Black Squares in DOF

[Joelaff]

I am trying to render some fine water droplets (lots of little particles and particles from RealFlow meshed with Frost) with really shallow DOF. I have bokkeh turned on. I am getting some black squares in the render (not always precisely the size of a bucket). I am using Adaptive DMC. Increasing the min subdivs to 5 seems to have mainly gotten rid of them. I assume this has something to do with the details being too fine to be picked up with fewer samples.

I tried increasing min samples in settings, but this didn't seem to have much of an effect.

Is this normal? Anyone else seen this, or have a better (faster rendering) way to fix it. I saw the same issue when using shademaps as well...

Thanks.

[tashko.zashev]

Hi,

Could you post an example render image?
Do you have overlapping faces?
Did you try to increase the "secondary rays bias" parameter?