making a light shadow sharp

[Anonymous]

Hi, 

I've created a wall 40 cm wide with a lot of reveal in it(40 cm wide) in order to put light inside the building and have it work as a sharp shadow on an adjacent building. All i'm getting is soft shadow and not sharp one.

How do i fix this?

In other places the light does sharp shadows (mullions of windows)

[barthbradley]

Can you post a picture showing what you mean?  

[barthbradley]

[ToanDN]

Is this sharp?

[barthbradley]

This shadow is so sharp, it can cut through a soda can like a Ginsu,