Severely noisy footage with good exposure

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TORM3NTO

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Severely noisy footage with good exposure

PostSat Nov 25, 2023 12:47 am

Hi everyone,

I'm really struggling to understand why I'm getting such grainy footage on my pocket 6k. I didn't have this issue before but now it comes up in any situation, lighting scenario and ISO.

In the frame I uploaded as you can see there is plenty of light.
https://easyupload.io/b291s6

ISO: 800
Aperture: f4.5
Shutter angle: 180
I really can't understand why it's so noisy to the point of being unusable. The same level of noise when ISO is at 1250.

What could it be?
Last edited by TORM3NTO on Sat Nov 25, 2023 1:01 am, edited 1 time in total.
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rick.lang

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Severely noisy footage with good exposure

PostSat Nov 25, 2023 1:00 am

Which Pocket 6K? You should avoid exposing any Pocket 6K or 4K at ISO 800. Stay with ‘native’ ISO 400 for the base range. Or try ISO 1250 in the higher range.
Last edited by rick.lang on Sat Nov 25, 2023 1:03 am, edited 1 time in total.
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TORM3NTO

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Re: Severely noisy footage with good exposure

PostSat Nov 25, 2023 1:01 am

Thank you for replying. The first Pocket 6k.
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rick.lang

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Re: Severely noisy footage with good exposure

PostSat Nov 25, 2023 1:15 am

I use the BMPCC4K up to ISO 1600, but exposing for ISO 1250 is cleaner. If you have sufficient light, ISO 400 is likely your best choice.

You can minimize the noise in post using your DaVinci Resolve Studio, but that is an extra time-consuming step and takes some experimenting to get to where you want your image to be. Suggest shooting some brief footage and breaking it into small clips with different noise reduction settings.
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roger.magnusson

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Re: Severely noisy footage with good exposure

PostSat Nov 25, 2023 3:15 am

Looks underexposed to me. Even cranking it up another four stops (overkill maybe) doesn't overexpose the window. Rick is right about ISO 800 on this camera, best avoid it in a scenario like this. Plus, you're shooting at 60fps which will require a lot of light.
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TORM3NTO

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Re: Severely noisy footage with good exposure

PostSat Nov 25, 2023 8:09 am

I appreciate both of our replies. So you suggest that in that instance, it was preferable to choose ISO 400 (which I can technically go back to in the da vinci raw tab, or is it not the same thing?) and instead open up the aperture (making the depth of field more shallow) or alternatively choose ISO 1250, more narrow depth of field and if needed some ND to avoid clipping the highlights?
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rick.lang

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Re: Severely noisy footage with good exposure

PostSat Nov 25, 2023 3:13 pm

If you expose that shot for ISO 400 and shoot at 24 fps or 30 fps, your sensor will gather at least 2 stops or 4x more light and reduce any sensor noise. Your highlights will likely not clip. That’s not the same as pushing the exposure in post which doesn’t reduce the sensor noise in the image. Best to get the captured image looking good.

Adding ND filters shouldn’t be required in this shot and if you add them you are reducing your interior exposure. If the shot had very important information in the exterior portion that you wanted to retain, you would cover the window with a gel or perhaps a scrim to reduce the intensity of exterior light only.

But that may not be needed because DaVinci Resolve may also help you retain details in the exterior. You can reduce the highlights in the frame largely independently of the normally lit areas. I grade everything now using the HDR colour primary wheels which let you control Black, Dark, Shadow, Light, Highlight, and Specular regions.

Be cautious when reducing highlights if you’re not going to reduce the normally lit areas or you will suck the life out of your faces. Just an example (not a rule as each scene is different): if you reduced Highlights one stop to affect the exterior portion of your frame, you may need to decrease the Light a quarter to keep some modeling of light on the face.
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CapraObscura

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Re: Severely noisy footage with good exposure

PostTue Nov 28, 2023 3:23 am

TORM3NTO wrote:I appreciate both of our replies. So you suggest that in that instance, it was preferable to choose ISO 400 (which I can technically go back to in the da vinci raw tab, or is it not the same thing?) and instead open up the aperture (making the depth of field more shallow) or alternatively choose ISO 1250, more narrow depth of field and if needed some ND to avoid clipping the highlights?


To go a bit deeper on this...

Shooting at 800 and reducing to 400 in post is not the same as shooting at 400. When shooting at 400 you're shooting at a native ISO. Anything above that, up to another native ISO, will introduce noise in the final image.

