Deep Focus

Technical Details

Depth of Field Formula (DOF):

DoF = (2 × N × c × s²) / (f² - N × c × s)

N = Aperture value (e.g., 11 at f/11)
c = Circle of Confusion (~0.03mm for full-frame cinema)
s = Subject distance in meters
f = Focal length in mm

Practical Examples:

50mm lens, f/11, focus at 3m:

• Near Focus Limit: 1.8m
• Far Focus Limit: infinity
• Total Depth of Field: ~2m range in focus

35mm lens, f/8, focus at 2m:

• Near Focus Limit: 1.2m
• Far Focus Limit: infinity
• Total Depth of Field: ~1m range in focus

28mm lens, f/5.6, focus at 1.5m:

• Near Focus Limit: 0.9m
• Far Focus Limit: infinity
• Total Depth of Field: ~0.7m range in focus

Hyperfocal Distance:
The focus point at which the depth of field extends from the acceptable near limit to infinity.

Calculation: HFD = (f² / (N × c)) + f

Example: 24mm, f/8, full frame (c=0.03mm):
HFD = (24² / (8 × 0.03)) + 24 = 240cm + 24cm ≈ 2.64m

Focusing at this distance = everything from ~1.3m to infinity sharp!

Split-Diopter (Split-Field Diopter):
Optical element that affects only HALF of the lens:

• Enables two different planes of focus in one shot
• Typical: Foreground sharp + background sharp (otherwise impossible)
• Famous through Brian De Palma ("Blow Out", 1981, "Body Double", 1984)
• Cost: $3,000-$8,000 per diopter
• Problems: Visible line in the image if not perfectly centered

Digital Focus Tools:

Preston FI+Z System:

• Motorized focus follow
• Accuracy: ±1mm over a 20-meter distance
• Real-time remote control (wireless)
• Cost: ~€8,000-€15,000 daily

Arri WCU-4 (Wireless Control Unit):

• Integration with ARRI cameras
• Precision focus motors with 0.5mm resolution
• Repeatability: Identical focus pulls across multiple takes
• Cost: ~€6,000-€12,000 daily

Cmotion easyRig Follow Focus:

• Mechanical precision focus control
• Integration with 3D camera motion
• More affordable alternative to Preston
• Cost: ~€4,000-€8,000 daily

Lighting Requirements for Deep Focus:

• f/8: Minimum 2,000-3,000 lux on set
• f/11: Minimum 4,000-6,000 lux
• f/16: Minimum 8,000-12,000 lux
• Outdoor natural light with reflectors/diffusion

History & Development

Gregg Toland & "Citizen Kane" (1941):
Revolutionized deep-focus cinematography with:

• Mitchell Standard Camera (industry standard at the time)
• Cooke Anamorphic Lenses (28mm wide-angle instead of standard 35-40mm)
• Massive Lighting: 10,000+ watt lamps (Kliegl, Mole Richardson)
• Aperture f/8-f/11 for extreme depth of field
• Technique: Focus from 60cm (desk) to infinity (window)
• Effect: Simultaneous action in 3-4 planes of the image without cuts

Toland's innovation was not the invention of deep focus, but its perfection as a dramatic tool. He combined optical depth of field with lighting architecture and blocking for storytelling.

Orson Welles (1941-1962):
Welles understood deep focus as narrative depth, not just a technical gimmick:

• "Citizen Kane" (1941): Simultaneous family dramas in different planes of the image
• "The Magnificent Ambersons" (1942): Architectural depth of field for social hierarchy
• "The Lady from Shanghai" (1947): Deep focus for psychological confusion

Stanley Kubrick (1962-1999):
Perfected extreme deep focus with special optics:

• "Lolita" (1962): Kubrick's first deep-focus phase
• "Dr. Strangelove" (1964): Satirical depth of field in the war room scene
• "2001: A Space Odyssey" (1968): Zeiss f/0.7 lenses (NASA technology) for revolutionary spaceship depth of field
• "Barry Lyndon" (1975): Candlelight deep focus with f/0.7 for 18th-century authenticity
• "The Shining" (1980): Steadicam deep focus through 45-meter corridors

