Spheres

I don't really have much practice at shading realistically namely due to my eyesight problems so my friend advised shading some spheres and here they are. This is a first attempt, grapite 4H to 6-8B and I shaded in the background so it didn't look so white. This really isn't about perspective so I'm aware the shadows look odd on the spheres, just imagine they're all on a unique plane.