# Question about noise threshold in 3.0

**URL:** <https://blenderartists.org/t/question-about-noise-threshold-in-3-0/1354392>\
**Category:** Lighting and Rendering\
**Created:** [January 14, 2022, 8:55pm UTC](https://blenderartists.org/t/question-about-noise-threshold-in-3-0/1354392 "2022-01-14T20:55:00Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Tokamak](https://blenderartists.org/user_avatar/blenderartists.org/tokamak/32/461091_2.png) [@Tokamak](https://blenderartists.org/u/Tokamak)\
**Post date:** [January 14, 2022, 8:55pm UTC](https://blenderartists.org/t/question-about-noise-threshold-in-3-0/1354392/1 "2022-01-14T20:55:00Z")

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Sorry if this has been answered elsewhere, but I haven’t been able to find it with the search terms I can think of.

In Blender 3.0 cycles: "The recommended workflow is now to set a noise threshold (instead of number of samples), and let Cycles adaptively refine the image until the denoiser can eliminate the remaining noise. "  
[https://docs.blender.org/manual/en/latest/render/cycles/render\_settings/sampling.html](https://docs.blender.org/manual/en/latest/render/cycles/render_settings/sampling.html)

How am I meant to do this? I have a noise threshold set, but Blender still always uses the exact amount of samples I have specified. Everybody says that the noise threshold lets Cycles automagically determine the samples needed, but I can’t get that feature to work.

What am I doing wrong?

 ![image](https://blenderartists.org/uploads/default/original/4X/d/c/1/dc132b1b24f032775c46b59adc1304cf4791c8bc.png)

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**Author:** ![DNorman](https://blenderartists.org/user_avatar/blenderartists.org/dnorman/32/24845_2.png) [@DNorman](https://blenderartists.org/u/DNorman)\
**Post date:** [January 14, 2022, 11:29pm UTC](https://blenderartists.org/t/question-about-noise-threshold-in-3-0/1354392/2 "2022-01-14T23:29:56Z")

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I think you have to set a time limit in the render tab for it to work.  
In the render tab 0 sec disables the time limit.  
Edit:  
If you hover over the time limit in viewport and render tabs you will see (tooltip) that 0 acts differently, for viewport it sets an automatic limit and for render it disables the limit.

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**Author:** ![Tokamak](https://blenderartists.org/user_avatar/blenderartists.org/tokamak/32/461091_2.png) [@Tokamak](https://blenderartists.org/u/Tokamak)\
**Post date:** [January 16, 2022, 4:09am UTC](https://blenderartists.org/t/question-about-noise-threshold-in-3-0/1354392/3 "2022-01-16T04:09:24Z")

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I’m still clearly misunderstanding something. These are my settings now:

![image](https://blenderartists.org/uploads/default/original/4X/f/5/d/f5df1f939f118d8754de5d85e609d69e52e986d8.png)

But when I render, it doesn’t stop at 10 minutes, but just hums along until it’s done 800 samples, regardless of how long that takes.

What am I missing/misunderstanding here? I’m confused.

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**Author:** ![DNorman](https://blenderartists.org/user_avatar/blenderartists.org/dnorman/32/24845_2.png) [@DNorman](https://blenderartists.org/u/DNorman)\
**Post date:** [January 16, 2022, 1:27pm UTC](https://blenderartists.org/t/question-about-noise-threshold-in-3-0/1354392/4 "2022-01-16T13:27:28Z")

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It should stop a little after the time limit. The time limit, limits the ray tracing time and does not include other calculations such as building and de-noise.

Here I set the limit to 40 seconds, with de-noising it took 57.67 seconds and rendered 20 samples.

 ![Time](https://blenderartists.org/uploads/default/original/4X/5/f/9/5f9803ec4011244090ff6c2fa187926ae8e88c53.jpeg)

With de-noising turned off it took 43.69 seconds but still did 20 samples. The 3.69 seconds extra is the building time before it starts rendering. The limit refers only to ray-tracing time not any other calculations build, de-noise, composite etc.

Your 800 samples should be “ray-traced” in 10 minutes, the extra is due to additional calculations (before and after).

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**Author:** ![Tokamak](https://blenderartists.org/user_avatar/blenderartists.org/tokamak/32/461091_2.png) [@Tokamak](https://blenderartists.org/u/Tokamak)\
**Post date:** [January 16, 2022, 6:05pm UTC](https://blenderartists.org/t/question-about-noise-threshold-in-3-0/1354392/5 "2022-01-16T18:05:10Z")

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Oh! I get it. Looking at the image metadata, all of the renders of various frames are all about 10 minutes. The metadata still says the samples are “800”, but I gather that’s just listing the max samples value.

Thanks for explaining this to me! 🙂