A snoot is a cone or tube shaped light modifier that fits over the front of a studio flash head, continuous light source, or spotlight to restrict and concentrate the light output into a narrow, controlled beam that illuminates only a small, defined area of the subject or scene. By channelling the light through a progressively narrowing passage before it leaves the modifier, the snoot prevents light from spreading broadly across the scene as it would from an unmodified flash head or lamp, directing it instead in a tight, focused cone whose diameter and spread are determined by the length and aperture of the snoot.
The snoot takes its name from the informal English word for nose - a reference to its elongated, projecting shape that protrudes from the front of the light source like a nose from a face. It is typically manufactured from metal, rigid plastic, or flexible rubberised fabric in a conical or cylindrical form, with a mounting collar at the wide rear end that attaches to the light source's accessory fitting, and a circular opening at the narrow front end through which the concentrated beam of light emerges. The ratio of the length of the snoot to the diameter of its front aperture determines the angle of spread of the emerging light beam - a longer snoot with a smaller front aperture produces a narrower, more concentrated beam, while a shorter snoot with a larger aperture produces a broader, less concentrated cone of light.
The snoot is used in studio and location photography to produce a distinctive and highly controlled lighting effect characterised by a pool of light on a small, defined area surrounded by a relatively dark, unlit background. This quality of lighting is particularly useful for accent lighting and highlighting specific features of a subject - illuminating a model's hair to separate it from the background, drawing attention to a specific product feature in commercial photography, creating a dramatic spotlight effect on a performer's face in theatrical or entertainment photography, or adding a precisely placed catchlight or highlight to a specific area of a still life composition. The hard edged, concentrated beam of a snoot creates strong contrast between the lit and unlit areas, lending a dramatic, graphic quality to the lighting that is quite different from the broad, soft, and wrapping illumination of larger modifiers such as softboxes and umbrellas.
The edge quality of the light pool produced by a snoot can be varied by adjusting the distance between the snoot and the subject - moving the snoot closer produces a harder, more sharply defined edge to the light pool, while moving it further away produces a softer, more gradually feathered edge - and by the use of honeycomb grids inserted into the front opening of the snoot, which further control the directionality and spread of the emerging beam. Coloured gels can also be fitted over the front aperture of a snoot to colour the concentrated beam for creative effect, producing a tightly controlled spot of coloured light that can add dramatic accent colours to a background or subject without contaminating the broader ambient lighting of the scene.