Zeiss Distagon T* 24mm f/2 ZA SSM (SAL-24F20Z) - APS-C Review / Lab Test
Lens Reviews -
Sony Alpha/NEX (APS-C)
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Review by Klaus Schroiff, published December 2010
Lens kindly provided by Dieter Scherk!
Ever since the introduction of the Zeiss ZA 135mm f/1.8 and ZA 85mm f/1.4 the Alpha community awaited further fast prime lenses made by Zeiss - after all these were promised soon after the start of the Alpha system. Well, the wait is over ... Sony finally unleashed the Zeiss Distagon T* 24mm f/2 ZA SSM (SAL-24F20Z) upon us. It is a full format lens and as such usable both on full format and APS-C format DSLRs. This test report describes the performance on an APS-C DSLR where its field of view is equivalent to about 36mm (full format) so it behaves like a moderate wide angle lens typically used e.g. for street photography.
Regarding its max. aperture of f/2 it doesn't really qualify as "ultra large aperture lens" anymore but this "limitation" may be actually a quite smart decision upon 2nd thought. Thanks to the more moderate aperture the Zeiss lens is a little cheaper than its f/1.4 rivals made by Canon and Nikon and - probably more important than that - it is far simpler to design. At f/1.4 the manufacturers are struggling to overcome heavy aberrations (optical defects) in order to provide some sort of usable image at max. aperture whereas the optical situation is far more forgiving when starting at f/2.
The build quality of the lens is nothing short of outstanding. The lens body is completely made of metal and that's including the smoothly operating fluted focus ring. The physical length of the lens remains constant at all focus setting and there's also no moving inner lens tube. On the downside Sony does not mention any weather sealing which may be a little disappointing for some. The petal-shaped lens hood is made of good quality plastics.
The Zeiss lens features Sony's "supersonic motor" (SSM), an AF drive based on ultrasonic waves similar to Canon's USM and Nikon's Silent Wave drive. The AF is both very fast and virtually silent. DMF ("Direct Manual Focusing") is supported.
The Zeiss lens can also be used on the Sony NEX system using the Sony LA-EA1 Alpha-to-NEX adapter. The AF remains functional and it performs better than e.g. the Sony 50mm f/1.8 DT that we've tested here recently. However, don't expect an SLR-like AF quality here. The combination may look a little odd but it remains viable option here as well.
|Equiv. focal length||36 mm (full format equivalent)|
|Equiv. aperture||f/3 (full format equivalent, in terms of depth-of-field)|
|Optical construction||9 elements in 7 groups inc. 2x aspherical + 2x ED elements|
|Number of aperture blades||9 (rounded)|
|min. focus distance||0.19 m (max. magnification ratio 1:3.4)|
|Dimensions||78 x 76 mm|
|Filter size||72 mm (non-rotating)|
|Hood||petal shaped, supplied|