I'm learning the basics and while modeling a simple volcano using a point lamp for the magma I keep getting unnatural sharp shadows, even when disabling ray shadow. I don't think the problem is in the mesh (you can find the .blend file in the comments). Here are some examples:
In this case I put the lamp outside the crater. If I disable Ray Shadow here it gets better.
Now placing the lamp inside the crater. Even when I disable Ray Shadow I keep getting those sharp transitions.