Canon® EOS Digital Photography Photo Workshop

4.3. CANON LENS TECHNOLOGIES

Canon's lens technology leads the industry in producing supersharp, high-resolution pictures. Optical engineering plays a fundamental role in the design of a dSLR camera, and consequently, lenses must also be engineered to even greater levels of precision. Through the development and use of such technologies as diffractive optics, fully electronic mounts, and image stabilization, just to name a few, Canon has stayed at the forefront of the digital market.

4.3.1. FLUORITE AND UD GLASS

How light is refracted depends on the wavelength of the light; this means that where the lens focuses can actually change depending upon specific colors/wavelengths. When the different wavelengths, or colors, are focused at different points, the resulting color can be rendered inaccurately in a phenomenon known as chromatic aberration, and it's especially a problem with longer (telephoto) lenses. Lenses often contain a nonchromatic element that helps to correct chromatic aberration — think of it as a sort of filter. This solution, however, is limited to being used for only two primary (spectral) colors, so without additional optical engineering, at least some chromatic aberration may still exist.

NOTE

For more about chromatic aberration, see Chapter 5.

The mineral fluorite, it turns out, has very low refractive and dispersion qualities — something beyond that of plain optical-quality glass. As a result, Canon has developed a way to integrate fluorite with the optical ...