Digital Era (2000-present):

Preston Systems (since 1998):

• Electronic follow-focus revolution
• Enables precise focus pulls without manual "focus turning"
• Becomes standard on all major productions

Digital Intermediate (since 2000):

• Post-production can perform software-based depth of field simulation
• Criticism: Non-optical bokeh character is noticeably different
• Rarely used, as real optics are more convincing

LED/Virtual Production (since 2015):

• In-camera deep focus in virtual environments (Unreal Engine)
• Real-time rendering allows flexible depth of field changes
• Example: "The Mandalorian" (2019) uses LED walls with deep focus

Practical Use in Film

Orson Welles' "Citizen Kane" (1941) – The Iconic Deep Focus Scene:
The desk scene: Kane sits sharply in the foreground at his desk, while his mother and the banker negotiate sharply in the mid-ground through a window:

• Focal length: 28mm (wide-angle)
• Aperture: f/8-f/11
• Focus point: Kane's face (approx. 1.5m)
• Focus range: 60cm (desk) to infinity (window)
• Psychological effect: Three actions in the same picture space = psychological complexity

Stanley Kubrick's "Barry Lyndon" (1975) – Candlelight Deep Focus:
Uses Zeiss f/0.7 lenses with candlelight for painterly deep focus:

• Aperture: f/0.7-f/1.4 (despite low aperture!) with special lighting
• Focal length: 28-35mm
• Psychological effect: Intimate closeness with simultaneous context

Stanley Kubrick's "The Shining" (1980) – Steadicam Deep Focus:
The legendary hotel corridor sequences with Steadicam and deep focus:

• Steadicam speed: ~1cm per second (deliberately slow)
• Focal length: 18-24mm
• Aperture: f/5.6-f/8 for continuous sharpness
• Focus trickery: Split-screen focus with manual follow
• Psychological effect: Infinite architectural depth symbolizes a psychological labyrinth

Roger Deakins' "Sicario" (2015) – Selective Deep Focus:
Border scenes with partial deep focus:

• Foreground (agents): f/5.6 sharp
• Mid-ground (border): f/5.6 sharp (due to wide-angle)
• Background (armed groups): f/5.6 sharp
• Psychological effect: No escape possibility – everything is present

Andrzej Wajda's "Ashes and Diamonds" (1958) – Black & White Deep Focus:
Polish classic with classic deep focus:

• Black and white enhances depth (no color distraction)
• Deep focus as a means to visualize political conflicts
• Psychological effect: Classic melancholy

Paul Thomas Anderson's "There Will Be Blood" (2007) – Minimal Deep Focus:
DP Robert Elswit selectively uses shallow focus instead of deep focus:

• Statement: Rejection of Welles' deep focus ideal
• Focus: Only on Daniel Day-Lewis (extreme isolation)
• Psychological effect: Modern psychological fragmentation instead of narrative depth

Comparison & Alternatives

Deep Focus vs. Shallow Focus:

• Deep Focus: Everything sharp, documentary, democratic image
• Shallow Focus: Selectively sharp, cinematic, psychological isolation
• Combined: Modern "hybrid" approach with targeted shallow focus in a deep-focus setup

Rack Focus vs. Deep Focus:

• Deep Focus: Remains sharp over long takes
• Rack Focus: Focus shifts during the shot
• Technical: Deep Focus = static, Rack Focus = dynamic

Pull Focus vs. Deep Focus:

• Pull Focus: Manual focus shift between points
• Deep Focus: No focus shift needed (everything sharp)
• Practice: Pull focus is often elegant but can be distracting

Split-Diopter vs. Deep Focus:

• Deep Focus: Everything sharp in one optical plane
• Split-Diopter: Two separate planes of focus in one image
• Use: Split-diopter for impossible combinations (e.g., close-up sharp + background sharp)

Digital Depth of Field Simulation (Post-Production) vs. Optical Deep Focus:

• Optical: Real bokeh character, appears more natural
• Digital: Can be adjusted later, but costs time/money
• Criticism: Digital DoF simulation is often too perfect, looks artificial
• Trend: Digital solution is increasingly accepted for low-budget productions