Jittering rendering results on a neon sign

[einkaufZHH57]

Hey folks,

I've a strange render issue in my c4d-scene. I built a neon sign with a circular mesh that is used as light source.

The left side of the image renders pretty well, but on the right side, the neon pipes look very jittery and I have no clue why. The geometry is build like on the left side and looks perfectly smooth:

The result looks like that:

Does anyone has an idea, what the problem might be?

Thanks for your help!

[lee_griggs]

Are they both mesh_lights? What do they look like as just geometry with emission/ bloom?