- August 9, 2020 at 7:13 pm
I’m looking at you Todd…looking for ideal settings for reducing noise for chroma key. Lower ISO but how low? Fstop 5.6 or higher. High shutter speed for reduced blur. Baked in gamma for reduced processing in post. Raise blacks in camera and crush in post. Don’t wear dark clothing.
We have good light and green setup but discovered the noisy blacks when keying. Just dropping key light on a clip revealed some bad noise in blacks. Another shot with light hair and clothes was a breeze. But dark shirt or coat was a noise fest.
Here’s my thought…ISO 400 FStop 5.6. Canon 709 gamma with blacks raised a bit. Shutter at 300 we are shooting 29.97. How about in camera noise reduction? Use camera noise reduction? Thinking 4 or 5. I can sharpen in post but we are shooting 4k and scaling down to 1080 so natural sharpening occurs.
Tilt Media Inc.
Video Production, Post, Studio Sound Stage
- August 9, 2020 at 8:24 pm
Most of your setting seem ok I guess… but I’m not gonna be a WHOLE lot of help. To be honest I’ve never really played hard-n-fast with shooting settings or establish a settings protocol for greenscreen work. Mostly I just shoot as if I was shooting anything else, I just make sure my screen is well and evenly lit.
A couple of your settings I definitely don’t do… I don’t shoot with a higher-than normal shutter speed… unless I”m specifically going for a “narrow shutter” effect (which is rare, if ever) I will still only shoot at a “normal” speed… one over twice the frame rate. I almost never shoot at anything other than 24fps, so for me my usual shutter speed is 1/48th. Of course I totally understand your reasoning… high shutter speed equals sharp images equals clean edges for a better key… I get it. It’s just that I hate the staccato narrow shutter look so much that I would literally sacrifice key cleanliness for more natural looking motion. But, I usually don’t have to, I’ve always managed to get pretty clean keys even with a normal shutter and fast motion… I think it’s more a function of having a really good keyer.
I’ll say the same for f-stops. I probably wouldn’t shoot as high as 5.6. Honestly, I’m a wide-open guy, and will frequently shoot as wide a f/1.3… I just like a shallow look. I know, “But there’s not a background to throw out of focus, so what’s the difference?” Well, even just a headshot of a person with no background looks radically different at f/2 compared to f/5.6. It depends on the circumstances and uses, of course, but often I like the sharp eyes with focus falloff as it goes back. I really (usually) really dislike a head shot that has razor sharp eyes, but also has razor sharp ears… I almost always prefer seeing the focus fall off a bit. Again though, I understand the theory… shoot with a higher f-stop for sharp edges and cleaner keys. But again, I don’t recall ever having too much trouble with edges keying well… again, I think it’s more about having a good keyer.
Through the many years we’ve tried about everything for keying, from Keylight to Ultimatte and everything in between… but for the last while (last few years) we’ve never used anything to key except the Ultra key filter in Premiere (or sometimes in After Effect). It’s just great. I almost never have to do more than just throw it on as a filter and give the eyedropper one click to set the key color. Nine times out of ten that is almost flawless… maybe just a few little tweaks are needed (usually pedestal and choke). I really like Ultra not only because it is so easy, but so controllable… it can easily key transparances… through smoke, or water, or preserve reflections on glass. That’s one way we’ve used it a lot, outside of car windows for driving scenes. It can pretty easily key cleanly and preserve, say, a driver’s reflection in the side window.
I will say though that, like you, hard blacks seem to be the occasional problem area…. sometimes you’ll see a bit of noise there. Last week we had a key that looked flawless in my own edit suite, but when my other editor opened it in his suite upstairs I could see some noise in the blacks on his monitor. The weird thing is, the monitor in my suite (which looked great) is actually a much better monitor that the one that looked a bit noisy in his suite. So… we had to adjust the key so that it not only looked good in the expensive monitor, but in the cheaper one, too.
There’s been a few times that I’ve had to stack keys, and consider one the “primary” main key, and one on top of it that one that more concentrates on preserving blacks and such. Very rarely we’ve had to use garbage mattes to put a black area back in on top, but fortunately that hasn’t happened often.
Rules and settings are a great thing as a starting point… to me though most of the time good keying and compositing winds up to be as much trial and error as anything else.
Fantastic Plastic Entertainment, Inc.
- August 24, 2020 at 4:35 am
“really dislike a head shot that has razor sharp eyes, but also has razor sharp ears… I almost always prefer seeing the focus fall off a bit”
That’s not going to work if the added background is in focus! Agree otherwise though.
Are you sure you need 300/s shutter speed? I’ve shot dancing at 150/s (and then added motion blur later in AE) and it turned out fine.
Neat video noise reduction before keying works wonders.
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