Here's another mirror trick for converting a small room into a TV studio.  Suppose that my old college radio station WOBC-FM turned into WOBC-TV and wanted to install cameras and studio lighting in the underused "conference room."  In 1970, I dreamed up a way to do it. The textbook illustration at the upper left shows that performers need to be lit from three directions.  The backlight, highlighting the hair and shoulders, should be aimed down at 45° or so.  It's at least 5 feet behind and 5 feet above the 6-foot performer, which puts it 11 feet above the floor.  But ordinary rooms, like the WOBC conference room, usually have only 8-foot ceilings. As shown on the upper right, I've lined the wall with periaktoi, triangular prisms which can be rotated for quick backdrop changes.  One face might be black, another smooth gray, the third a textured fabric.  A foot in front of them, a little "ground row" hides red, green, and blue lights that shine up from the floor to illuminate the backdrop.  And also on the floor are the backlights! (TEXT CONTINUED BELOW) The trick, as shown at the bottom:  a mirror on the ceiling.  The backlight shines up from the base of the wall, bounces off the ceiling, and reflects down to hit the performer at the proper angle.  (Should the camera aim too high, as shown here, the mirrored ceiling reflects the backdrop to minimize the error.) Of course, there's a simpler solution:  put the backlight at the top of the wall, but don't allow the performers to stand up!  If they're always seated behind a desk, their heads will be about four feet below the ceiling, and the backlight can be made to work.  That's how it's done on the news set at the Pittsburgh studio of Fox Sports Net.