But I noticed one thing that seemed to me not acurate. I understand that the positions of the stars will be different when viewed from near a black hole, because the trajectory of their light was curved before reaching our virtual" eye. But I think the lens flares cannot be distorded so, because the processus that create them (diffraction on the camera objective) happens after the light passes near the black hole.

The black hole sucks light!

EDIT: Is it possible to change the position of the texture that makes the lens flare so it is always in front of objects, like how the ghosts are in this picture?