More than the sum of its fine parts
Refraction and colour dispersion
When light hits a glass surface at an angle it changes direction as it crosses the glass. This "refraction" is used by optical designers to influence the path of the light. They use clever lens combinations to create devices such as binoculars or camera lenses, which provide images with as much contrast and detail as possible.
However, as the light is dispersed something disruptive occurs: each colour is sent off in a different direction and the white light is therefore splayed out in all its colours. This "dispersion" creates chromatic aberrations at high-contrast intersections and distorts the image. The result is an image with blurred colours. The same thing occurs in nature when sunbeams are broken and reflected through rain drops: the rainbow then shows all the colours of the spectrum in a neat row, from dark red through orange, yellow, green, blue and indigo to violet. ZEISS minimises this phenomenon through highly complex optical concepts – to give you a detailed visual experience.
Refraction index and Abbe number
The "refraction index" of a lens tells us how far the light is knocked off course upon hitting the glass. Glasses with a high refraction index, for example, can be turned into flat, thin lenses for spectacles that still correct serious visual defects. The higher the refraction index, the higher the colour dispersion, which can have a negative effect. The relationship between these two properties of glass - refraction and dispersion - is described by the Abbe number. A glass that is considered to be "good" from an optical point of view has a high Abbe number.
The name harks back to Ernst Abbe, the co-proprietor of the Carl Zeiss factory when it was first established who was famous for his scientific work and his social commitment.
Multiple lenses to guard against colour aberrations
With a "diverging lens" the centre is thinner than the edge, and things appear smaller when you look through it. A "converging lens" is thicker in the middle than at the edge. It can be used as a magnifying glass, and produces accurate images - but not particularly good ones!
When an optical specialist combines a converging lens with a diverging lens in the correct way he can compensate for the errors of one through the (reversed) errors of the other. A system of this kind that uses a minimum of two lenses is known as "achromatic". To achieve a really good image, however, significantly more lenses need to be used. Your Victory 10x32 T* FL, for example, has eleven lenses on each side – plus prisms. This helps you to enjoy nature with no optical aberrations.