I'm not Jay, but I think I can answer this. The cameras appear to have had a flat aluminum finish, not white paint.
The two numbers you really want are absorptance (α), the fraction of incoming visible and near-IR light (from the sun) that is absorbed and converted into heat, and emittance (ε), the efficiency of the surface in radiating thermally in the far IR. The ratio of the two, among other things, control the equlibrium temperature in sunlight.
This explains apparent paradoxes like polished metals getting very hot in the sun. Although they have very low absorptance, their emittances are even lower so what little heat they absorb, they hold. If you want to make a solar heat collector, you still want the blackest possible surface.
When you want to isolate a surface thermally from the environment, as you usually do on the moon because of the large changes between shade and sun, you generally want low values for both α and ε -- hence the metallic finishes on the cameras.
