because I had good results.
 
Abu Reno said:
Jeff, I'm shooting interviews on a green screen and after viewing it there was noise in the green. Although the subject was fine. So my question is, will the noise in the green effect the key? I did a real quick key on one subject and continued to shoot more because I had good results.
Click to expand...

Some noise is OK, I think you will be fine if the noise isn't excessive. Play with some of the exposure and other controls and curves in RA / RC and see if you can clean some of it up that way first. If it's in the green, that's going to be difficult though. I would recommend not running any noise reduction, softening, sharpening etc.. until after you have done your keys. Set your proper WB and do a preliminary CC, get your black levels right.

Usually when I've seen noise on greenscreen when shooting with the R1 is if the screen was lit with tungsten and/or just needed a lot more light. Not that it matters after the fact. Your noise is probably mostly in the green or monochromatic on the green channel in this case. Layering a few chromakeys and a lumakey or two and trimming off most of the excess greenscreen with a garbage matte will probably do the trick. In extreme cases, there's always hand-roto. :) Be sure you're judging your noise by viewing your footage at full res, full debayer in RC / RA. You may have to transcode your footage using a full debayer, which will take a lot longer, if you are not already doing so. A full debayer can help, it's not uncommon for half debayer to amplify noise.

If there is noise in your subject, it can be to your advantage to not use a garbage matte so you can preserve some of the background noise on the greenscreen. That way you may be able to keep noise even across the image after comping in other elements. Or shoot a noise plate -- an evenly exposed black background that will mostly crush out when graded to match your footage, except you will have noise preserved that you can overlay onto comped elements / CG / whatever, so you can match the actual noise characteristics of the R1.

A little bit of noise to rough-up the 4K image can sometimes add a nicer more organic look.
 
Ramis said:
P.S: We'll be shooting with rain effect, not in the wide shots , (3 D will be used for that purpose), but in close-ups, as far as I know, you're better off using a black background and a back light as usual, but ha ha!! Blacks and Red one .... it does not sound as a good idea to me .
Click to expand...

Good luck ;-)

Keying raining water from greenscreen is, eh, challenging to say the least. Black BG and backlight sound like a more viable option to me, regardless of shooting medium.

Anyway, if i were you, i'd be prepared to do 3D rain in closeups too.
 
Jeff Kilgroe said:
I would recommend not running any noise reduction, softening, sharpening etc.. until after you have done your keys. Set your proper WB and do a preliminary CC, get your black levels right.
Click to expand...

Hi Jeff,

I wouln't even white balance the shots. I would develope at 5.000K and push it in RC just that much that the noise is hardly visible and a one-click Keylight key brings a sufficient result to start with.

Even though a tungsten lit GS doesn't look green anymore in 5000K it contains tons of green. If you WB it to make it look green for the eyeball you actually process the pixels before you pull the key which is in most cases not a good idea.

There have been test by Gunleik, Concrete and others wich showed that the Red tools are not great for WB tungsten footage if low noise is desired. You are much better off to develope at 5000K in RA/RC and do WB later in a dedicated CC app. or compositor.

If there is still noise that is so distrcutive that is has a bad impact on the key The Foundry's Furnace "Denoise" is the industry standard in compositor apps. to finetune footage in this regard. Unfortunately you cannot get "Denoise" for AE.

Hans
 
Hans von Sonntag said:
I wouln't even white balance the shots. I would develope at 5.000K and push it in RC just that much that the noise is hardly visible and a one-click Keylight key brings a sufficient result to start with.

Even though a tungsten lit GS doesn't look green anymore in 5000K it contains tons of green. If you WB it to make it look green for the eyeball you actually process the pixels before you pull the key which is in most cases not a good idea.
Click to expand...

Yeah, all true... For "white balance", I always start out at 5000K in RC / RA, regardless of what the camera was set to when shot. Actually I almost always keep the camera set at 5000K anyway as it's all just meta.

As for preliminary grades in RC / RA, depends on the workflow. For most workflows going to ProRes or similar, it can often be necessary. All depends on the footage and trying to balance between what is best to do later and what must be done in the RED tools to minimize loss going to a 4:2:2 conversion.
 
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