When I render two identical objects at different sizes, the smaller one is a lot brighter. The only way I can get them to look the same is to change the light settings. (If I draw the object at half size, and scale the light intensity by half, it looks right.) Is there any reason for this, or am I missing something?

Make sure you''re normalizing your surface normals. To do that, divide your axial components by the vector''s magnitude.

  float reciprocalDistance = 1.0f / sqrtf(square(vector.x)+square(vector.y)+square(vector.z))vector.x *= reciprocalDistance;vector.y *= reciprocalDistance;vector.z *= reciprocalDistance;