Society of Motion Picture Engineers : incorporation and by-laws (1919)

In making a fade, it is necessary that the exposure be diminished from the maximum to zero in a uniform diminuendo; or, in producing what is styled a fade-in, commenced at zero and with a uniform crescendo developed to the maximum normal exposure. Under good lighting conditions, the arc of movement from the normal exposure opening to that of a completed enclosed iris is extremely small ; so that a gradual decrease through this small arc is exceedingly difficult to accomplish in a uniform manner, especially as it is almost always complicated by the fact that the iris will not close completely and a complete fade-out can not be obtained. The general practice, where this complication arose, was to place the hand over the lens as soon as the iris was closed as far as it would go; thus ending it abruptly without accomplishing the final diminishing point. A dissolve, which is a fade-in superimposed upon a fade-out, would be farther complicated by the fact that, in many cases, a scene which dissolved into another might be taken under poor lighting conditions and be succeeded by one taken in strong light, so that the arc of movement used in producing the diminuendo in one might cover several times the angle of the arc of crescendo in the other. This leads to the conclusion that the only method of obtaining a uniform dissolve would be to gradually decrease the exposure time by gradually overlapping the sector blade of the shutter as it revolves; thereby gradually decreasing the exposure. A number of excellent mechanical devices for advancing the sector blade of the shutter have been perfected. They are of two classes ; the manually operated and the automatic. The manually operated is self-explanatory, as it is manipulated by the hand, while the camera is in operation. The automatic type is operated by the movement of the camera itself being brought into action at the required moment by throwing in a clutch driven from some part of the camera mechanism. With the manually operated dissolve, the fade may be of any desired length, whereas with the automatic, only a certain pre-determined length of fade may be produced. In the Shustek camera, the advancement of the sector blade is accomplished by a differential gear. In the Kronik Brothers' Camera two sector blades are advanced simultaneously from each side of the shutter opening by means of a pin passing through two curved slots in the sector blade, and a straight slot in the covering blade, this pin being actuated by a yoke which is moved in and out by a sliding sleeve on the shutter arbor. Only a very few of either of these types of cameras have been manufactured. The most common device for closing the sector blade is that of a spirally actuated sleeve upon the shutter spindle. In the Badgley shutter, which has been installed in dozens of Pathe and other makes of professional cameras, the sector blade is attached to a sleeve on the shutter arbor, which is hollow. A rod sliding in the hollow arbor carries a pin extending out through a straight slot in the arbor and engaging a spiral slot in the sleeve. By thrusting this pin-carrying member in or out of the shutter shaft, the relative position of the sector blade to the shutter opening is changed. A worm and gear train which may be thrown in or out of engagement with the camera mechanism by means of a clutch Si