What are fixed focal length lenses?

Fixed focal length lenses, commonly also referred to as factory automation (FA) lenses, C-Mount lenses, or prime lenses, are imaging lens assemblies designed with a singular angular field of view and constant focal length. Fixed focal length lenses typically have a minimum working distance, an optimal working distance, and no maximum working distance. These lenses are available with a variety of mounts, anti-reflection (AR) coating, resolution options, and much more. For more information about fixed focal length lenses and how they differ from other imaging lenses including telecentric lenses and M12 lenses, read about Types of Machine Vision Lenses, Basic Lens Selection, and Advanced Lens Selection.