Archive
Tag "Useful"
Original Auto Focus (Aug, 1971)

And it only weighs 7lbs!

The Lens That Focuses Itself
Ever shoot an out-of-focus picture? Then you’ll be interested in the newest lens from Nikon. It focuses as automatically as your eye, and just as fast. You can just point and shoot at fast-moving subjects from athletes to zebras without giving focus a thought. As long as you keep your subject within the sensing circle in the center of your viewfinder, you’ll get sharp pictures. Any drawbacks? Sure. The lens is k big (11 inches long), heavy (it weighs six pounds including the batteries that power the autofocus mechanism), slow (f/4.5), and you won’t be able to buy one until next year.—A. J Hand

How does it work? Like this:

Light reflected from the subject passes through the first group of lens elements and is split by a ring mirror. Some of the light passes through the lens to the film plane. The rest is reflected down to the autofocus mechanism where a condensing lens forms an aerial image. The position of this image will vary according to distance of the subject. A contrast-sensing set of four photocells inside the autofocus system moves up and down the shaft of focused light. Every time the photocells pass through the point of focus (also the point of highest contrast) they send a pulse to the logic circuit. At each up-and-down cycle of the four cells, a clock pulse is fed to the logic circuit as well. A third pulse indicating the current focus of the lens also is transmitted to the circuit. The circuit takes the three pulse signals and converts them to a time signal. The time signal corresponds to the distance between the sharpest image position and the current focus position. An analog circuit and power amplifier actuate a servo motor that shifts the movable lens elements to bring the lens into focus. All this takes place several times a second—scanning, computing, and refocusing.

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“Tiny” Walking Radio (Feb, 1937)

Devise Tiny Walking Radio

A NOVEL radio transmitter is used by representatives of the Columbia Broadcasting System to conduct roving interviews. The device consists of an antenna and radio frequency oscillator mounted in a cane, a microphone on a wrist strap, batteries in a money belt, and an audio amplifier and modulator in a binocular case. Working range is one mile.

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Deaf Hear Through Head Bone (Mar, 1933)

Deaf Hear Through Head Bone

AN INVENTION for hearing by the conduction of sound through the bony structure of the head instead of through the outer ear was successfully demonstrated recently before the engineering society in New York.

How the contraption is worn is illustrated in the photo below. The heart of the instrument is a special transmitter worn on the clothing which intercepts the words spoken to the deaf or partially deaf person. This transmitter is connected to the oscillator which presses against the bony part of the cranium when the listening is to be done. Ordinarily, however, the oscillator is worn like a necklace around the throat as illustrated in the photo below.

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Seedless Watermelon Produced by Student (Apr, 1939)

Seedless Watermelon Produced by Student

Watermelons without seeds are produced by chemical treatment of watermelon blossoms, in a process perfected by Cheong Yin Wong, graduate student at Michigan State College, East Lansing. In the photograph, Wong holds a piece of seedless melon in his right hand.

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Dictating Machines to Use Magnetic Tape (Oct, 1934)

Dictating Machines to Use Magnetic Tape

With the development of the steel tape method of sound recording, present day dictaphones may soon become obsolete. In demonstrations at the Century of Progress sound was stored in the magnetic ribbon for only a few seconds, but engineers believe it possible to construct a simplified dictating machine set along similar lines.

With the use of large rolls of the steel tape, there would be no need to change records as frequently as in the present apparatus. Court proceedings could be stored indefinitely.

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Living Shadow Dances on Giant Electric Sign (Mar, 1941)

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Living Shadow Dances on Giant Electric Sign

PIROUETTING in front of a bank of photo-electric cells, Dixie Dunbar, New York dancer, recently cast a living silhouette on the world’s largest animated electric sign above the Great White Way. Her shadow, thrown on the electric eyes, blacked out lights in corresponding areas of the sign. In regular operation, animated-cartoon silhouettes are projected on the cells from a movie film.

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