Rack Focus / Pull Focus

Technical Details

Lens Requirements for Rack Focus:

Rack Focus requires specific optical characteristics:

1. Linear Focus Characteristic:

• Focus throw of at least 180° to 360° on the focus ring
• Consistent focus speed across the entire range
• Cinema lenses have optimized focus curves

1. Focus Markings:

• Measurement system in feet (Imperial: 1', 2', 3', 6', 10', 25', ∞)
• Metric: 0.3m, 0.5m, 1m, 2m, 5m, 10m, 25m, ∞
• Precise intermediate values for millimeter-accurate focus placement

1. Standard Focus Hubs:

• Standard Hub (Arri/Panavision): Diameter ~52mm
• Mikada Hub: Diameter ~42mm
• Fujinon Hub: Proprietary (usually not compatible)

Follow Focus Systems:

Mechanical Follow Focus (older style):

• Gear drive via thumbwheel
• Accuracy: ±2-3cm
• Cost-effective ($800-$2,000)
• Fully manually controlled

Preston FI+Z System:

• Wireless electronic focus control
• Accuracy: ±2mm via laser distance measurement
• Focus Memory: Up to 16 programmable focus points
• Speed Ramps: 0.1°/s (ultra-slow) to 360°/s (fast)
• Cost: €12,000-€20,000 daily

Arri cforce motors:

• Motor-driven focus axis
• Integration with Arri LDS (Lens Data System)
• Automatic calibration for different lenses
• More cost-effective than Preston (€8,000-€12,000 daily)

Easyrig Follow Focus (mechanical-precision):

• Lever-based, no motor
• Speed varies depending on lever size
• Affordable (€2,000-€4,000 for equipment purchase)
• Popularity in Independent Films

Focus Measurements for Rack Focus:

1. Laser Rangefinder:

• Accuracy: ±5cm over 20+ meters
• Popular models: Bosch GLM, Leica DISTO
• Cost: €200-€600

1. Tape Measures / Fiber Tape:

• Classic method: Steel tape from focus point
• Accuracy: ±2-3cm (manual dependent)
• Very cost-effective (€10-€30)

1. CineTape (Digital Rangefinder for Film):

• Integration with Preston/Arri systems
• Automatic focus point storage
• Cost: €200-€400 (rental equipment)

Rack Focus Speed Parameters:

Typical rack focus speeds:

• Ultra-slow (0.1-0.5°/s): 5-10 second transitions (meditative effect)
• Slow (1-2°/s): 2-5 second transitions (standard emotional)
• Medium (5-10°/s): 0.5-2 second transitions (fast narrative)
• Fast (30-50°/s): under 0.5 seconds (action-dynamic)
• Ultra-fast (100-360°/s): Snap focus with no visible transition (automated)

Rack Focus Formulas:

Focus speed in °/s required for desired transition duration:

Focus Speed (°/s) = Total Focus Throw (°) / Transition Duration (s)

Example:
- Focus Throw: 90° (from 3m to 1m distance)
- Transition Duration: 2 seconds
- Required Speed: 90° / 2s = 45°/s

History & Development

Early Rack Focus (1940s):
Rack focus only became possible with fast cinema lenses (f/1.4 and faster) that produced sufficiently shallow depth of field:

Gregg Toland "Citizen Kane" (1941):
Toland first systematically perfected rack focus:

• Second desk scene: Focus shifts from Kane's shadow to Kane himself
• Technically: Manual focus pull with precise marking
• Psychological effect: Attention is guided with the focus

Brian De Palma (1970s-1980s):
Made rack focus his signature tool:

• "Sisters" (1972): Rack focus as psychological manipulation
• "Blow Out" (1981): Legendary rack focus between microphone and assassin
• "Body Double" (1984): Split-screen rack focus combined with split diopter
• Style: Visual tension through focus shift rather than cutting

1970s Technical Innovation:
Arri and Panavision developed specialized follow focus systems:

• Gear drive with thumbwheel control
• Counterbalance for long lenses
• Marking systems for precise reproducibility

1990s-2000s Electronic Revolution:

• Preston Systems electronic follow focus (1998+)
• Wireless control allows focus puller to be behind the camera
• Digital focus memory for complex transitions

Modern Era (2010-present):

• Arri LDS (Lens Data System) automatically integrates lens data
• Wireless integration with monitor displays
• AI-based focus prediction (experimental)
• Virtual Production: Real-time LED wall focus adjustment

