Super Spectra Coating
Canon has identified four criteria for the perfect photographic lens:
- Light rays from a single point on the subject should converge on a single point after passing through the lens
- Any flat surface perpendicular to the optical axis should be flat
- Any flat object perpendicular to the optical axis should be reproduced without distortion
- Subject colours must be accurate
Canon identified the last requirement as a major development objective. Canon set its own standard for uniform colour reproduction in the 1960s, when professional photographers first used colour reversal film. Canon began with the assumption that any lens would provide the same colour reproduction. However, in order to evaluate colour precision, some colour reproduction and balance criteria must be established. Canon began by investigating the properties of sunlight, specifically the changes in light over the course of a year as air quality and the angle of the sun change. In addition to repeated test photos, Canon solicited feedback from a large number of panellists. The data gathered during this process was then converted into numerical values, ultimately establishing Canon's own colour reproduction standard for lenses. When the photographic industry adopted the ISO Colour Contribution Index as the industry standard in the 1980s, they used values that were nearly identical to those used by Canon, though Canon's standards are a little stricter, with less tolerance for variations.
Canon developed Super Spectra Coating (SSC) technology to help it meet this stringent colour reproduction standard. This multi-layered coating forms a hard, durable lens surface with stable properties, reducing the likelihood of lens flare and ghosting caused by reflections on the lens surface. When used on digital cameras, which are particularly prone to lens flare and ghosting, Super Spectra Coating provides optimal colour balance. Efforts to improve coating performance continue as Canon strives to adapt to changing times and meet the changing needs of professional image makers.