Zeiss Vario-Sonnar T* 24-70mm f/2.8 ZA SSM (Sony SAL-2470Z) - Review / Lab Test Report
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Review by Klaus Schroiff, published March 2011
Special thanks to Dieter Scherk for providing this lens for testing purposes!
The Zeiss Vario-Sonnar T* 24-70mm f/2.8 ZA SSM is Sony's powerhouse lens in the standard zoom arena. The Zeiss lenses are designed by Zeiss but manufactured by Sony based on Zeiss quality control. As you may have guessed already the "Vario" terms refers to a zoom lens whereas the "Sonnar" (derived from "Sonne" (German) = "sun" in English) specifies a large aperture lens. It is a full format lens so let's have a look now how it perfoms on a Sony Alpha A900/A850.
Regarding its weight of nearly 1kg the Zeiss 24-70mm f/2.8 ZA feels like a massive block of glass. However, this is not overly unusual - the Canon and Nikon counterparts are in the same weight- and size-league. Upon closer inspection
you may be a bit surprised that the lens is not an all-metal construction. The inner tube as well as the lens hood are made of metal indeed but Sony used plastics for parts of the outer body. Plastics may sound bad but it is a high-quality variant ... although it does still not feel really right regarding the positioning of the lens. Unfortunately the lens does not feature any seals which is also a bit of a faux-pas. The zoom ring operates a bit stiff - surely a side-effect of the heavy weight of the glass. The handling of the focus ring is smoother. Typical for most Sony lenses both control rings have an inevitable tendency to collect dust in no time "thanks" to the fluted rubber design.
Looking at the product shots below you may notice that the lens extends when zooming from 24mm towards the long end of the range. The Zeiss uses an internal focusing design so the front element does not rotate during focusing (nor zooming) operations.
One of the interesting features of the lens is the SSM - the SuperSonic AF Motor which is similar to Canon's USM or Nikon's SWM. The SSM of the Zeiss is ultra-fast, near silent and very accurate. On the downside, the focus path is comparatively short - one of the reasons for the fast AF - but this comes at costs of rather difficult manual focusing. Sony/Zeiss also incorporated a focus-lock button plus a dedicated AF/MF switch.
|Optical construction||17 elements in 13 groups inc. 2x aspherical and 2x ED elements|
|Number of aperture blades||9 (rounded)|
|min. focus distance||0.34m (max. magnification ratio 1:4)|
|Filter size||77mm (non-rotating)|
|Hood||petal-shaped (metal), snap-on, supplied|