The Carl Zeiss Vario-Tessar FE 4/24-70mm ZA OSS lens for full frame Sony Alpha 7 cameras manages what very few manufacturers even contemplate doing: mimicking the quality of a prime lens in the wide-angle and short telephoto focal lengths and anything in between.
Is this lens not quite as good as a 24mm or 35mm or 50mm or 70mm prime? Yes, it is not; if it were, then there would be no reasons to own prime lenses
Is this lens better than the Sony 3.5/5.6 28-70mm FE OSS lens? Yes, absolutely.
So why buy the Carl Zeiss lens over the Sony?
At first glance you might ask yourself the question is the Carl Zeiss lens really worth 4 times more than the Sony equivalent? Well, the answer lies in the details.
Firstly there is a difference in focal length. There is a very big difference between using a 24mm wide angle to a 28mm wide angle.
Secondly the Carl Zeiss lens has a constant maximum aperture of f4 where as the Sony varies from 3.4 to 5.6 depending on focal length.
Size and weight wise the Sony is slightly lighter and the Carl Zeiss lens is a little bigger (it is a wider zoom range) and also a little heavier as it is a much better build, using stronger materials. The weather seal is pretty much the same and the filter size on the Carl Zeiss lens is larger. Both come with front and rear caps and a lens hood and the Carl Zeiss lens also comes with a leather bag.
The centre sharpness is far superior on the Carl Zeiss lens but the edge sharpens is what has drawn a bit of flack from other reviewers who find that the Carl Zeiss lens is not as good as they expected, compared to a prime. Yes, compared to a prime, that is true, however does it matter in practice? I’d say no. With the incredible versatility of this zoom range and the inherent sharpness and superior colour rendition and anti-flare coating I’d have the Carl Zeiss version over the Sony Zoom anytime and I absolutely love the bokeh of the Carl Zeiss lens. I do use a Carl Zeiss 35mm quite often with my Alpha 7R and I love it; it enables me to carry a camera package that is considerably smaller and much better suited to street photography, but if you’re looking for an all-rounder then I don’t think you can beat the 24-70mm at this stage.
So would I buy the Carl Zeiss over the Sony zoom? Yes, after all, I did. (I bought the Sony first, then tried out the Carl Zeiss and gave the Sony lens away)