Just a “simple” question i would like to know which is a nice level limit to use?
thank you
5%… from my tests.
Me personally I don’t have the time to wait until images are super clean but rather switch on a higher level of denoising. Even with a denoiser at 0.7 or 0.85 Corona still preserves a good amount of details.
ok thanks for the info!
Additional info: from Corona 4 Beta, a much better bump map than the previous versions was introduced, as far as I see. Now, when I open old scenes and re-render, I see even the pores in wood surfaces even in total low res maps.
Such I always wanted before…
In my oppinion the new bump map became so good that I only rarely have to switch on displacement. Saves plenty of render time.
Well done Corona team !
youre getting a qick tip by hovering the mouse over the noise level in the vfb. If Im not wrong it´s proposing 5% with activated denoiser and 2% without denoising.
I think you will get awesome results on 3.6.
From my experience around 5% for stills (which is what’s recommended from the help doc) and for animation, for a good deal of scenes you can get away with just under 8% because movement will cover up a good deal of noise 
But at the end of the day, it depends on the scene.
This is really scene depended as the corona adaptive sampling is not that effective.
We had scenes with high DOF and used 2% with denoising and still got flickering in the background (even with low setting in GI/AA Balance).
That is definetly a thing what they have to improve. Other scenes where you have only one object with SSS and just a background colour the renderer sees 4% reached, but this is 4% noise level for the whole image. Your SSS will still look far from finished.
Long story short, I would recommend to test it. For stills test it in difficult areas of your render, for animations render a complete frame and make sure it fits your needs.
Cheers…