Principal production crew of 60–90 personnel across 12–15 departments, responsible for filming all scenes with principal actors and dialogue sequences.
Technical Details
A standard main unit is divided into 12-15 departments: Direction (3-5 people), Camera (8-15 people), Lighting/Electric (6-12 people), Sound (3-4 people), Production Design (4-8 people), Costume (2-6 people), Makeup (2-8 people), Script/Continuity (1-2 people), and Production Management (3-6 people). The shooting ratio of the main unit averages 8:1 to 15:1, while second units often achieve 3:1 to 6:1. The main unit typically works with shooting days of 10-12 hours daily over 30-80 shooting days.
History & Development
In 1923, Irving Thalberg at MGM introduced the systematic separation between the main unit and second unit to reduce costs and increase efficiency. Cecil B. DeMille established the concept of department heads as a fixed main unit structure in 1926. In the 1950s, studios standardized the main unit size to 35-45 people for A-productions. Since the 1980s, the average main unit strength has grown to 60-90 people due to specialized departments such as VFX supervision and digital imaging.
Practical Application in Film
James Cameron led a 127-person main unit for "Titanic" (1997) over 160 shooting days, while the second unit concurrently comprised 40 additional people. Christopher Nolan deliberately works with reduced main units of 45-55 people for maximum control and intimacy on set. The main unit exclusively shoots scenes with principal actors, dialogue sequences, and all shots requiring specific directorial instructions. Establishing shots, stunts, and B-roll are handled by second units.
Comparison & Alternatives
Second units work in parallel to the main unit with 15-35 people under a second unit director, focusing on action sequences, landscape shots, and insert shots. Splinter units (5-15 people) shoot smaller scenes with supporting actors or pick-ups simultaneously. Since 2019, virtual production teams have supplemented traditional main units with LED volume specialists and real-time technicians. In streaming productions, "hybrid main units" of 25-40 people are increasingly emerging, flexibly switching between different episode blocks.