Increase Sun size increases noise

[herncabret]

Does anyone know why increasing the size of the Sun to say size 4..5 causes issues with noise.
It is an external scene in 3ds max that also uses a hdri environment.

There's no issue when I use the Sun on size 1 or the environment on its own.

Thanks.

[maru]

Hi, can you post any examples of this?

[sprayer]

we need to see render and scene, but then you increasing size of light source it light with more soft shadow what at early stage of rendering gives more noise because rays more spreading, you can change directionality to make more focus shadow = less noise

[maru]

There is no directionality parameter for the sun, and also increasing directionality usually does actually introduce more noise. ;)

[sprayer]

I just said about other light source for understanding, i know sun is almost "direct" light =)

Never saw much noise with directinality, what will produce noise at strong shadows?

[Darawork]

Hi,

I find this happening here too; increasing the sun size leads to a vast increase in fireflies. Attached is a screengrab of a  scene with the Corona Sun set to a size of 32. You can see the noise welling up in the glass walkways. The areas where the noise does not well up are because a Coronabitmap of a grid is plugged into the Refraction Glossiness node.

Decreasing the Corona Sun size back down to 1 gets rid of all fireflies and noise.