In dim light, each ommatidium cannot function independently. The iris and retinal sheaths of the ommatidium shrink in dim light. As a result, the crystalline angle becomes uncovered. Light rays from the object enter the rhabdome through the cornea. In this case light rays from the cornea of one ommatidium in addition to light rays from neighboring ommatidiums enter the same rhabdome. As a result a blurred reflection is formed. This is called superposition reflection.