Problem with grain

[Vado]

I need your help guys. I swithced scene from vray to corona and trying to render it but I cant get rid of grain. Have a look at the picture, time of rendering and passes. I will add all info you will ask for. There is just HDRI map in enviroment slot and few recessed IES spotlights. except of grain there is a lot of fireflies also

[romullus]

Looks like your curtain material has refraction greater than 0 and most likely there's glass panes in windows with refraction mode set to solid. Fix this and you'll get rid most of the noise/fireflies.

[racoonart]

From what I can see here, your noise/fireflies are most likely to come from your ies light sources. Try to use them without ies files for now since these are extremely slow/noisy currently (you can use standard photometric lights in the daily builds which work a lot better, but that's not possible in A5).

Another thing would be wrong glass mode for the window material (as romullus said). You can also try to use a portal in the windows which will speed things up quite a bit.

[Vado]

Looks like your curtain material has refraction greater than 0 and most likely there's glass panes in windows with refraction mode set to solid. Fix this and you'll get rid most of the noise/fireflies.

I found out material converter converted all Reflection and Refracion levels to 1 so your hint should help but at the moment it didnt. I am still trying to find whats wrong there

[racoonart]

I found out material converter converted all Reflection and Refracion levels to 1

If it's not correctly converting the original material you should post it in the converter thread, best with a matlib file (1 example) of your base material.

[Vado]

I found the problem, there was an enviroment object behind the windows and there was used emiting light material which caused that grain. Glass, IES and everything else was quite ok, I will try to use standard photometric lights instead of IES to speed it up a bit, will post result here....actually I have A5 so photometric lights doesnt work so I used IES anyway