The motion picture projectionist (Oct 1927-Sept 1928)

34 The Motion Picture Projectionist August, 1928 Projection Nomenclature Aperture — The opening through which the light passes between its source and the screen. The film passes vertically at the aperture. Cement — A chemical solvent used to join two pieces of film together. Ether is one of its active constituents. Film cement evaporates quickly, therefore should be kept in tightly corked containers. Exchange — A central depository from which film may be bought, rented, or borrowed. Film Mender — A clamp-like device used to facilitate the splicing of film. Footage — Refers to length of a roll of film. Frame (noun) — Refers to a single photograph in the roll of film. There are 16 frames to every foot of standard film. Frame (verb) — The operation of correctly aligning the picture on the screen. ■"Framing" is accomplished by moving a lever or some other similar device. Frame Line— -The line that divides the top of one image from the bottom of the other. This line is observed when picture is in misframe on the screen. Geneva Movement — A form of intermittent movement first used in Geneva, Switzerland ; hence the name. It is the form of intermittent movement that is most used. Intermittent — The device that moves the film normally at 16 frames per second. Leader — Blank or opaque pieces of film at beginning of the reel placed immediately ahead of the title. It is placed there to facilitate threading the projector and to protect the first few feet of the title. Legend — Titles and Subtitles — Words of explanation descriptive of various scenes in the film. Loop — Slack places left in the film, one immediately above the aperture and another immediately after the intermittent sprocket. Mazda Equipment — The incandescent lighting unit used in professional projectors. All portable and semi-portable machines are equipped with incandescent lamps. Carbon arcs are used in professional projectors. Where it is necessary to project pictures at great distances carbon arcs are always used. Mazda equipment is coming to be used more, and more as time goes on, for shorter projection distances. Misframe — Caused by an improperly spliced film, or incorrect threading of projector. Operator — The individual who manipulates the projection apparatus. Perforations — Sometimes called sprocket holes — on both edges of the film. In standard film there are 64 perforations on each edge, per foot. Positive Print — Film exposed to light behind a negative. The positive is used in the projector. /T\ HE accompanying article on projection nomenclature was published in the first issue of THE MOTION PICTURE PROJECTIONIST and is again published in deference to several thousand of our present subscribers who did not receive the October number, as well as to supply a demand for it by a steadily increasing number of our correspondents. Additions or corrections to this listing will be welcome. Patch — See Splice. Projector — An apparatus provided with the necessary devices for showing pictures on a screen. Projectionist — A skilled operator of motion picture apparatus — an expert. Rain Streak — Tiny scarlet in the emulsion that soon accumulate dirt. Caused by dirty projector or "pulling down" film. Reel — The spool upon which film is wound. Sometimes the term reel refers to the film itself as well as the spool upon which it is wound. Rewind (noun) — A device used to change film from one spool to another either for the purpose of inspection or to make it ready for the next exhibition. Remind (verb) — To change film from one reel to another. Screen — A surface upon which the picture is projected. Safety Shutter — Sometimes called fire shutter. The safety shutter is located between the film and the light source and opens or closes at the aperture automatically when the machine starts or stops. Shutter (Revolving) — The device used to intercept the light during the time the film is in motion at the aperture. The shutter also serves to minimize the flicker on the screen by increasing the oscillations of light and shade to such a frequency that the eye cannot detect them. Twoblade and three-blade shutters are in general use. Splice — A place where two pieces of film have been joined by use of film cement. Such a union is sometimes called a patch. Sprocket Wheels — The revolving toothed wheels that engage the perforations and thereby move the film through the projector. There are usually three such sprockets ; one found immediately after the film leaves the reel ; the intermittent sprocket which jerks the film sixteen times per foot between the loops and the lower or take-up sprocket from which the film passes directly into the take-up reel. Take-Up — The device used to wind the film as it passes through the projector. Tension Shoes — Found on either side of the aperture. They hold the film gently yet firmly against the aperture. Throw — Distance from screen to the projector. Trailer — Blank or opaque pieces of film at the end of the reel. This is placed there as a protection against damage to the valuable film in the reel. Travel Ghost — The peculiar hazy appearance often seen in a motion picture. It is produced by the improper setting of the revolving shutter. Lens Definitions Axis, Principal — A straight line drawn through the centers of curvature of a lens or in case of a lens having one curved and one plane face, it is a line through the center of curvature of the one face, and perpendicular to, and through the center of the other face. Center of Curvature — Since a lens is made up of the intersection of two spheres, or of one sphere and one plane, the center of curvature of the lens may be considered as the center of the sphere of which its face is a part. Condensers — The lens combination which deflects the divergent rays of the luminant into the objective. Focus, Equivalent — The equivalent focus of a plurality of lenses in combination is the focal length of a simple thin lens which will, under all conditions, form an image having the same magnification as will the given lens combination. Focal Length — The distance from the center of the lens to the principal focus is called the focal length. Focus, Principal — The principal focus of a lens is the point on the principal axis at which rays parallel to the principal axis come to a focus. Lens — A lens may be defined as a piece of glass,, or other transparent substance, having two curved surfaces or one curved and one plane surface. Objective — The picture-forming member (lens) of the optical system. This is sometimes called the projection lens. Projection Lens — Properly called projection objective. Projection Distance — -The distance between the objective and the screen of a stereopticon or motion picture projector. Working Distance — The distance from the slide or film in a system to the nearest lens of the objective.