Yes, the cylinder in not primary visible. The blue is the camera's background-color.

There are no light's in the scene but I know from the hdr image, that the light doesn't evenly light the scene.

Yes a lot of things would help I recon BabyDuck.

Primarily I wonder how to make the hdr image darker. I can lower the lighting produced from that file, but I can't make it get real dark.

oh, if the floor was wider the diffuse-lighting would improve/be more realistic.