Disable reflexion in a cycle material

Hi every one!

I’m trying to make a realistic black hole with cycle…

The problem is that as soon as I do something transparent with refraction (either with glass or principle) I get a slight reflexion on my surface. Even if I have no specular or metalicity… If I use roughness not only will it keep a blury reflexion (wich my black hole will not be black), but my refraction get blured too. Anybody has an idea?

Thanks in advance!

If you want refraction only, use a refraction BSDF.

Hi,

I have been struggling for true transparency as well. Trying different options, I luckily found one that works. Probably it is not the best, but it does the job and you can adjust the transparency from 0 to 1. The file I use is just an empty file (alpha).

As mentioned already, use pure refraction instead. Glass and principled simulate a glass like material, which is a fresnel mix of refraction and reflection - hence there will always be reflections (for IOR>1). Don’t use refraction roughness though, and tweak, possibly map the IOR to say how much light is bent where. I don’t need any black holes in my regular work, so I’ve never made one in Blender, but I’m pretty sure tutorials exists.