What defines a fixed lens in camera technology?

A fixed lens in camera technology is defined as having a fixed field of view and fixed focus. This means that the lens does not allow for zooming in or out, and the focus cannot be adjusted after it has been set. Fixed lenses are designed to have a specific angle of view, which remains constant, allowing the user to capture images within that predetermined scope.

These types of lenses are often used in scenarios where a specific composition is required, and they are preferred for their simplicity, reliability, and typically better optical quality compared to zoom lenses. Additionally, because they have fewer moving parts, fixed lenses often perform well in terms of speed and image quality, making them ideal for various photography and videography applications.

The other options mention features like adjustable focal lengths, autofocus systems, or variable fields of view, which do not apply to fixed lenses, since their primary characteristic is their unchanging nature in these respects.