Flickering when using BF+LC & BF+BF

[stevesideas]

If I am getting flickering in both the above methods can it only be a mesh/material error ?

[Morne]

or AA too low or maybe a light causing issues with a material

I had one not too long ago where the sun was giving specular flicker on all my cars. It was a tight deadline so instead of changing each car's material, I made a second sun specifically for the cars that excluded everything else but included the cars. From the 1st sun I excluded the cars.

If you saved out the elements maybe check the animation of each to see where the flicker is coming from

[stevesideas]

I've had issues with the sun and some hi intensity sparkles on parts of the car in the scene but these are shadows and dark areas on a particular mesh. I have them down to a minimum but I'm just wondering what is causing them. I'll upload an animation at some point to show you what I mean.

[Morne]

Sometimes I think there's something wrong with the vray sun/sky models. One day it works great and then the next you get these fireflies all over the place. Did an animation recently and the skylights on the roofs had major flicker and jumping all over the place in the specular element. Had to override the glossy reflection of that glass to 0.7 to get rid of it

[Deflaminis]

I ran into this recently and for me it was (weirdly) turning OFF clamp in color mapping that fixed it. Man I wish I saved that scene...

[Zdravko.Keremidchiev]

I've had issues with the sun and some hi intensity sparkles on parts of the car in the scene but these are shadows and dark areas on a particular mesh. I have them down to a minimum but I'm just wondering what is causing them. I'll upload an animation at some point to show you what I mean.

The speckles that you get usually appears when having very high-reflective material and strong light source. This is so, because some of the surfaces are reflection the light directly in the camera, which creates very bright sports. When the AA try to smooth them out - it is unable to properly approximate between the normal and the over bright areas. In real life photography those areas will be covered by lens effects.
So to workaround the issue first make sure that you don't use any sharpening filters. Also you can enable "Sub-pixel mapping" and "Clamp output" options which will clamp the brightness of those over bright areas to the value that can be properly anti-aliased (please note that this will reduce the dynamic of the output).
Another way to fix that will be either to correct the material/lights settings or you can use Morne approach:

I had one not too long ago where the sun was giving specular flicker on all my cars. It was a tight deadline so instead of changing each car's material, I made a second sun specifically for the cars that excluded everything else but included the cars. From the 1st sun I excluded the cars.

EDIT:
oh, now I saw that you actually "turning OFF clamp" to fix the issue. That is strange in deed, it will be nice if you could find this scene.