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Established since 1919, Robert Juliat is a French manufacturer of high quality lighting equipment for theatres, opera houses, events and architecture. World leader in followspot design, including the Award winning 1200W Super Korrigan,1800W Victor and the ground breaking 4000W HTI Lancelot, the product range also includes tungsten, discharge and LED zoom profiles, Fresnels, PCs and dimmers. All fixtures are designed for ergonomic perfection, optical and mechanical excellence and cover every need from the smallest theatre to the largest spectacular.
Female: A term applied to a connector that contains the holes or slots for receiving the pins, prongs, blades or tabs of a male connector. The female connector should always be attached to the line side of a circuit. Field Angle: The angle of the vertex of a cone-shaped beam where the perimeter of the base is defined by where the intensity is 10% of the maximum intensity. Field Diameter: The diameter of the base of a cone-shaped beam where the perimeter of the base is defined by where the intensity is 10% of the maximum intensity. Filament: The wire inside an incandescent lamp envelope that glows and emits light when heated, i.e., when electricity passes through it. Fill: To create the illumination needed to reduce shadows in an area or on a subject. Fill Light: Angled from the side opposite the key light, this light softens the shadows created by the key and evens out the lighting ratio. Filter: A term that refers to color media, diffusion material, light blocking or neutral density. Filter Frame: See Color Frame. Finger: A small, narrow, rectangular scrim, diffuser, reflector, or gobo, placed close to a light source, used for dimming, softening, bounce lighting, and casting shadows, respectively. Fingers are usually 2" to 6" in length, and 12" to 14" in width. FL: A lamp designation that means “flood.” Flag: (Filter, Gobo) An opaque panel, usually made of fabric, placed in the beam of a light source to block a portion of the beam or the whole beam. It can also hide lights in the dark recesses of a scene. They are usually square or slightly rectangular in shape, ranging from 10" to 48" in length, and 12" to 48" in width. Which term you use depends upon the device’s size and what part of the country you are in. Flash: A tube filled with xenon gas through which an electrical charge of high voltage is passed to create an electrical arc that emits a short, bright flash of light. Flash light is daylight balanced, usually measuring 5500° Kelvin. See Strobe. Flat Light: See Diffuse Light. All light is characterless, texture less and shallow shadowed when the source is close to the camera. Soft light is, by its nature, flatter than hard light, but even a soft source, above or to the subject’s side, is not flat. Flicker: The flashing of some light sources that cannot be visually detected because of the frequency of its output voltage, but can adversely affect the way motion picture film records light. Flicker-Free: A term used to describe electronic ballasts that electronically alter the electrical frequency that causes flicker. Flood: The position of a moveable lamp, lens or pair of lenses on a spotlight that produces the widest field angle. To direct a large amount of light on a relatively large area. Flood Light A light source consisting of a rectangular lamp and sometimes a single lens, used to direct a large amount of light on a relatively large area. Floppy Flag: A large flag that is designed to fold in half and function as a cutter or smaller flag. Fluorescence: The property of certain materials to absorb radiation of certain wavelengths, usually ultraviolet, and re-emit the radiation as light. Fluorescent Lights: Cool and daylight balanced, fluorescent lights have become very popular for photographic and video capture. Fluorescent lighting can be used in the form of screw-in bulbs and reflectors, or rectangular banks of lights. Foamcore: A polystyrene, Styrofoam material used as a substrate for some reflector boards, effective because of its light weight and ease of mounting via reflector forks. Focus: To aim and adjust a light source to give the beam its desired size (spot or flood), edge (soft or hard), field (even or peak) and shape (round, patterned or cut). Focus Lens: A movable lens in a multi-lens optical system that adjusts the focus of a light source. Follow Spot: A narrow-beam focusing instrument that is manually operated and is usually composed of a powerful light source, an iris, shutters, a color changer and other features. It is usually operated from an adjustable stand and is used to follow performer(s) on a stage with its beam, surrounding the performer(s) in a large pool of light. Foot-candle (fc): A non-metric unit of measurement for Illumination, i.e., 1 lumen per square foot. Framing Projector: A spotlight that has framing shutters or barn doors. Framing Shutters: Thin, movable, heat-resistant metal plates that are introduced into a beam such that a portion(s) of the beam is blocked off, i.e., framed; affecting the beam pattern, usually forming a sharp edge in the beam. They are used in various types of light sources, but extensively in ellipsoidal spotlights, usually four (top, bottom, right and left); follow spots, usually two (top and bottom), always situated internally, and usually at the aperture. Framing shutters generally can be independently adjusted, but those used in follow spots usually move simultaneously with a single control mechanism.French Flag: A small metal flag, usually used for shading. Fresnel: Short for Fresnel Spotlight. Fresnel Lens: Named for its inventor, French physicist Augustin J. Fresnel, and developed around 1800 for lighthouses, this is a flat lens consisting of concentric rings on one side that are segments of the spherical portion of a Plano-convex lens. The other side is flat, i.e., Plano. It controls light in the same manner as a