Noise & exposure

[huascar]

Hi everybody.
I'm trying to understand well how to control exposure and noise, shooting with R1. Here's my setup:

Red One Camera Build 20.1.6
Nikon mount with Nikkor 50mm f1.2
4K 2:1 redcode36
one 1kW tungsten light (with CTB gel)
two 1200w HMI fluorescent daylight (4400k) homemade

I open all the footages with RedCine 20.0 exporting Apple ProRes422 HQ movs.

I'm shooting a chinese gold cat doll (with swinging harm) on a black piano. I want to achieve a good lighting and good exposed image. The two HMI are in front of the piano&cat and the tungsten gelled as rear light.
I calculate exposure on cat using either zebra and false color. In some of the black parts of the piano I have some purple zones (false color).
When I export a mov from RedCine I have some noise all the black zones.
So I have to overexposed the cat, then raise down ISO in RedCine, adjust exposure to obtain less (quite none) noise in black zones...


There's something wrong with light?!?!? The cat is on the piano, and the two front HMI lights are about 1 meter away. There's a lot of light?!?!?!

Sure, I'm not speaking about A LOT of noise... but I want to achieve the best image possible from my Red....

Thanks to everybody


huascar

 

[Casey Schendel]

Could be a few different things. What build are you on first of all?

1: Don't take this the wrong way but are you exposing the image from the lens or from the exposure controls in the video menu?

2: Could you post a screen grab of the footage and your setting from red alert for us to take a look at?

3: You could always over expose the blacks then darken/contrast them in post which should eliminate all grain.

 

[huascar]

In a still is less visible, but at 25fps is present.

 

[Michael Epple]

You black zones look like dark grey zones. If you print down your dark areas it will also decrease the noise. If you don't want black in your black zones then you have to model the light to make your exposure work.

 

[huascar]

What do you mean with "print down the dark areas"?!

Raising down exposure/curve/ISO in RedCine?

thanks

huascar

 

[huascar]

Again, it's so difficult to understand how FALSE COLOR & ZEBRA work.

I shoot always RAW, open the R3D files with RedCine 20.0, export a TIFF frame, put in a Final Cut sequence and monitor it trough a firewire vtr on a JVC broadcast SD monitor.

What I see in RED LCD or EVF is quite different from what I see on my computer monitor and broadcast monitor (via firewire).

When I expose using FALSE COLOR, I try to have not beyond yellow areas and no purple areas. It seems to be well exposed. When I see it in my computer (or firewire) it's always more exposed...

And also the ZEBRAS. How does it work?! In the last years I used only ONE zebra to control the exposure: I set 80% (or 100%) and I knew when zebra appeard I was clipping. Why TWO zebras?! And why I have the zebra limits?!?!

I'm sorry for the several question, but I'm going crazy!!!

huaascar

 

[Casey Schendel]

The image you posted doesn't seem to have any grain or noise in it? I don't know whats wrong. The only place I think you might see grain is that back grey wall.

You can just add some contrast/curve to the footage and your blacks will be stark with no noise if in-fact there is noise there.

 

[huascar]

UPDATED!!! new noise tests

UPDATED!!! new noise tests

Hi, yesterday I spent a lot of time to understand better how to work with FALSE COLOR to avoid noise in low light scenes.

My results bring me to work in this way:
for dark areas YOU CAN'T HAVE ANY (almost) PURPLE AREAS. Purple=noise!!
for highlight areas WHERE YOU HAVE YELLOW (THEN ORANGE AND RED) YOU ARE CLIPPING! So you can have a little area with orange/red (maybe where a direct light "touch" a face) but not more.
Following this rules I obtain good results. Good means "what I see with FALSE COLOR is what I'll have on post.

Now I'd like to understand well how color correction works on dark areas, and what it does on noisy areas. In my pics you can see that an almost noise-free image becomes better (no noise) if I use curve, shadow and contrast settings. It seems that this settings help the image to be noiseless. It is true? So if I have an image with noise I can truy to decrease it raising up the dark mood. Right?



Anyway, here's my test. I hope they are clear.


Thanks to everybody


huascar