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Ok, Just what can i do with lighting in post?

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Josh BrineOk, Just what can i do with lighting in post?
by on Sep 14, 2012 at 1:31:58 am

Hi everyone, im a newbie at post. but projects are coming fast and i need to keep up.

i need an answer to understand just what the capabilities of post are.

i know enough about color correction, keying, roto (i actually enjoy roto, but its hard and timeconsuming)and im fairly familiar with 3d packages.

anyway.

I work with a team of people who have a 'dangerous' amount of knowledge, that is they know enough about the theory of post production that the term 'fix it in post' comes up over and over and over again, and im forced to remove, patch, add, and fix badly done and 'hurried over' shots. I need to know what is actually possible with relighting,

how far can lighting on set be left until afterwards. how much has to be done on set. how far can it be pushed? how exponential is the workload for post vs doing it on set. and how much pre planning needs to go into this sort of stuff?

i know this is a random series of quesitons lol. hopefully someone will be interesting in responding.

thanks


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Angelo LorenzoRe: Ok, Just what can i do with lighting in post?
by on Sep 14, 2012 at 2:52:24 am

Lighting has to be done 100% on set.

Sure, you can make overall adjustments or vignette something, or dodge something out with a track matte. You won't be able to make hard shadows soft or add a rim light in post. You may be able to balance intensity but you are left with the source, shape, and direction of lighting on-set.

Lighting ratios should be set on-set rather than relying on contrast enhancement in post, for instance. Just leads to weird inconsistencies.

Also, is your team paying you? If they aren't then dump them for a project or two and let them fall into better shooting habits... I've had to do the same for my circle of friends.

Angelo Lorenzo
Fallen Empire Digital Production Services - Los Angeles
RED transcoding, on-set DIT, and RED Epic rental services
Fallen Empire - The Blog
A blog dedicated to filmmaking, the RED workflow, and DIT tips and tricks


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Josh BrineRe: Ok, Just what can i do with lighting in post?
by on Sep 14, 2012 at 11:41:17 pm

Thanks for the quick response,

the truth is im often in situations i dont really have the experience to make swift decisions in, i kind of 'think' that x or y could be done better etc. but i cant offer a total solution fast enough, or be prepared enough to preemp what is asked of me.

in terms of being on set, what should i aim to look out for and pre-empt?

im only really talking conceptual. i know every effect is different, but the fundamentals are there.

especially im doing alot of keying lately, and im not sure how to best light the subject.


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Angelo LorenzoRe: Ok, Just what can i do with lighting in post?
by on Sep 15, 2012 at 1:18:32 am

Sadly, it comes with experience, and by experience I mean failure.

When you're a one-man band, you can't promise your production everything. Sometimes is cool being hero, the know-it-all, when it comes to sloppy shooting but I'd rather be the strict vfx guy who said "no, you can't do it that way, take 5 minutes to do it right" than saying "yeah, go for it!"

I have to say this: if you look through the lens and you aren't happy with the shot, change something on-set. It's like saying "don't wipe down that table, we'll do dust removal in post!" well which takes 30 seconds and which takes 10 minutes?

Another way of thinking about it, is can it be done in Photoshop? If you could relight an entire scene, photographers wouldn't be buying $20,000 strobe kits. You have to narrow the scope of that understanding a bit further because video complicates things, you're working with objects that can shift perspective.

When you're on-set, the biggest piece of advice I can give you is know how the greenscreen process works, independently of any software. You'll be armed with knowing how to reduce color spill, if a green screen is properly lit even in dark scenes, how and where to place tracking markers. There is about 50 years of keying history and technique to stand on, back to when it was done with analog signals and equipment.

Keying in the most base sense is using the difference in color channels (green vs red and blue) to help create a matte around the subject. There are more optimized ways to key footage than using a single Keylight filter and hoping for the best: You can split the scene up into multiple layers with loosely tracked garbage mattes so you can key different subjects differently, you can use core mattes to key the inside of the subject then use a more subtle key for the edges, or a combination of the two.

Make no mistake, you will have to clean up mostly all green screen shots with some rotoscoping or edge erasing because of high motion blur or other issues.

Angelo Lorenzo
Fallen Empire Digital Production Services - Los Angeles
RED transcoding, on-set DIT, and RED Epic rental services
Fallen Empire - The Blog
A blog dedicated to filmmaking, the RED workflow, and DIT tips and tricks


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Josh BrineRe: Ok, Just what can i do with lighting in post?
by on Sep 15, 2012 at 2:21:43 am

Yeah most of my work has been fixing badly shot scenes

so i feel like ive had a real crash course.

i often use two or three keys, garbage mattes, planar tracking and roto with mocha, and holdout mattes in AE.

but sometimes i just cant get a good key from footage that should be in my opinion easier then it seems, i still (as do we all) have lots to learn.

i have another post called girl green screen i posted a while ago with a snapshot of the current shot im working on.

im confident i will learn waht i need, but with the project leader being bold and confident, i really want to get a more grounded and solid understanding, if i cant present a solid do and do not list, then he is forced to simply try and shoot it anyway. anyway i digress.

i have found from failure, for example this current shot. that it may be a good thing to rim light, (dont know much about lighting, but this should/may accentuate the edges for a better key, as im getting dark halo's where the subject is not light along the edges


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Dave LaRondeRe: Ok, Just what can i do with lighting in post?
by on Sep 16, 2012 at 6:35:11 pm

[Josh Brine] "...im getting dark halo's where the subject is not light along the edges"

Aside from good lighting, the second way to drastically improve chroma keys is to use a better camera. It doesn't have to carry a 5-figure price tag, but it does need to have good color resolution or color sampling.

One example: the venerable Panasonic HVX 200, at $3800 new. It records in the VDCPro HD codec, which is good for chroma keying.

So to give you a straight answer, we'd have to know what you're currently shooting.

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Josh BrineRe: Ok, Just what can i do with lighting in post?
by on Sep 17, 2012 at 3:59:05 pm

Hey dave thanks for the response,

im shooting on a 5d mk III


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Dave LaRondeRe: Ok, Just what can i do with lighting in post?
by on Sep 17, 2012 at 6:05:03 pm

Ah. That means it H.264 footage. 4-2-0 color resolution (aka color sampling).

Think of a video signal as having two components: the black & white picture and the color overlay. The two components can be, and often are, at different resolutions. This is done to reduce file size, and the resulting image is good enough to fool the human eye, but not a computer.

In the case of H.264, the color overlay is 1/4 the resolution, and is blown up to match the B&W component size when viewed.

Ever see how bad video looks when blown up? Even to the human eye? Now, imagine how a computer sees it. And what do you need for a good COLOR key? Accurate colors, perhaps?

This doesn't mean you can't get an okay (not great)key with H.264: it can be overcome somewhat by outstanding lighting... but then undone again if the camera uses sharpening settings.

And since nobody knows how this stuff was shot -- you may not know yourself -- you might be stuck with bad, useless video.

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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