Exposure Question

[Caleb Spillyards]

Hey guys ive been wondering about some best practices. If I wanted an image (say an medium shot of an actor) to be exposed properly from one side but deep enough contrast on the other side that that side of his body/face fell into complete black, is that something i should still expose good enough for to see detail and just crush in Post? In other words, if that side of the actors face or features are clipped, should i slightly fill in that side of his face to get the detail there and then just crush in CC? Ive just been troubled about the best way to go about it. It feels like on the shoots where ive filled in those areas, the darks dont get dark enough without effect parts of the image i dont want them to etc. Does that make sense?

Caleb

 

[ericyoung]

Depends on what tools you are using to do the crushing. If you have secondary windows, it's easy to pick and track areas to crush separate from the overall frame.If not you could experiment with curves and/or gamma, rather than just brightness (which sounds like what you are doing).However, if you know for certain that you won't want ANY detail in the dark side of your actor, then you don't necessarily need to add fill. Just let it go to black in camera. Just be aware that if there is no fill & post crush, then potentially there will be visible noise in your shadow areas.

 

[Phil Holland]

Depends on intent. This sounds more like a lighting question to me. If you are going for a low key look with a lot of dark masses I'd solve if via lighting control and contrast on the day. If you want a big of texture or detail in those deep shadows certainly add fill.

Barn doors, flags, and say black wrap might be the good way to go if you want a pure black. Like Eric said, once the detail is gone it's gone. Lighting really is always about making those decisions though.

Heh. Which puts a lot in contrast to the last thing I shot where literally everything was illuminated via very soft light.

 

[Caleb Spillyards]

thanks for that guys. Yeah the issue i run into when things are underexposed is that theres a ton of really gross noise. Eric were you saying that if things are underexposed and i crush them in davinci thats what causes the noise? as opposed to crushing an area thats shadow but still has detail? im trying to get deep blacks without all of the noise. In the case of under exposure (say for shooting a night scene) should i use windows to get the contrast i want out of things that do have detail (people, foreground, elements etc) but leave back ground details that are under exposed alone? thanks for taking the time y'all!

 

[ericyoung]

The only way to avoid noise is to expose those dark areas so detail is slightly brighter the noise floor. There needs to be exposure separation if you want to separate the two. Then when you crush the noise to pure black in post, you will still see some detail in the shadows which is not noisy.If you don't care about shadow detail, then you can crush further to lose the noise and the shadow detail amongst that noise.

 

[Phil Holland]

Noise in the deep shadows, darks, and black areas are caused pretty much by lifting or not "placing" that where it should be. If you want to be able to see detail without noise you'll need light on that stuff. It's one of those "if you want to see it light it" things. If you don't, let it go into the darkness.

Couple shots to illustrate.

Crushed blacks, where they have been pushed is pure black and will not have any detail or noise:

Deeper shadow detail aided by an additional light, in this case gelled with a steel blue filter.

If I recall correctly, a 5 light setup to help illuminate the darker textured leather shirt and brought down in the grade.

Deeper and pure blacks with separation. Rest of the room was under exposed, but with light on the subjects in the BG to give them some life, but not distract from the subject.


If you take a look at the most recent Underworld feature film that was shot on Epic they had a tremendous amount of folks in black leather, however they were able to have a good bit of separation and detail via a combination of the lighting and the grade. Not a lick of noise because what was desired to be seen was lit and brought down later to give it a crushed look.

 

[Caleb Spillyards]

That's all great info, but for a night shoot where you literally can't light everything, the underexposed areas should be windowed off when you lift shadows so that the underexposure doesn't get lifted causing noise? Sorry for all of the questions, I just want to be able to get silky blacks and this is plaguing me haha

 

[Phil Holland]

Ah. I think I have a clearly picture on your situation. I don't know the environment or set situation, but what I would likely do is something a bit more directional with a keylight on your subject/subjects. Flag it off to protect other areas from being hit by it. I would utilize "something" to get a bit of light on anything else that you want to be visible.

