CCTV Lens Size Comparison: Focal Length and Field of View

A lens-size comparison is useful only when you also know the camera’s sensor format and the area you need to see. The same focal length can produce different coverage on different camera models. Use the manufacturer’s field-of-view figures instead of assuming that a millimeter value guarantees a particular viewing distance.

Wide view or narrow view?

For the same sensor format, a shorter focal length generally produces a wider view. A longer focal length generally produces a narrower view. A wide view provides more context, while a narrower view concentrates available pixels on a smaller area.

Neither is universally better. Define the target location and detail needed before choosing the lens.

Compare coverage with a simple example

For an ideal flat scene facing the camera, scene width is approximately 2 × distance × tan(horizontal field of view ÷ 2). At a distance of 10 meters, a 90-degree horizontal view covers about 20 meters across; a 60-degree view covers about 11.5 meters. These are geometry examples, not specifications for particular lenses.

Real installations also involve camera tilt, lens distortion, and targets at different distances. A site drawing and a manufacturer’s design tool help refine the estimate.

Why camera resolution matters too

Spreading a fixed number of pixels across a wider scene leaves fewer pixels on each subject. Increasing resolution can help, but focus, lighting, motion, and recording settings still determine usable detail. Check exported footage rather than judging only the live display.

Fixed, varifocal, and zoom choices

A fixed lens has one focal length. A varifocal lens allows adjustment within a specified range and may require refocusing. Motorized adjustment and autofocus depend on the model. Digital enlargement does not replace appropriate optical framing.

Lens selection checklist

  • Measure the target distance and required scene width.
  • Check horizontal and vertical field of view for the exact camera.
  • Account for mounting angle and obstructions.
  • Confirm focus and adjustment controls.
  • Test day/night footage of moving subjects at the target location.

Continue with fixed versus varifocal lenses, camera range, and the CCTV FAQ.