The Biogon T* 2,8/21 ZM offers outstanding performance and extreme resolving power even when shot wide open, with virtually no distortion, excellent control of flare and ghosting and superb contrast rendition across the entire frame. The slim lens design is easy to grip and focus, and uses a standard 46 mm filter diameter similar to many of the other ZM lenses and allows filters to be interchanged between the lenses. The lens is rangefinder coupled for easy focusing and the optional 21 mm viewfinder is available for accurate image composition. The Biogon T* 2,8/21 ZM is suitable for many different wide-angle applications including reportage work, landscape and architectural photos.
|Focal length||21 mm|
|Aperture range||2.8 – 22 (1/3 steps)
|Focusing range||0.5 m – ∞
|Number of elements/groups||9/7
|Image ratio at close range||1 : 21|
|Coverage at close range||47 x 71 cm|
|Angular field, diag./horiz./vert.||90°/80°/58°
||M 46 x 0.75
|Dimensions (with caps)||ø 53 mm, length 75 mm
The range of ZEISS T*® lenses offers the highest possible standards in terms of performance, reliability and, of course, image quality. Quite simply, they are superior in every way. You can count on highly advanced flare control for crisp and brilliant images, for example. And virtually zero geometric distortion, ensuring precise accuracy when reproducing shapes – especially useful when photographing products and architecture.
Dramatic perspectives and a view from extraordinary image angles – ZEISS lenses open up new composition possibilities. Distortion would disrupt the composition because straight lines, whose image does not go through the image center, would be reproduced with a curved shape. This annoying effect is accordingly and largely compensated through elaborate optical designs at all focal lengths.
The optical elements of ZEISS lenses feature T*® anti-reflective coating on all surfaces and an optical design that guarantees images of superior brilliance at all times, even in unfavourable lighting conditions. We apply the anti-reflective coating to the lens surfaces by the vapour deposition of extremely thin, transparent layers on the glass. In this process, special substances are vaporized with extremely high energy in a high-vacuum environment and are subsequently deposited on the glass surfaces, one after another, as layers with precisely controlled thicknesses to achieve the desired reduction of reflective properties. The first coating techniques were employed by ZEISS as long ago as in the 1930s.
Rich, vibrant colors are vital to creating a lasting impression. Stray light in the lens, however, would lead to a brightening of the image, which is particularly visible in shadow areas. Image contrast is lowered; the image appears dull and bleached. We combine various, elaborate techniques to reduce unwanted stray light.
ZEISS T*® ZM-mount lenses are specifically designed to minimize focus shift with aperture changes – an important innovation with big benefits for rangefinder photography. As a result, you can expect improved accuracy of the rangefinder-defined focus. While the precise 10-blade aperture with 1/3 stop interval click stops ensures exact exposure.