Rendering sharp shadow on cycle rendering I would generate a clear shadow projected on a floor. I am wondering what is the essential node used to achieve this.

I am using these nodes 


and I get this image, I remark that the shadow is blurred (a lot of penumbra). I fix the focus at the floor and I try to change the Aperture (F/stop) to fit the depth of field.
reduce the size property of your lamp.