What Is a Varifocal Lens?

A varifocal lens offers the ability to adjust the focal length, thereby changing the field of view (FOV) and level of detail captured by a surveillance camera. This adaptability makes it possible to "zoom in" or "zoom out" on the observed scene without physically relocating the camera.

Types of Varifocal Lenses:

  1. Manual Adjustment: Requires physical adjustment of the lens.
  2. Motorized Lenses: Allow remote adjustments during live monitoring.

Applications and Benefits of Varifocal Lenses

Manual Varifocal Lenses

  • Best for Fixed Installations: Once set, the focal length remains unchanged.
  • Use Cases:
    • Fine-tuning the viewing area during installation.
    • Adjusting the lens after relocating the camera.

Specifications:

  • Typical adjustment range: 2.8–12mm, offering flexible coverage.
  • At a 10-meter distance:
    • FOV can range from 17m to 4m.

Motorized Varifocal Lenses

  • Ideal for Active Monitoring: Adjust the focus remotely in real time.
  • Integrated Features: Often paired with pan-tilt-zoom (PTZ) capabilities.
  • Control Methods:
    • Joystick controllers.
    • Software interfaces on DVRs or video servers.
  • Professional Use Cases: Large venues like stadiums, shopping malls, and critical infrastructure.

Advantages of Varifocal Lenses

  1. Flexibility in Adjustments:

    • Manual lenses provide control during installation.
    • Motorized lenses allow dynamic adjustments based on security needs.
  2. Enhanced Detail and Coverage:

    • Zoom in to focus on specific areas or widen the view to monitor larger zones.
  3. Cost-Effectiveness for Versatile Surveillance:

    • Ideal for settings with uncertain or evolving monitoring needs.

Key Considerations for Choosing Varifocal Lenses

  • Focal Range: Opt for a range suitable for the surveillance area (e.g., 2.8–12mm for typical applications).
  • Build Quality: Higher-quality optics yield sharper images and better durability.
  • Use Case: Manual lenses suit static installations; motorized lenses excel in dynamic environments.
  • Price: Motorized lenses are more expensive and often paired with professional-grade cameras.

Varifocal lenses bring versatility and precision to surveillance systems, making them indispensable for both residential and commercial security setups.