1. What is Security Camera Focal Length?

Focal length is a fundamental specification of camera lenses that determines the field of view and magnification of the image. In security cameras, selecting the right focal length is crucial for proper coverage and identification capabilities.

2. How Does the Calculator Work?

The calculator uses the focal length formula:

Where:

• \( Distance \) — Distance from camera to subject (meters)
• \( Sensor Size \) — Camera sensor size (millimeters)
• \( Field of View \) — Desired coverage width (meters)

Explanation: This formula calculates the optimal focal length needed to achieve a specific field of view at a given distance with a particular camera sensor size.

3. Importance of Focal Length Calculation

Details: Proper focal length selection ensures your security camera covers the desired area effectively, provides adequate detail for identification, and minimizes wasted coverage areas.

4. Using the Calculator

Tips: Enter the distance from camera to subject in meters, the camera sensor size in millimeters, and the desired field of view width in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical sensor size for security cameras?
A: Common sensor sizes range from 1/4" (approx. 3.6mm) to 1/2.7" (approx. 6.4mm), with 1/3" (approx. 4.8mm) being very common in modern security cameras.

Q2: How does focal length affect the field of view?
A: Longer focal lengths provide narrower fields of view with more magnification, while shorter focal lengths provide wider fields of view with less magnification.

Q3: What's the difference between fixed focal length and varifocal lenses?
A: Fixed focal length lenses have a single, unchanging focal length, while varifocal lenses allow adjustment of the focal length within a specified range.

Q4: How does sensor size impact the effective focal length?
A: Smaller sensors effectively magnify the image, making the focal length appear longer than it actually is (crop factor).

Q5: Should I consider vertical field of view as well?
A: Yes, for complete coverage assessment. The calculator provides horizontal field of view, but vertical field of view is typically about 75% of the horizontal measurement for standard aspect ratios.