Zeiss Biogon T* 35mm f/2 ZM on Sony NEX - Review / Lab Test Report
Lens Reviews - Sony Alpha/NEX (APS-C)
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Introduction
Analysis

Review by Klaus Schroiff, published September 2010

The Zeiss Biogon T* 35mm f/2 ZM is a non-retrofocus wide-angle lens for Leica M mount cameras. The basic Biogon design, a Zeiss trademark, has been invented in 1951 by the famous Dr. Ludwig Bertele (1900-1985) who was also the leading designer of the Zeiss Sonnar series. Over time the Biogon has seen several new incarnations and improvements and the ZM 35mm f/2 represents the latest approach. It is, obviously, not a native Sony E-mount lens but you can easily use it on your Sony NEX using a Leica M to Sony NEX adapter (we recommend Metabones adapters).

Such adapted lenses can only be used with manual focusing and "working aperture" - there's no data coupling whatsoever here. However, due to the lack of fast prime lenses it's surely one of the more interesting fall-back solutions for the NEX-system. The field-of-view of this full format lens is equivalent to about 50mm in and in terms of depth-of-field it behaves like a f/2.8 lens in this scope - a rather obvious solution for street and portrait photography for instance. At around 900EUR the Zeiss lens is probably already somewhat off the mainstream as attractive as it may be.

Typical for most Zeiss lenses it's a full-metal construction build to the highest standards - except for the lens cap which is rather crappy. The focus ring operates as smooth as silk (dampened). The aperture is set in 1/3EV steps at the front of the lens. Any change of the aperture is applied immediately so you can check the effect on the depth-of-field on your screen (without the darkening like when stopping down a DSLR with a conventional optical viewfinder). The lens extends very slighty when focusing towards closer focus distances. The front element does not rotate.

Manual focusing may sound like a major annoyance but it is not that bad actually. On Sony NEX cameras you can easily switch to a magnified focus view so accurate manual focusing is really simple ... unless you try to track a moving object of course. We recommend this camera-lens combination for static scenes only.

Specifications
Equiv. focal length52.5 mm (full format equivalent)
Equiv. aperturef/3 (full format equivalent, in terms of depth-of-field)
Optical construction9 elements in 6 groups
Number of aperture blades8
min. focus distance0.7 m (max. magnification ratio 1:18)
Dimensions52 x 68 mm
Weight240 g
Filter size43 mm (non-rotating)
Hoodoptional, barrel shaped
Other features-




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