Practical Use in Film

Brian De Palma "Blow Out" (1981) – The Iconic Rack Focus Scene:
During a recording session, a rack focus shifts attention:

• Focus begins on the microphone (symbol of recording)
• Rack focus to the assassin in the background (threat)
• Focus follows the assassin while the main character becomes blurred
• Psychological effect: Visual tension mapping without cutting
• Technically: Manual focus pull with precise calibration

Mike Nichols "The Graduate" (1967) – Seduction Rack Focus:
Seduction scene between Benjamin and Mrs. Robinson:

• Focus starts on Benjamin (curious, confused)
• Slow rack focus to Mrs. Robinson (seducer)
• Focus stays on Mrs. Robinson as she approaches
• Psychological effect: Attention "falls" for the seducer
• Technically: Slow rack focus over 4+ seconds

David Fincher "The Social Network" (2010) – Fast Rack Focus:
Dialogue scenes with rapid rack focus between speakers:

• Fast rack focus (0.5-1 second) between two actor positions
• Simulates psychological shifts in attention
• No cut: Continuous camera position
• Psychological effect: Tension and dialogue dynamics
• Technically: Preston FI+Z system for speed

Paul Thomas Anderson "The Master" (2012) – Psychological Rack Focus:
Confrontation scenes with psychological rack focus:

• Focus on Freddie Quell's eyes (emotional vulnerability)
• Rack focus to Lancaster Dodd (manipulation/control)
• Focus transitions mirror psychological power dynamics
• Psychological effect: The focus itself is a dramatic statement
• Technically: Multi-point rack focus (5+ focus points per scene)

Denis Villeneuve "Sicario" (2015) – Asymmetrical Rack Focus:
Interrogation scenes with power mapping through rack focus:

• Focus starts on FBI agent Kate (position of power)
• Rack focus to villain Del Toro (assumption of control)
• Focus remains on Del Toro = visual power shift
• Repetition throughout the scene manifests psychological inversion
• Technically: Arri WCU-4 for precise speed ramps

Pedro Almodóvar "All About My Mother" (1999) – Melodramatic Rack Focus:
Emotional scenes with rack focus between characters:

• Often used in theater scenes (DP: Jose Luis Alcaine)
• Rack focus between audience reaction and stage action
• Psychological effect: Guiding audience empathy through focus
• Technically: Classic manual focus pull

Sonya Dyson "Nope" (2022) – Sci-Fi Rack Focus:
UFO encounter scenes with nervous rack focus:

• Fast, nervous rack focus between the sky (UFO position) and actors
• Creates a visual state of unease
• Psychological effect: Focus instability = psychological distress
• Technically: Rapid-fire rack focus (0.2-0.3 second transitions)

Comparison & Alternatives

Rack Focus vs. Follow Focus:

Rack Focus:

• Focus shifts BETWEEN static objects
• No camera or actor movement necessary
• Psychological tool

Follow Focus:

• Focus TRACKS a moving object (e.g., an actor running)
• Camera and actor move
• Technical tool for focus control

Rack Focus vs. Split Diopter:

Rack Focus:

• Dynamic (temporal)
• Two focus positions sequentially
• Focus is presented at different times

Split Diopter:

• Static (spatial)
• Two focus positions simultaneously
• Both are sharp at the same time (each in half of the frame)

Practical difference: Rack focus requires two different focus positions, split diopter allows BOTH simultaneously

Rack Focus vs. Cutting:

• Rack Focus: Attention shifts WITHOUT cutting (elegant, subtle)
• Cutting: Abrupt change between cameras (direct, dynamic)

Modern cinema: Rack focus is used less than it used to be (3% vs. 15% in classic Hollywood) as fast cutting feels more modern

Digital Focus Transition (Post-Production) vs. Optical Rack Focus:

Optical (In-Camera):

• True optical bokeh during transitions
• Creative tool under the control of the focus puller
• Very visible, less subtle

Digital (Post-Production):

• Synthetic depth-of-field manipulation
• Post-hoc control, less real-time control during shooting
• Often shows artifacts, looks artificial
• Affordable low-budget alternative

Combination Techniques:

Dolly Zoom + Rack Focus:

• Perspective distortion (dolly zoom) combined with focus shift
• Creates psychological confusion
• Rarely used (too complex)

Camera Movement + Rack Focus:

• Steadicam moves while rack focus occurs
• Creates complex spatial confusion
• Technically very difficult (requires 2+ focus pullers)