India
India
By developing fluorite and UD lenses, Canon has been able to suppress the chromatic aberration that was typically found when using conventional lenses. Previous technology was not able to eliminate chromatic aberration and reduce size and weight at the same time, particularly in the case of wide-aperture lenses with low F values. Chromatic aberration is caused by the dispersion characteristics of light. Ideally, all of the light passing through a lens should converge on a single point on the focal plane. Unfortunately, differences in the refractive index of different wavelengths inevitably cause some dispersion. This is the real cause of chromatic aberration (color bleeding). Wavelengths in the blue range of the spectrum are particularly difficult to correct, and cannot be fully resolved merely by combining concave and convex lenses. Inevitably, this creates some chromatic aberration.
To solve the problem, Canon developed the "BR Lens", a composite lens in which BR (Blue Spectrum Refractive Optics) optical elements with anomalous dispersion characteristics that greatly refract blue (short wavelength range) light are sandwihced between concave and convex glass lenses. BR lenses allow for greater freedom in lens design, because the other lens elements can be arranged in ways that may produce considerable chromatic aberration, but the blue wavelengths can then be largely corrected by the inclusion of the BR lens element. By developing new types of lens materials in this way, Canon is introducing lenses that can offer unique optical characteristics, while also improving performance and reducing size.