Plano-convex lens, which converges light into a beam. Many light sources employing this type of lens have a stippled pattern on the flat side of the lens to diffuse to smooth out the beam. Fresnel Spotlight: A spotlight employing a single Fresnel lens that produces a soft-edged beam, usually provided with a spherical reflector and a means to adjust the focus from spot to flood. F/Stop: A rating often applied to scrims used in the film and video industries on their ability to dim light. This rating is directly related to a camera’s ability to allow for the admittance of light. Full Scrim: A metal scrim whose screen occupies the complete frame. Fuse: An electrical device designed to stop the flow of electricity automatically when a predetermined over current tries to pass through it. This is meant to prevent further damage or fire from overheating. Fused Quartz: A relatively pure, high-temperature glass used to manufacture lamp envelopes. It has a melting point of approximately 1650° C. Gaffer: The lighting technician who is in charge of the electrical aspects of a set or production. Gaffer Grip: A large, spring-loaded clamp with serrated or rubbercushioned jaws. It usually has a stud or studs for the attachment of luminaries and grip equipment. Gaffer’s Pole: See Operating Pole. Gag: An apparatus composed of two grip heads attached to each other via a common bolt. Gel (Gelatin, Media): As used with photographic lights, a strong, flexible, fade-resistant material, used to change the color, amount or quality of light. A colored filter placed in front of a lighting fixture. Color is an important element in adult learning Gobo: A logo or image etched out of metal that allows it to be projected onto a screen, wall, banner or other solid surface. Often used for brand reinforcement during events. Video mapping can be used to produce a similar by higher-end effect. Guide Number: Guide numbers are used as a rating system to gauge the power or range of flash. The guide number equals the distance x f/stop. For example, say your flash has a guide number of 80’. At ISO 100, to determine the proper exposure for a subject 20 feet away, multiply 20 by X number (in this case 4) to get 80 (the guide number). Setting the aperture to f/4 (80 = 20 × 4) will render a proper exposure (at ISO 100). Hair Light: Light source aimed at a subject’s hair to create separation from the background and add sparkle and highlights. Halation: The distortion that appears around the edge of a sharply focused beam pattern. This effect can be reduced with the aid of a donut. Half Scrim: A metal scrim whose screen occupies one half of its frame so that the straight edge of the screen is located across the diameter of the frame. It is used to cut light output. Halogen: The name for a family of gases, used in lamps, to maintain proper color temperature. Hard Edge: A beam pattern edge that is very clear and distinguishable, i.e., one without a fuzzy or blurry perimeter. Hard Light: Illumination that has a hard edge and produces sharply defined shadows. Often this light is very intense, but generally less flattering than soft light. A light source that provides such illumination. Head: A general term for a Fresnel spotlight. The part of a follow spot that contains the light source, i.e., not the stand, ballast or interconnect cable. The part of a metal halide light source that contains the lamp, i.e., not the ballast or interconnect cable. The part of an ellipsoidal spotlight that contains the reflector, i.e., not the lens barrel or the cap. Short for Grip Head or Ball Head. Hertz: A unit of measurement for the Frequency of alternating current, i.e., one cycle per second. Highboy (Hiboy): A heavy-duty stand designed to hold light sources or heavy grip equipment. The stand is equipped with wheels and tall risers, and usually a 1 and 1/8" receiver and a grip head. High Key: A lighting style in which the majority of the scene is highly illuminated, usually enhanced by bright costumes and sets. A low ratio of key plus fill light lowers the contrast, helping to obtain this effect. Hollywood Box: A piece of power distribution equipment used in the film and video industries, composed of a metal housing, a means for connecting an electrical supply and female flush-mount connectors or bus bars that can be electrically connected with bus bar lugs, for the purpose of supplying electricity to light sources. Some are also provided with over current protection. Hot Lights: Common term for continuous light sources, especially tungsten or halogen lights that run hot. Hot Restrike: A term applied to an igniter that can hot-start an arc lamp. Hot Spot: The spot of light with the highest intensity, ideally located at or near the center of a beam that has been focused for a peak field. Hot Start: A term used to describe the ignition of a heated arc lamp, i.e. a lamp that has just been electrified. HMI: Abbreviation for Hydrargyrum (Greek for Mercury) Medium-Arc Lodides. This is a commonly used type of metal halide lamp manufactured by Osram-Sylvania Corp. The term Osram HMI is trademarked. Hz: Abbreviation for Hertz. Illumination: Generally, a term for light or lighting. In photometry, the amount of light, i.e., luminous flux per unit area incident on a surface, in foot-candles or lux. Incandescent: A term used to describe a lamp, or a light source that utilizes such a lamp, that employs the incandescence of a filament as its light source. The filament is housed in a vacuum; enough electricity is passed through the filament that it glows. Such a lamp was first developed by Thomas Edison (United States) and Joseph Swan (Great Britain), independently, in 1879. Indirect Lighting: Illumination that falls on an area or subject by reflection, e.g. bounce lighting. Inky: A small Fresnel spotlight with a 1.5" to 3" lens diameter, usually 100250 watts. Intensity (Light Output): The “strength” of the incident light source, independent of the subject’s reflectivity.