When choosing stage lights, the consideration of the focusing performance of the lamps

When choosing stage lights, the consideration of the focusing performance of the lamps

The focusing performance of stage lights directly affects the clarity, coverage and luminous effect of the light beam, and is a key factor determining the visual effect of the stage. The following analysis is conducted from four dimensions: the core indicators of focusing performance, the focusing characteristics of different types of lamps, the adaptability to application scenarios, and the methods of selection and testing, to help users scientifically evaluate the focusing capabilities of lamps.

First, focus on the core indicators of performance

Spot uniformity

Definition: The difference in brightness between the center and the edge of the light spot. High-quality lighting fixtures should achieve a smooth transition from the center to the edge, avoiding "overly bright center and blurred edges" or "light spot discontinuity".

Uniform light spots can ensure consistent lighting effects for stage characters or props, avoiding visual fragmentation caused by differences in brightness.

Case: In theatrical performances, uniform light spots can clearly present the facial expressions of actors, while blurred light spots at the edges will weaken the presentation of details.

Adjustable range of beam Angle

Definition: The divergence Angle of the light beam in a lamp is typically classified into narrow beam (<10°), medium beam (10°-30°), and wide beam (>30°).

Meaning: Wide beams are suitable for large-scale lighting (such as sky screen backgrounds), while narrow beams are suitable for precise lighting (such as solo dancers).

Case: In a concert, a narrow beam of 5°-10° should be used for the close-up of the lead singer, while a medium beam of 20°-30° should be used for the band area.

Zoom ability

Definition: The ability of a lamp to adjust the beam Angle through mechanical or optical structures is divided into fixed focal length and variable focal length (such as continuously adjustable from 15° to 50°).

The zoom lamps can adapt to different stage distances and scene requirements, reducing the number of lamps and installation costs.

Case: In variable stages (such as those shared by theaters and concert halls), zoom lamps can cover different performance areas by adjusting the beam Angle.

Edge sharpness

Definition: The clarity of the edge of the light spot, which is divided into hard edges (such as cutting lamps) and soft edges (such as wall-washing lamps).

Meaning: Hard-edge light spots are suitable for outlining the contours of objects, while soft-edge light spots are suitable for creating an atmosphere.

Case: In a dance performance, hard-edge light spots can highlight the actors' body movements, while soft-edge light spots are suitable for rendering the stage background.

Dispersion control

Definition: The phenomenon of color separation caused by refraction or reflection during the propagation of a light beam.

Meaning: Dispersion can reduce the purity of the light spot, especially in colored light beams (such as RGB lamps), which requires special control.

Case: In project-type lamps, dispersion can cause the edges of text or patterns to become blurred. To reduce dispersion, optical coating or lens design is required.

Second, the focusing characteristics of different types of lamps

Spotlight

Focusing method: The light beam is converged through a lens group or a reflection bowl, resulting in high uniformity of the light spot and sharp edges.

Applicable scenarios: Scenarios that require precise lighting (such as the dialogue area of a drama, close-ups of a soloist).

Limitations: The zoom range is limited, usually a fixed focal length or a small range of zoom (such as 10°-20°).

Profile Light

Focusing method: By combining the lens group and the adjustable screen (Gobo), hard-edge light spots and pattern projections can be achieved.

Applicable scenarios: Scenarios where light spot cutting or pattern projection is required (such as architectural outline outlining, LOGO projection).

Limitations: The uniformity of the light spot is affected by the screen, and shadows may appear at the edges.

Wall Wash Light

Focusing method: Large-area uniform illumination is achieved through a soft light lens or diffuser, and the edge of the light spot is softened.

Applicable scenarios: Scenarios requiring soft background light (such as stage background coloring, audience area ambient lighting).

Limitations: The beam Angle is fixed and precise lighting cannot be achieved.

Moving Head lamp

Focusing method: Built-in zoom lens group, supporting wide-range beam Angle adjustment (such as 5°-50°).

Applicable scenarios: Scenarios that require dynamic light effects (such as concerts and music festivals).

