Need help with DoF

Hello everybody. I was experimenting with Depth of Field in Cycles and I am having some troubles. I want the DoF to change gradually throughout the animation so I set up my scene, created an empty and have that be the focus point. Over a period of 80 frames, the empty moves around the scene. To test it out, I rendered frame 1. After it rendered, I went to the Compositer and set up the Defocus node. After 15 minutes, I am totally stumped and cannot figure out how to make the Defocus node focus on an object in the distance. Do the DoF in the camera settings really effect the compositer? Because I am convinced it doesn’t.

In cycles you dont use the defocus node. In the camera properties panel, in the depth of field settings. Set the Empty as the focus point and then set the radius amount. Start small like .050 and work from there. That setting can be keyframed also, so you can change the amount throughout the animation.

Oh alright. That makes sense. I just have one more question, what does the Blades option do?

Alright. I got it now. Thanks!