I’m exploring lighting with cycles and can’t quite work out what’s happening here. A cube on a plane with a sun lamp gives sharp black shadow in BI, but almost no shadow at all in Cycles even with shadows checked in the Integrator and the world color set to black so as not to introduce ambient lighting. I’m wondering how one could ever represent a city scene this way.
Must have had some odd settings. Doesn’t look light I can get parallel light rays though.
Hi!
Set size property to 0 for a sun lamp.
Thanks!! 
I was moving it very far away and setting the strength to max (1000000)
Cycles uses physically accurate lights, so size is taken into account. Also, I would recommend NOT using Blender lamps, as most of them have no real world counterpart, and a few aren’t even supported. Create mesh lights instead, and they will be treated as area lamps, as are nearly all light sources in the real world.
If you are going for real sun light, a small value like 0.01 or .003 will work better. after all the sun disk in the sky is effectively an area light.