// focal blur camera
camera
{
  location  < 0, 1, -5 >    // position
  look_at   < 0, 0, 0 >     // view
  aperture 1.0              // [0...N] larger is narrower depth of field (blurrier)
  blur_samples 10           // number of rays per pixel for sampling
  focal_point <0,1,2>       // point that is in focus <x,y,z>
  confidence 0.95           // [0...1] when to move on while sampling (smaller is less accurate)
  variance 1/200            // [0...1] how precise to calculate (smaller is more accurate)
}
