For a production of “Singin’ in the Rain” I designed a ‘rain unit’ that was essentially a large, moveable fountain dressed as a city street. To emphasize the running water, we used 3D texture on the walls instead of painted flats. Poor lighting would have flattened the set (and performers).

Above: production photo.
Next: “worklight” photo.

Although a painted drop is usually lit either evenly bright or dim, three-dimensional sets (columns, fences, stucco) will hardly be noticed without supportive lighting.

“The Messenger” production photo. Lighting by Deirdre Adams.

“Jesus Christ Superstar” production photo. Lighting by Kade Mendelowitz.

In arena or thrust theatres, costumes are often heavily relied upon to help display a sense of time period and style. For these settings, large scenic pieces can easily destroy audience sightlines. The closer the audience gets to the actors, the more detail that is needed in the costume pieces.

Color variation in costumes can also be hidden in dark scenes.

During a production of “Tuma”, a Native Alaskan performance piece, the costumer told the lighting designer that she could find 12 matching black body suits for skeleton characters. Luckily, because the scene used blacklight to highlight bones painted onto the body suits, the audience could not see the difference between the black costumes, thereby adding more unity to the group of skeletons.

Changes in time and locale are often achieved through lighting.

“The Laramie Project” production photos. Lighting by Adam Gillette.

In a unit set, it may be up to the lighting designer to determine whether a scene is taking place the next day, a few hours later, etc.

Next two photos: from a production of "Stop Kiss" - Lighting & Scenery by Kade Mendelowitz.

There may be one set piece for a Shakespearean production that indicates “the forest”. However, it is up to the lighting designer to show whether this piece is the same forest or a different part from the previous scene in “A Midsummer Night's Dream”.

Sound may also affect changes in lighting.

Primarily in dance and concerts, light changes may be motivated by music: tempo or beat changes in addition to choreography.

Lighting often supports the mood of a production. In musicals, dance pieces and concerts, the mood is often dictated by the music.