ok so here’s the scene:
there are:
camera, a bottle (absorbtion), a big plane, a cyclinder with 1 open hole (glossy 0 roughness), and a circle (in the cylinder, emission 3000)
and then this is the preview
Hard scene for ray tracer, there are must be lot of noise by definition, expect 4000+ samples to clear noise a bit. Every bounce even on perfect mirror like surface will be measured, imagine how many interreflections inside that tube for rays not parallel to main cylinder axe. Do you trying to get caustics on table? if not then use real spot lamp.
Hi, Cycles is not really suitable to render such a light situation especially with caustics.
The render get worse first and than better after a huge amount of samples.
You need an engine with bidirectional pathtracing like Luxrender, Yafaray for example.
Or you switch “No Caustics” on.
Cheers, mib.
