When it comes to selecting the right CCTV lens for peripheral and corridor coverage, two popular options are fixed focal length (FFL) lenses with a 2.8mm focal length and varifocal lenses. In this blog post, we will delve into the technical aspects of both types of lenses to help you make an informed decision for your surveillance needs.

Fixed Focal Length (FFL) 2.8mm Lenses

Fixed focal length lenses offer a consistent field of view throughout their entire zoom range. The most common fixed focal length lens used in CCTV applications is the 2.8mm, which provides a wide angle view ideal for monitoring wider areas such as hallways or large rooms.

• Field of View: A 2.8mm FFL lens typically offers an approximate field of view of 90 degrees (diagonal) and 53 degrees (horizontal). This is suitable for covering spaces up to approximately 20 meters in width.

  

• Resolution: The fixed focal length of a 2.8mm lens ensures consistent image quality across the entire frame, making it ideal for situations where you need to maintain high resolution throughout your field of view.

Varifocal Lenses

Varifocal lenses offer adjustable zoom capabilities, allowing users to fine-tune their field of view without physically moving the camera or lens. This flexibility makes varifocal lenses particularly useful in environments with changing distances or areas that require frequent monitoring adjustments.

• Zoom Range: Varifocal lenses typically provide a wider zoom range compared to fixed focal length lenses. For example, a varifocal lens may offer a 4x optical zoom, allowing the user to dynamically adjust the field of view from approximately 90 degrees (wide) down to 22 degrees (telephoto).

  

• Adaptability: The ability to adjust the zoom range in real-time makes varifocal lenses highly versatile. This is especially beneficial for monitoring dynamic environments or when the surveillance requirements change over time.

Choosing Between FFL 2.8mm and Varifocal Lenses

When selecting a CCTV lens, consider the following factors:

1. Field of View: Determine the area you need to monitor and choose a lens that provides an appropriate field of view without sacrificing image quality or resolution.

2. Zoom Requirements: If your surveillance setup requires frequent adjustments to the monitored area, varifocal lenses may be more suitable due to their adjustable zoom capabilities.

3. Resolution Needs: Fixed focal length lenses offer consistent resolution across the entire field of view, which is ideal for high-resolution surveillance applications.

4. Budget and Availability: Both fixed focal length 2.8mm and varifocal lenses are widely available at competitive prices, so cost should not be a significant factor in your decision.

In conclusion, the choice between a fixed focal length 2.8mm lens and a varifocal lens ultimately depends on your specific surveillance requirements. Fixed focal length lenses offer consistent image quality and resolution, while varifocal lenses provide greater flexibility for adjusting the field of view as needed. By carefully considering your needs and the factors outlined above, you can make an informed decision that best suits your CCTV security setup.

📊 CCTV System Design Reference Infographic