The simplest explanation for this is that any noise from the sensor will end up in the saved file. When you lower the ISO in post you're not REALLY lowering the ISO, you're essentially making a complicated exposure adjustment. This doesn't change the amount of noise, just the brightness of the image. Non-native ISOs introduce noise because they don't really exist. That is, the sensors artificially boost the brightness to achieve non-native ISOs.

That's why you almost always want to shoot at and expose for a native ISO. If that involves shooting high with ND then that's what it takes.

Note that I am not an expert. The above is an idiot-tier explanation with zero technical knowledge. It's all guidelines, not an in-depth explanation of why any of these things happen.
capraobscura.com for all of your questionably skilled photography needs
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rick.lang

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Severely noisy footage with good exposure

PostTue Nov 28, 2023 5:17 am

Although I often shoot at ISO 1600 on the BMPCC4K due to lightning for which I have no control. Today’s shoot was a breath of fresh air as the lighting was designed at my request and I was able to shoot at ISO 400. Looking forward to editing that video!
Last edited by rick.lang on Wed Nov 29, 2023 12:08 am, edited 1 time in total.
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Howard Roll

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Re: Severely noisy footage with good exposure

PostTue Nov 28, 2023 8:16 am

CapraObscura wrote:Shooting at 800 and reducing to 400 in post is not the same as shooting at 400. When shooting at 400 you're shooting at a native ISO. Anything above that, up to another native ISO, will introduce noise in the final image.


For Braw they are one and the same. Shooting 800 is actually underexposing by a stop so there's going to be more noise if exposing, and or lighting, for 800 as a function of underexposure.

Further one can't really look at log footage and make any real observations about noise. Once the footage is properly transformed (at native ISO) most of the noise is going to get buried. Sure there's a little noise here but overall the exposure could easily have been a couple stops higher. Definitely nothing I'd categorize as "severely noisy".

Good Luck

400.jpg
400.jpg (769.33 KiB) Viewed 768 times
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Theo Ribeiro

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Re: Severely noisy footage with good exposure

PostWed Dec 06, 2023 10:29 pm

I just went on a job and got incredibly noisy footage shooting at 3200 ISO on my Blackmagic Pocket 6k Pro. Much noisier than I usually got at that ISO range.

I did some tests, and even after sensor calibration, with a black cap in front of the lens, the image at 3200 ISO is pure noise.

I had just upgraded to the latest firmware (Blackmagic Camera 8.4 Update) before the job.
Today, I downgraded my camera to firmware 7.9.1, calibrated the sensor and the noise is gone.

3200 ISO is fairly clean and there isn't an issue anymore.

I believe there is an issue with the latest firmware versions though I don't know at what version that problem started. Maybe it's the same issue the OP is having?

I will try and do some further testing and maybe make a new post regarding the firmware issue but I can pretty much confirm that there us a serious issue that is firmware related at least regarding the Pocket 6k Pro.

Currently with firmware 7.9.1 Images at 3200 are good. Generally they are noisier than at 400 but perfectly usable (as they always were).
Last edited by Theo Ribeiro on Wed Dec 06, 2023 10:43 pm, edited 1 time in total.
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ShaheedMalik

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Re: Severely noisy footage with good exposure

PostWed Dec 06, 2023 10:38 pm

If you have noisy footage that means your exposure isn't good. You need more light and if you need more light, you need to move up to ISO 400.

ISO 200, 400, 800 is like a gain setting.
Gain -2, 0, 2+ for example. The more you turn it up, the more you introduce noise into the image. Yes, you can change the ISO in post, but if you exposed for 800 and you turn it to ISO 400, you won't have enough light.
Last edited by ShaheedMalik on Wed Dec 06, 2023 10:43 pm, edited 1 time in total.
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Re: Severely noisy footage with good exposure

PostWed Dec 06, 2023 10:39 pm

Howard Roll wrote:
CapraObscura wrote:Shooting at 800 and reducing to 400 in post is not the same as shooting at 400. When shooting at 400 you're shooting at a native ISO. Anything above that, up to another native ISO, will introduce noise in the final image.


For Braw they are one and the same. Shooting 800 is actually underexposing by a stop so there's going to be more noise if exposing, and or lighting, for 800 as a function of underexposure.

Further one can't really look at log footage and make any real observations about noise. Once the footage is properly transformed (at native ISO) most of the noise is going to get buried. Sure there's a little noise here but overall the exposure could easily have been a couple stops higher. Definitely nothing I'd categorize as "severely noisy".

Good Luck

400.jpg


Exposing the picture for 400 is totally different from exposing for 800.

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