Show some of the other pics and maybe we might be able to figure it out. I just figured you might have had 40,000 megawatts flowing through the fixture, in which case you would probably be dead sitting so close, but it was a thought.
Does your light fixture have protrusions out in the area of the arms of the cross? Is there anything touching it in that way?
Maybe you are picking up another wavelength of electromagnetic radiation(light) that is effecting the film. Is it a digital camera?
Please take a picture with the fixture unplugged. It would show us more of what we are looking at.