Canon develops aberration-reducing optical element

01 Sep 2015

L-Series lens first to feature Blue Spectrum Refractive Optics, for “higher Level” of chromatic aberration correction to boost image quality.

Digital imaging company Canon has developed a lens technology called Blue Spectrum Refractive (BR), which is a new optical element for use in camera lenses that corrects chromatic aberrations to achieve improved imaging.

The optical element offers characteristics that significantly refract blue light, which lies within the short-wavelength range (450–495nm), to achieve what the developer is calling “impressive levels of chromatic aberration correction for outstanding imaging performance”. The BR optical element, positioned between two glass lens elements to create a BR lens, will make its debut in the new EF 35mm f/1.4L II USM wide-angle fixed-focal-length lens, which is scheduled to go on sale in October 2015.

The BR Optics incorporate a new organic optical material with unique anomalous dispersion characteristics for use in camera lenses. The molecular design of BR Optics refracts blue light to a greater degree than other existing optical technologies, such as UD glass, Super UD glass and Fluorite, to minimize color fringing. When placed between convex and concave lens elements made from conventional optical glass materials, BR Optics help to produce sharper images by reducing axial chromatic aberration.

Yuichi Ishizuka, president and COO of Canon USA, commented, “Having produced over 110 million EF lenses since 1987, it is with great excitement that we now introduce this revolutionary new technology. We continually strive to achieve the ideal lens performance, which has driven the development of Blue Spectrum Refractive Optics, found in the new EF 35mm lens."

The new lens also features Canon's proprietary Sub-Wavelength Structure Coating (SWC), applied to the rear surface of the first and second aspheric lens elements to help combat flare and ghosting caused by light rays entering the lens at a large angle of incidence. It also offers best-in-class minimum focusing distance at 0.28m, resulting in an increased maximum magnification of 0.21x which is suitable for capturing close-up subjects.

Design and functioning

About the Author

Matthew Peach is a contributing editor to optics.org.