Lens Effect creates a blue firefly on just a single frame in an animation?

Hi guys,
could need some help here.

I have a pretty standard phoenixfd scene of a cruising boat.
Somehow, on just some random frames it creates this overblown blue firefly.

Interestingly, i’m rendering the animation with backburner on some slaves.
When i re-render the specific frame on my workstation. The firefly does not appear??

I already disabled hardware acceleration, because in the past i had some issues with it on some slaves.
But now, i’m pretty clueless where this pixel is coming from.
I also double checked everything to have no firefly pixel in the render itself.
It seems it’s only appearing in the lens effects pass?

Any clues? Drives me mad, because it just hapens very very randomly.
Thx in advance as always!


Hey man,

Sorry for the late reply - can you send over the scene eventually? Just a single cache will do the job I guess - which version of V-Ray are you using? How about if you lower the Max ray intensity in the V-Ray settings?

Hi Georgi!
Sorry for my late reply too, just busy with another thousand things…
I further worked on the scene and finally rendered it again with Vray 7 and et voila! it comes out flawless
cherry on top, it even reduced rendertimes at those hotspots quite a bit too.
You can see it here:

Looks super nice! Great job!

Thanks for sharing!