What Digital Camera reviews the Vario-Sonnar 24-70mm f/2.8 ZA T* SSM lens on Sony a900...
Sony Zeiss Vario-Sonnar 24-70mm f/2.8 ZA T* SSM review
Sony’s top-rank standard zoom comes courtesy of Carl Zeiss and enjoys the same Vario-Sonnar lineage that made the German manufacturer famous throughout the film-camera world. It is also good-looking thanks to a highly streamlined design that features a constant diameter right along the barrel’s length (excluding the mounting flange itself) and a fairly modest length.
The manual-focusing ring is foremost and has a very good feel; the zoom ring is behind and, on the review sample at least, verges on being slightly too heavy to be truly comfortable. AF speed, provided by an aptly-named Super-Sonic Wave Motor, is good and its accuracy is high. Switching between AF and manual-focusing is carried out using a rotating switch that falls right under the user’s left thumb. Sadly, the rotating action is not as easy on the thumb as a simple slide-switch, which is employed by other manufacturers in this application.
Optically, the CZ 24-70mm zoom displays a well-matched set of MTF curves and it appears that Zeiss has gone more for consistency than for a pronounced sweet-spot in image quality. Wide-open and fully-closed resolutions are slightly lower than elsewhere but from f/4 to f/11 the lens stays solidly in the 0.25-0.30 cycles per pixel range at all focal lengths. There is a small amount of chromatic aberration at the 24mm setting, especially towards the edges of the field but this is unlikely to be obtrusive.
Thanks to internal-focusing there is no movement of the front element, nor of the manual-focusing ring, and with only just over 30mm of extension during zooming (despite a continuous forward movement) this is a very compact lens overall. Even more impressive, given its well-contained proportions, is the fact that the Zeiss lens manages to focus slightly closer than competitors from Nikon or Canon’s equivalent zooms.
A classy protective pouch is provided with the lens, as is a petal-shape lens hood.