Sigma 18-35mm F1.8 DC HSM A Canon mount lens review: fixed focal length quality in a zoom?By Kevin Carter - Tuesday July 16 2013 Lens Review
Are high quality prime lenses still necessary?
In this set of evaluations, we’ve compared the Sigma zoom with the highest performing full-frame primes of the same focal lengths – 18mm, 24mm and 35mm. While it might seem a little unusual, the lenses (all high speed models) reflect the state of the art in that format and when mounted on an APS-C DSLR offer the same angle of view (at each focal length) as the Sigma.
Sigma 18-35mm F1.8 DC HSM A Canon Versus Carl Zeiss Distagon T 18mm f/3.5 ZE Canon, both mounted on Canon EOS 700D:
At a $1,395, the Carl Zeiss Distagon T* 18mm f/3.5 ZE is one of the finest quality wide-angle primes money can buy, but as a full frame lens it has been designed to illuminate a larger image circle and so requires larger diameter elements and a more complex lens design. As a result, the Sharpness score is good for an ultra-wide 18mm on a full-frame camera but it’s not so great as the equivalent to a 29mm on the Canon EOS 700D.
That is one of the advantages of designing lenses for smaller formats. Despite the relatively high imaging performance of the Zeiss, some chromatic aberration is noticeable in the corners of the frame though distortion and vignetting are at similar levels. Be that as it may, as our results show, at 18mm the new Sigma lens is much more suited to the APS-C format than the Zeiss.
Sigma 18-35mm F1.8 DC HSM A Canon Versus Canon EF 24mm f/1.4L II USM, both mounted on Canon EOS 700D:
Our second comparison is against the full-frame $1,750 Canon EF 24mm f/1.4L II USM, the highest performing 24mm currently available. Again, the same principles apply here as they did for the 18mm Zeiss, but the new Sigma is more than capable of holding its own at 24mm where both lenses would have the equivalent angle of view of a 38mm (in 35mm terms) on the EOS 700D). Apart from a slight increase in sharpness, the Sigma can even boast lower levels of chromatic aberration.
Sigma 18-35mm F1.8 DC HSM A Canon Versus Sigma 35mm F1.4 DG HSM A Canon, both mounted on Canon EOS 700D:
Our final comparison, ironically, has the new Sigma up against the firm’s new 35mm f/1.4 DG HSM A, the best performing full-frame 35mm lens in our database. Although it’s easier to make a high-speed 35mm than either a 24mm f/1.4 or a 18mm f/3.5, the Sigma 35mm is without doubt a superb performer optically and yet the new Sigma 18-35mm zoom comfortably achieves a higher DxOMark Score. The new zoom also has slightly higher levels of sharpness and has the edge in uniformity. Less important perhaps is the superior transmission score, while the differences between distortion, vignetting and chromatic aberration are practically negligible.