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green screen settings SDX900


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#1 rsellars

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Posted 03 December 2007 - 07:56 PM

I've shot a fair amount of HD greenscreen - first time shooting SD in a while. Any recommended camera settings for the SDX900 as far as detail, coring, gamma, knee compression, etc. I know that noise is an issue to be avoided, so should I avoid the cine gammas and use a normal gamma? Also, will knee compression add too much unwanted noise? A little knee compression might help with product highlights. I know that I should avoid detail - can I go below "0"? Of course it can be sharpened in post - but how much without looking weird?
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#2 Michael Nash

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Posted 04 December 2007 - 04:16 AM

Knee compression doesn't contribute any noise to the signal, although different gamma and black stretch settings might. But unless you're using + gain settings, you shouldn't really have any unwanted noise with any of the gamma settings on the SDX. The nice thing about video is that "what-you-see-is-what-you-get," meaning whatever noise level you see on a properly tuned monitor while shooting will be the same noise level you experience in post. If you feel that your gamma settings are making the signal too noisy for your taste, you can switch your gain to -3db to mitigate it a little.

I've used the color correction menu to crank up the green saturation for green screen in conjunction with "Filmlike" gamma settings, and not suffered any ill effects for it in post. But as always, test for yourself to see what settings look right to you.

"Zero" detail level in PAINT>ROP>MASTER DETAIL is nominal level; negative values reduce detail enhancement even more. You can also make the detail ehnancement outline line "thinner" by increasing the value of the H. DETAIL FREQ in the low/mid/hi settings. There's no rule that says you have to avoid detail enahncement when shooting greenscreen, and in fact standard def usually benefits from a little detail. But again, what you see on a properly tuned monitor (which means tuning the "aperture" level in the middle) is what you get.

Oh, and be sure to record in DVCPRO 50 mode for the best quality comp.
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#3 Richard R. Robbins

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Posted 04 December 2007 - 06:21 PM

Is there any truth to the thought that you should shoot the foreground element in 30p rather than 24p? (especially when editing with a 29.97 timeline)

Rich
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#4 Michael Nash

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Posted 04 December 2007 - 08:16 PM

I think that notion applies mostly to matching the pulldown cadence between your foreground and background elements. If they're both 24P over 60i (with a 3:2 pulldown), there's often no easy way to match the "A" frame between the elements. If the cadences don't match you might see some odd motion artifacts between them, and you certainly won't be able to extract a "clean" 24P composite should you need to.

So one work-around is to shoot/create both elements at 30P so all frames match, and you often don't notice the subtle difference between 30P and 24p. Another route is to shoot both elements in 24P"A" and remove the pulldown, composite in true 24P, and convert it to 60i later.

Edit: All that said, people have been compositing telecined film elements with a 3:2 pulldown for years, so it's not necessarily the end of the world if you do it that way.
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#5 rsellars

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Posted 05 December 2007 - 10:07 AM

Michael,

Thanks for your suggestions. I appreciate the help. Good idea about the H frequency detail. I'll look at that.

Randy
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