I just want to create right caustic with any kind of water and anykind of lights ( not only simple sun ). As u can see, with a plane water, it create bad shape caustic, a have to reverse normal to have right look. And with single cube water, it completely cannot create right shape of caustic. This is not issue of camera. But thanks for the explosure tip.
I can just open it and press render to see the results -> just do whatever you want as long as u can create right shape of caustic, not matte water is a plane, or a volume object ( like cube, sphere ), no matte it's default normal surface or reverse normal surface.
You can see skot 2 ? THat's render with a reverse normal surface of a plane. And caustic is very fast to render.
And in skot 3 ? THat's render with a cube, caustic is wronq and very slow to render. Ie mean it must have an issue in there.
Another question, does rendertime is really different when I use a sphere geometry mesh light instead a Corona sphere light ?