DSLR for green screen

S

Splin

New member
Hi,

as you guys seem to be knowledeable here I thought it could be good place to ask this question. I am considering to do some filmed green screen work with a dslr. Various cameras are available to me, from Canon side the 5DMark II and from Nikon side the D300s and D3s. I must say though that I love the picture from D3s which is gorgeous, but I am talking about the emotion, not so much the technical side. I have no idea what are the specific technical details between both companies. If someone could hook me up with some links where these subjects are debated to death I would be very thankful.
So, all I know is that one is h264, should be iframe technology and the other mjpeg which in theory should be better option since mjpeg has been around for some time in systems and keying solutions are known.

What are your opinions in the matter?

Thank you!
 
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You would be better off shooting a less compressed format for green screen. DVC Pro HD would give you the 422 color space you need for a decent key (if you shoot in less color depth, people and objects have much more stairstepping on their edges (that is why DV is not a great format for keying)). DSLRs have very shallow DOF which can cause people to have soft edges and that is not what you want when keying, you want nice clean edges. Add aliasing into the mix and you would probably be sunk. I will qualify these statements by saying that I have not actully tried it, but it stands to reason it is not ideal. If I were you I would rent an HVX200 and call it good. You would get 422 color, higher data rate and more DOF to make sure your talent's edges are sharp. If you have lots of time to do tests for free and bring an edit system on the set, I would be interested in seeing your results. I would not risk it otherwise.

I also have to ask if you know the basics of setting up a green screen shot (lighting the BG very flat, getting seperation between the talent and the screen, wardrobe, reflections etc etc etc). You should study this part hard as well.
 
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Some of those 7D are quite ok, the black and white I mean. Others are quite unacceptable.
My question was more about if someone has arguments which codec is better in its nature for that kind of work. And what could be the theoretical showstoppers.
I've been doing greenscreen work before with different cameras, starting from HVX to film and Red.
 
Splin said:
Some of those 7D are quite ok, the black and white I mean. Others are quite unacceptable.
My question was more about if someone has arguments which codec is better in its nature for that kind of work. And what could be the theoretical showstoppers.
I've been doing greenscreen work before with different cameras, starting from HVX to film and Red.
Click to expand...

Less compressed = better.

Whenever possible I actully take the HD-SDI feed out of my HPX-500 and record to D-5 tape then use that tape for our DS chromakey session. That is $$$ though.

Main thing is the larger color space. 4:2:2 is a minimum without special plugins and a steady hand. Shooting it right makes the most difference though.
 
Splin said:
Some of those 7D are quite ok, the black and white I mean. Others are quite unacceptable.
My question was more about if someone has arguments which codec is better in its nature for that kind of work. And what could be the theoretical showstoppers.
I've been doing greenscreen work before with different cameras, starting from HVX to film and Red.
Click to expand...

What was wrong with the second one video with the woman in the chair holding the baby? I put it on 720p and full screened it and it looked perfect to me (well the second key did. What am I missing? Only the first key of the video on the far left away from the actress was the only very small flaw I noticed in the key, but easily removed. The second key looked totally flawless to my eyes, accept that a real background was not used. The key itself though, I can't see a single thing wrong with it.

I don't see the black and white one looking any better really accept that it is using a real background for the key rather than white/light gray gradient for the background. I don't know what I am missing as far at the key quality goes, but if it's this hard to see I'm feeling it can't be so bad to be unacceptable....at least not to me.

Can you elaborate on what makes the second key from the second video "unacceptable" that I am unable to see?
 
skital said:
Here are some 7D Green screen test videos:

http://vimeo.com/7954098

http://www.youtube.com/watch?v=1ltDdXaJoT8

http://www.digital-negative.com/2009/11/7d-greenscreen-keying-test.html
Click to expand...

Those are very good keys, good job.

I think you had things like lighting, framing, motion, wardrobe and hair in a best case scenarios and that is not what I was expectiong someone to ask for. I would say that you mave have trouble in certain situations, but this is encouraging.

Thanks for sharing.
 
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