Simmod Variable ND Filter (82mm, 1.3 to 6-Stop)

Controlling exposure in cinema and digital imaging often requires maintaining a fixed shutter speed and aperture while adapting to changing lighting conditions.

A variable neutral density filter allows exposure reduction without altering camera settings or image characteristics associated with aperture and shutter adjustments.

The Simmod Variable ND Filter (82mm) is a rotating variable neutral density filter designed to provide adjustable exposure reduction from 1.3 to 6 stops while maintaining controlled color transmission and operational repeatability.

Filter Format

• Rear thread size: 82mm
• Front thread size: 86mm
• Variable ND range:
  • 0.4 to 1.8 optical density
  • Approximately 1.3 to 6 stops of exposure reduction

The larger front diameter is designed to reduce vignetting when used on wider focal lengths.

Optical Function

The filter is designed to:

• Reduce exposure without changing aperture or shutter speed
• Maintain shallow depth of field in bright environments
• Preserve motion blur consistency for cinema frame rates
• Allow continuous exposure adjustment during changing lighting conditions

The variable density system operates through rotating polarized optical elements.

Self-Locking Variable ND System

The filter incorporates a dual-ring structure consisting of:

• Rotating density adjustment ring
• Independent locking ring

This allows:

• Precise density positioning
• Repeatable exposure settings
• Prevention of accidental ND adjustment during operation

A side lever is integrated into the rotating ring for controlled adjustment during handheld or rig-mounted operation.

Optical Construction

• German Schott optical glass
• 16-layer Multi-Resistance Coating (MRC16)
• Anti-reflective optical treatment
• IR-controlled transmission characteristics

The coating system is designed to:

• Reduce reflections and ghosting
• Minimize flare artifacts
• Improve transmission consistency
• Resist water, oil, dust, and surface contamination

The optical design is intended to maintain neutral color transmission throughout the ND range.

Mechanical Construction

• Precision-machined aluminum frame
• Rotating outer density ring
• Independent locking collar
• Matte black internal finish

The structure is designed to maintain smooth rotational control while minimizing unintended movement during operation.

Mechanical Performance

• Continuous variable exposure adjustment
• Hard-stop rotation limits
• Designed to reduce over-rotation associated with X-pattern artifacts
• Front 86mm threading supports:
  • Lens caps
  • Matte box clamp-ons
  • Additional threaded accessories

Image Characteristics

The filter is designed to:

• Maintain controlled color neutrality
• Preserve contrast consistency
• Reduce highlight clipping during bright exterior shooting
• Maintain cinematic shutter speed operation in daylight conditions

The effect varies depending on:

• Lens focal length
• Sensor polarization sensitivity
• Lighting direction
• ND density setting

Vignetting may occur on ultra-wide full-frame lenses approximately between 14mm and 19mm due to lens field curvature and filter geometry.

System Behavior

• Passive optical filter system
• No electronic components
• Compatible with:
  • Spherical lenses
  • Anamorphic lenses
  • DSLR, mirrorless, and cinema camera systems

The filter does not alter internal lens mechanics or calibration.

Included Components

• Variable ND Filter
• Protective felt storage case

Notes

• Requires compatible 82mm front filter thread or step ring
• Variable ND filters may exhibit polarization interaction depending on scene lighting and lens design
• Proper matte box clearance should be verified when stacking filters or accessories