Framing projectors use optical lenses and physical shutters to shape light. Four adjustable blades cut the beam. The result is a sharp, distinct polygon of light matching the dimensions of a canvas or plinth. Ambient light levels drop. The artwork appears self-illuminated.

Optical Mechanics

Standard spot fixtures produce a soft-edged circle. Framing fixtures incorporate a condenser lens system. Light passes through a primary lens, hits the shutter plane, and exits through an objective lens. Focus adjustments harden or soften the edge. Hard focus creates exact cuts. Soft focus allows minor blending on textured surfaces.

  • Objective Lens: Determines beam angle. Typical ranges fall between 15° and 45°.
  • Shutters: Four stainless steel blades. Independent manipulation allows trapezoidal corrections.
  • Gobo Slot: Accepts templates for complex shapes. Used for sculpture illumination.

Diodes and Color

Color rendering dictates performance. Chips must achieve a minimum CRI of 98. R9 values (saturated red) must exceed 90 to render skin tones and warm pigments accurately. Two-step MacAdam ellipse binning ensures color consistency across multiple fixtures. Color temperatures remain fixed at 3000K or 4000K. Tunable white systems introduce complexity and reduce peak optical efficiency.

Thermal Management

High output LED chips generate heat. Condenser optics trap it. Passive cooling is mandatory. Extruded aluminum heat sinks dissipate thermal loads. Active cooling fans introduce acoustic noise. Museums require NC-25 or lower ambient noise ratings. Fans fail. Heat sinks do not.

Pros and Cons

Pros: Unmatched contrast ratios. Directs focus. Eliminates glare for viewers. Protects surrounding materials from unnecessary lux exposure.

Cons: High capital cost. Complex focusing process. Requires re-focusing if the artwork moves 10mm. Lower total lumen output compared to standard spots due to optical glass loss.

Component Specification Range Museum Requirement
CRI 80 - 99 ≥ 98
Beam Angle 10° - 60° 15° - 45° adjustable
Dimming Protocol Phase, DALI, Casambi DALI (0.1% depth)
Cooling Active / Passive Passive only

Installation demands a lift, patience, and direct access to the final curatorial layout. Framing before artwork installation wastes time. Shutters lock. Lenses lock. Pan and tilt lock. System remains rigid until the next exhibition.