Attach to the front of the light box some white fabric. You want some
really horrid, cheap polyester fabric in white, white, white. You
want polyester so there's no lint. Cut either a slit all the way up
the middle of the fabric, or just a smaller slit where the camera
will peak through.
Peak the camera through when you're ready to shoot. Now you'll have
the much smaller reflection of just the lens, not the whole camera.
This is what some professionals do.
Metalsmith, Certified PMC Instructor
Hard to Find Tools for Metal Clay