General Guidelines
The Camera
- Don't move the camera between shots. Not even the tiniest little bit. If you do, the two images will not be aligned which will affect the final image.
- Lock the exposure. Do not let the camera auto-expose or the exposure on the foreground object will change when the lightness of the background is changed.
The Object
- Don't move the object.
- Be careful when the background reflects in the object(s) - the reflections become transparent areas in the final image.
- A good rule of thumb is to keep the background as far away from the object as possible. It makes it much easier by reducing reflections and lighting variations on the foreground object(s).
The Background
- Make sure the background doesn't show up as 0 or 255 in the captured images. A good light background is around 200 and a good dark background is around 50. You don't have to struggle to get a pure white or pure black background.
The Lighting
- If changing the color of the background with lighting, don't let any of the background lighting spill over onto the object. It will affect the foreground object's exposure.