When was the world's first zoom lens used for photography?

The development of zoom lens has a long history. In fact, when photography technology was just born, it had not really entered the practical stage. It was in 1834 that the British mathematician Peter Barlow put forward the idea of adding a negative lens to the eyepiece of a telescopic telescope. "In this way, the lengthened lens can be adjusted so that its magnification can be changed at any ratio, even without leaving the lens from the eye or the line of sight from the observed object." This is the original intention of designing zoom lens.

However, Barlow's idea was not put into practice until more than fifty years later. 1890 and 189 1 year, an Englishman, a Frenchman and two Germans invented very similar telephoto lenses respectively.

This kind of lens was welcomed by photographers as soon as it appeared, but it is still far from perfect in technology. First of all, during use, whenever the magnification (focal length) of the lens changes, the camera must be refocused; Moreover, with the increase of focal length, the effective aperture value of the lens will gradually decrease, which makes it extremely complicated to control exposure. The most serious problem is that the photos taken with this lens have poor definition and cannot be compared with ordinary lenses.

1902, Charles Allen, an American optician, initially solved the above problems, thus obtaining the first real patent of zoom lens. Allen's patent is to add a movable lens between two fixed lenses. When in use, when the movable lens is far away from the front lens, the focal length will be shortened; On the contrary, when moving in another direction, the focal length increases. In the shortest and longest positions, the image can be "compensated", that is, the focus remains unchanged. In the middle position, although the focus is offset, this offset is acceptable as long as a small aperture is used.

The world's first relatively modern zoom lens (25-80mm, F2.8) was designed by German optician Helmut in 1932 for Siemens' 16mm film camera. This zoom lens is quite complicated. It consists of eight lenses divided into six groups, with a fixed part at the back. Two groups of independently movable lenses perform zooming and focusing functions respectively. One group is called "zoom lens", which can move linearly from front to back to change the focal length. Another group of movable lenses, called "compensation lenses", is located in front of the lenses. Its moving track is eccentric, so it moves forward first and then shifts to ensure that the image has the correct focus at any focal length position. This form of focus correction method is called "mechanical compensation method" because it uses cams to maintain the required nonlinear symmetry.

This method was not replaced by "optical compensation method" until 1950s. The new system uses more than two groups of inner lenses to move synchronously to change the focal length and complete the focal compensation. The optical structure of modern zoom lens is complex. A typical zoom lens generally consists of 15 lenses divided into several groups. A lens with such a complicated structure is much more likely to make mistakes than a simple lens assembly. There is a lot of contact surface between air and glass in zoom lens, so it is very easy to produce unexpected halo. However, this shortcoming was improved with the development of lens coating technology in the 1950s. After adopting coating technology, lens designers can boldly design a large number of optical systems with air-glass interface.

In 1958, Dr Frank Barker of a company in new york, USA, designed the world's first zoom lens for cameras. This 36-82 and F2.8 lens was made for a German 35mm single lens reflex camera, which was the latest optical compensation zoom lens at that time, but it was quite bulky.

1963, Nikon Corporation of Japan introduced the mechanical compensation zoom lens Nicole 43-86 mm F2.8, which opened up a new way for the truly popular zoom lens design. At that time, Nikon explained: "This zoom lens is designed for sports photography and other fields that need high speed and ease of use. But if you want to consider the clarity of the image first, it is best to choose a fixed-focus lens. "

The reason why the design of zoom lens is restored from optical compensation method to mechanical compensation method is because it can make the design of zoom lens lighter, have better focal length compensation effect and facilitate lens designers to perform optical correction more skillfully. Other related technologies adopted at that time, such as antireflection multilayer coating and special optical glass with extremely low dispersion, also made great contributions to improving the imaging quality and miniaturization of zoom lenses in the future.

In recent years, the development and production of zoom lens have made rapid progress, which not only improves the technical performance, but also is more convenient to use. The newly developed zoom lens has the following characteristics: the medium-long zoom lens has a large aperture and its volume is shrinking day by day; Commonly used zoom lenses are high magnification; The focal length develops to the long and short ends, and the macro structure has been greatly improved.