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More than the sum of its fine parts

An optic is more than fine glass and precise mechanics. The choice of over 180 different types of glass and an exhaustive optics calculation add up to an optical concept. Your ZEISS product is thus based either on the brilliant FL concept, the colour-neutral HD concept or the unrivalled brightness of the HT concept. Benefit from our optical expertise with an unparalleled visual experience.

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.

Transmission in focus: ZEISS HT

High transmission values for bright, detailed images are among the core skills with which ZEISS constantly sets new milestones. It all began with a "process to increase the light transmission in optical parts”, for which a patent was filed by ZEISS in 1935. This laid the foundation for the coating technology.

Further innovations followed, with the decisive performance feature - image brightness - always the main focal point. ZEISS binoculars for hunting are therefore fitted with the large Abbe-König prisms, which operate without light-absorbing mirrors and are the brightest roof prism system available.


For many years the maximum levels of contrast and brightness were defined by the Victory FL binoculars. A small percentage of light loss through absorption as the light passed through the glass was accepted as inevitable. Until, that is, SCHOTT AG - a sister company ­in the Carl Zeiss Foundation - developed new optical lenses with the additional "HT" or High Transmission feature.That was the trigger for the development of the ZEISS HT products.


ZEISS HT – innovative optical design with HT lenses by SCHOTT - represents a light transmission capability that was previously unheard of. It was developed for use when hunting, to ensure that critical details can still be seen even in the deepest twilight. The new HT binoculars and riflescopes also have all the benefits of the FL models, such as fluoride lenses for maximum image sharpness and colour correction, advanced T* coatings, inverting prisms with low light capability and the LotuTec® coating for clear visibility whatever the weather. However, the real advantage lies in the fact that these lenses, with their unrivalled brightness, have set new standards, with more than 95% in the field of light transmission.


Exclusive lenses to guard against chromatic aberrations

Instead of using lens combinations alone to optimise the image quality, optical designers like to use additional lenses with very low dispersion rates (known scientifically as "anomalous partial dispersion"). This is often called "ED glass", standing for Extra low Dispersion.

The ZEISS Conquest HD binoculars use this kind of lens. This gives them the very high resolution (HD = High Definition) and the well-balanced colour reproduction. The finest details are shown with great sharpness and you can see nature in clear, neutral colours.


Brilliant up to the last detail

In nature, light is "white" light, a mix of all the colours of the spectrum. These colours are deflected in different ways when they pass through a lens, through a prism and through water droplets. The experts call this "dispersion". It is the dispersion of light into the colours of the spectrum that causes rainbows, for instance. In optical images, however, this effect leads to blurring and unwanted colour fringing on image contours. The result is that the details become less easily detectable.

Skilfully combined optical systems

The phenomenon of fringing can be significantly mitigated by cleverly combining lenses of different glass materials. Known as an "Achromat" optical system, this is nowadays standard for most applications in observation optics and photography. However, it still displays a low residue of chromatic aberration.
Further optimization and enhancement is only achieved through the use of special types of glass with so-called "anomalous partial dispersion". Here, right from the outset the occurrence of unwanted colour splitting is much lower than in all other types of optical glass. Among such select materials is glass that contains fluoride. Optically this kind of glass is almost perfect, but it is also significantly more costly and requires far more sophisticated processing.

Guarantee of superior image quality and brightness

The quality of optical imaging is not only determined by the glass the lens is made of. It is only when these fluoride lenses are carefully integrated with coordinated optical systems as well as the right coating technology that the sum total of all these elements combines to form the unique ZEISS "FL Concept". This is your guarantee of superior image quality and brightness.
The superior performance of this concept is demonstrated in very sophisticated optical systems, especially for very large lens diameters, very high magnifications and very wide fields of view. You will therefore only find the "FL quality seal" on selected products in the field of spotting scopes and binoculars, thereby forming the reference class in the domain of observation optics.


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