Depending on the set, I would add a backlight. Perhaps even adding some spice to the situation by involving LEDs or even flashlights. You want to do your best to carve out those silhouettes and add the key on your subject where needed. You'll end up having a good deal of black masses, which will induce that darker night feel.

 

[JR Monteiro]

So let me get this straight. When I have pure black under exposed areas in my shot I will have noise just in the black areas unless I crush those black in post below the noise threshold. Is this accurate? In fact what I am hearing is that to get rid of the inherent sensor noise i must crush all blacks a little in post. This has concerned me recently since I have started paying attention to the little red noise bar to the left of the histogram on my Epic LCD. Unless I expose my blacks at about 10 IRE, I see the noise bar kick in. i like to create a full dynamic range shot in camera from 0% IRE black to 100% IRE white. I guess this is not the best approach with the Epic because when I do this I always see the noise bar kick in. It seems to increase or decrease, based on the percentage of black in the shot, no matter what ISO I shoot at. So I guess the only way to eliminate the noise altogether in camera is to open up the iris or add light so that the blacks are maybe in the 10%-15% IRE range. Then bring them down to taste in post without consideration for noise issues. Am I just being paranoid? Does that noise carry over into the brighter areas of the shot as well?

 

[Phil Holland]

This has concerned me recently since I have started paying attention to the little red noise bar to the left of the histogram on my Epic LCD. Unless I expose my blacks at about 10 IRE, I see the noise bar kick in. i like to create a full dynamic range shot in camera from 0% IRE black to 100% IRE white.

The short answer, and I'll do my best, is keep in mind you are dealing with REDCODE Raw. The bar on the left of the histogram is indeed the noise meter for your underexposed shadows. That's information that's going to contain noise in it if you lift it up at all and likely doesn't contain much detail. It's underexposed and out of range at the point. There's a bit of a safety net there and that's why the bar fills up. If it's peaked, there's likely no usable information.

Now keep in mind this isn't just a Red thing. That's sort of an all camera thing. Whatever is past that point is likely not retrievable. If you are just seeing hints of the shadow noise bar filling up you may be fine, but it all depends on your shot and the content of your frame in reality.

The same rings true for the clipping bar on the right and also the "stoplights". Those let you know where you're having problems in your highlights and where you could potentially be losing information/detail.

Those tools are there to inform you. If you have a scene with deep blacks that you want crushed and you know that or lit for that effect, there's not much of a concern. If you want to see anything there and have rich shadow details you'll need to expose differently or add some fill to your scene in those areas.

I view the histogram as a bucket. Too far to the left or right and your going to spill out your water. Personally I expose and light for raw. Sometimes I may favor exposing to the right a bit with the intention of pulling things back down in post so I have some nice meaty shadow detail. Then again for low key work, I might not do that.

The way I look at it is properly expose your raw material and you can do damn near anything with it later on. You'll be able to "create a full dynamic range shot in camera" if it's properly exposed and within reason is properly lit. Again, true for all cameras in reality.

I guess I should add, every scene has different "dynamic range". It's what you are choosing to capture that matters. If you are lighting your scene from scratch that's the most control you'll have. If you are say attempting to shoot and expose for skin tones while shooting up at somebody while they are silhouetted by the sun you may be faced with a scene with well over 30 stops of measurable dynamic range in frame relative to your chosen exposure and you will be picking and choosing your battles at that point. What do you want to see? What are you okay losing? Getting familiar with NDs and things like Low Contrast Filtration can assist in certain situations like harsh daylight. That's more about building a tool set of knowledge from shooting though.

 

[David Mullen ASC]

If you don't want any shadow detail then just shoot at an ISO setting that gives you the noise level you want and make the blacks black in color-correction and don't use fill light. Noise comes from either a high ISO setting and/or lifting underexposed areas of the frame to bring them out, so it's not a problem if you don't want detail there anyway. Adding a bit more fill is only necessary if you plan on crushing the blacks a bit to make them denser but still want some shadow detail, so you compensate by lighting a bit lower in contrast because you are adding contrast in post.