Understanding Fixed Focal Length Lenses
Fixed focal length lenses deliver reliable performance and high-quality imaging at a predetermined focal length. At Avantier, we produce custom lenses for robotics, machine vision, and numerous other applications.
A fixed focal length lens, also referred to as a prime lens, factory automation (FA) lens, or C-mount lens (when equipped with a C-mount system), is a multi-lens assembly with a constant focal length and a singular angular field of view, designed for seamless integration into imaging systems.
The focal length of a lens is defined as the distance from the lens to the point where the image is sharpest. Both magnification and angle of view are dependent on the focal length.
While a fixed focal length lens lacks zoom capability, it’s not restricted to imaging at a single distance. Most fixed focal length lenses have an optimal working distance and a minimum working distance, but no maximum. This allows them to image both distant and optimally placed objects, although distant objects will appear smaller. They are often designed with larger maximum apertures, enabling wide angles, expansive fields of view, and sharp, high-resolution images even in challenging lighting conditions.
Applications of Fixed Focal Length Lenses
Fixed focal length lenses, known for their reliability, are often incorporated into machine vision and robotic systems. They serve as an essential component in countless machine vision applications across research, medical imaging, surveillance, defense, industry, and conservation.
In photography, fixed focal length lenses, often called prime lenses, are widely used for camera lenses. While zoom lenses offer flexibility, prime lenses generally deliver superior image quality at their specific focal length, especially in long focal ranges. Their larger apertures also create a shallow depth of field, producing the aesthetically pleasing bokeh effect often seen in portrait photography.