Select Camera and select Object Constraint.

Add Object Constraint > Child Of

Select the target.

Object > Track > Track to Constraint
Now, the camera follows the object like real cameraman.

Add path.

Camera > Add Object Constraint > Follow Path

Select the target.

Set the camera location of x,y,z as 0,0,0.
And, press Animate Path.

Scene Properties > select Camera
You can change the main camera by "command + B" on timeline.

Focus length = The bigger, the nearer.
F-Stop = The bigger, the clearer. The smaller, the more blurry.
Focus Distance = The smaller it is, the clearer the near object is.