Limitations: The uniformity of the light spot may decrease during zooming, and optical design optimization is required.

LED PAR Light

Focusing method: The beam Angle is fixed through a reflector cup or lens, and the uniformity of the light spot is medium.

Applicable scenarios: Low-cost and easy-to-install lighting is required (such as for small-scale performances and temporary stages).

Limitations: The beam Angle is fixed, and the lens or lamp needs to be replaced when zooming.

Third, focus on the compatibility of performance with stage scenes

Theatrical stage

Requirements: Precise lighting, high uniformity, and hard-edge light spots.

Compatible lighting fixtures: spotlights, imaging lights.

Case: In a play, imaging lights are used to cut the light spots, highlighting the facial expressions of the actors while preventing the light from overflowing into the background.

Concert

Requirements: Dynamic light effect, wide-range zoom, dispersion control.

Compatible lighting fixtures: moving head light, zoom spotlight.

Case: When taking a close-up of a singer, use the narrow beam (5°-10°) of the moving head light to focus on the face; When the band is playing, switch to a wide beam (30°-50°) to cover the entire area.

Dance performance

Requirements: Soft edge light spot, uniform dyeing, dynamic beam.

Compatible lighting fixtures: Wall-washing lights, LED flat lights.

Case: In ballet, wall-washing lights are used to evenly color the stage background, while the dynamic beam of moving head lights is used to enhance the sense of rhythm.

Immersive performance

Requirements: Miniaturization, hidden installation, and precise light spot.

Compatible lighting fixtures: micro LED lighting fixtures, floor lamps.

Case: In escape room performances, micro-LED lamps are embedded in props or walls, guiding the audience's line of sight through precise light spots.

Fourth, selection and testing methods

Laboratory test

Spot uniformity: Use an illuminance meter to measure the illuminance values at the center and edge of the spot, and calculate the uniformity (edge illuminance/center illuminance ×100%).

Beam Angle verification: Measure the beam Angle of the lamp at different focal lengths through a laser rangefinder and a spot projector.

Dispersion test: Observe whether a rainbow-colored halo appears at the edge in a white beam, or analyze the degree of dispersion through a spectrometer.

On-site simulation

Distance test: Observe the size of the light spot and the edge sharpness at a simulated stage distance (such as 10 meters, 20 meters).

Dynamic zoom: Test the stability of the light spot during the zooming process of the lamp to avoid the "breathing effect" (the size of the light spot fluctuates with zooming).

Masking cutting: Perform masking cutting on the imaging lamp to check if there are any shadows or light leaks at the edges.

Long-term stability

Thermal attenuation test: After continuously running the lamp for 2 hours, measure the uniformity of the light spot and the proportion of brightness decline.

Mechanical durability: Repeatedly adjust the zoom and focusing mechanisms to check for any lag or looseness.

User feedback

Case reference: Consult the lighting technicians of similar stages about their actual usage experience, with a focus on the stability of the light spot, the smoothness of zooming, and maintenance costs.

Scene adaptation: Request the supplier to provide real shooting effect pictures or videos of the lamps in different scenarios to evaluate whether their focusing performance meets the requirements.

Fifth, Summary and suggestions

Core principle: The focusing performance should be highly compatible with the stage scene, taking into account the uniformity of the light spot, the adjustable range of the beam Angle, the zoom ability and the edge sharpness.

Selection method:

Clarify the type of stage and lighting requirements, and select the appropriate type of lighting fixtures (such as spotlights, wall-washing lights).

The focusing performance and long-term stability of the lamps were verified through laboratory tests and on-site simulations.

Refer to user feedback and cases to evaluate the performance of the lamps in practical applications.

Optimization strategy:

In scenarios where precise lighting is required, imaging lights or high-precision spotlights should be given priority.

In scenarios with high demands for dynamic lighting effects, choose moving head lights that support a wide range of zooming.

Complex lighting effects can be achieved through the combination of multiple lamps (such as spotlights + wall-washing lights), reducing the limitations of a single lamp.