Canon recently announced that 2021 marks the 50th anniversary of the release in 1971 of the FD55mm f/1.2AL, the company’s first lens for interchangeable-lens SLR cameras that employs an aspherical lens element. Aspherical lens elements are not only used in the company’s interchangeable-lens SLR cameras, but also broadcast lenses, semiconductor lithography systems, telescope mirrors and a wide variety of optical products.
Aspherical lenses possess a curvature that are ideal for gathering light at a single point. From the f/2.8L IS USM zoom lens series for professional and enthusiast users—the RF15-35mm f/2.8L IS USM (released in September 2019), RF24-70mm f/2.8L IS USM (released in September 2019) and RF70-200mm f/2.8L IS USM (released in November 2019)—to the RF28-70mm f/2L USM (released in December 2018) which realizes a fast f/2 aperture across the entire zoom range, Canon’s aspherical lenses help reduce various types of aberration and achieve high image quality.
The inherent characteristics of spherical lenses result in the lens being unable to focus parallel rays of light in their complete form at a single common point. Due to the lens’ spherical-shaped surface, blurring of captured images—known as spherical aberration—and other optical aberrations tend to occur in the captured image. In order to correct spherical aberration, multiple spherical lenses must be used and placed in a specific configuration. However, thanks to their unique properties, the same results can be achieved using only a single aspherical lens. In 1963, Canon embarked upon a program of sophisticated lens research and development in order to develop this “dream lens” that could focus all incident light on a single point and create a faithful, clear image.
In order to mass-produce aspherical lenses, Canon needed processing technology that was precise to within less than 0.1 micrometers1, as well as high-precision measuring devices that could measure to within 0.01 micrometers. Through repeated cycles of design and processing methods, the company finally succeeded in creating the technology needed to mass-produce aspherical lenses. In March 1971, Canon’s first interchangeable-lens SLR camera employing an aspherical lens was released—the FD55mm f/1.2AL.
Then, in 1973, Canon further enhanced the precision of its lens processing technology with the development of the ALG-Z nanometer2level ultra-high-precision aspherical lens grinder. The next leap forward happened in 1985, when the company successfully implemented the large-diameter glass mold (GMo) aspherical lens element into the New FD35-105mm f/3.5-4.5 (released in December 1985), the world’s first interchangeable lens for SLR cameras to include a GMo aspherical lens.
Ever since, the technologies used to form and measure aspherical lenses have played a vital part in Canon’s efforts to realize high-performance lenses.
Going forward, Canon will continue to polish its optical technologies in order to create products and technologies that help meet our customers’ wide-ranging needs.