45.0

The lightbulb is placed on a glass surface (actually a TV table). That gives the reflection. There is a thin wire from the positive terminal (which is soldered - trying to be at least partly safe), and then a second wire at the back of the negative screw-thread which is just touching. The bulb is then connected via a standard light dimmer to the mains. The bulb is the only lighting in the room and I set it to about half brighness (it's a 40W bulb). The camera is on a tripod in A-mode and I exposed one shot of the lit bulb. I then turned off the bulb, put the camera to M mode setting a long exposure, changed the white balance, and now took a second shot with a torch shining just onto the screw thread. Then into Photoshop and blended the screw exposure with the lit bulb exposure and cloned out the wires (whilst also masking all the background down to black). Easy really! Except for the annoying vaporisation spots of the filament on the inside of the glass, which also needed spot cloning and dust & scratch filter work.