Fixed focal length refers to a type of lens that does not allow for a change in the angle of view, meaning zooming in or out of a scene. Its opposite is a variable focal length lens, commonly referred to as a 'zoom' lens. With a fixed focal length lens, the focal length, which is given in millimeters and determines the width of the shot, is set to a single, unchangeable value. If the photographer wants to change the composition and how much of the scene the subject occupies, they must physically move closer to or further away from it. These lenses often have a simpler optical construction, which can lead to better image quality and higher light-gathering capability. Higher light-gathering capability means that more light passes through the lens, which makes it easier to photograph in low-light conditions and allows for better work with shallow depth of field, i.e., a blurred background.
