Depth pass

Does anyone know how to render a Z-pass that can be used in something like Shake or After Effects in Blender 2.53?
Thank you.

To render a z-pass all you need to do is press Render.

To actually see it and use it you need to go into the compositing.

In Map Value you have to set the Size lower (like in example). ColorRamp is for more precise control.

Thank you I see.