Sony Cyber-shot RX1 / Carl Zeiss Sonnar T* 2/35 review: Is this the ultimate moderate wide-angle lens?

By Kevin Carter - Friday, February 22, 2013

Lens Review
Introduction | Sony RX1 lens performance | Sony RX1 lens versus competition | Conclusion

Before we take a look at the lens, we should just recap on the Sony RX1’s sensor performance, which by all accounts was a stunning result. The RX1 has the best performing sensor of any high-end compact or mirrorless camera in our database and indeed comes just behind the Nikon D800/D800E and D600 DSLRs.

sony-c-rx1

The individual scores speak for themselves. The high Portrait score of 25.1 bits is ahead of the Nikon D3x and equal to the new D600, while the huge Dynamic Range of 14.3 Ev is only bettered by the Nikon D800. The Sports (Low-light ISO) use case score is also impressive but it can’t quite reach the same lofty positions of the Nikons. It places the RX1 6th overall in that category, just in front of the inspiring full-frame Canon EOS 6D.

sony-c-rx1
The Sony Zeiss lens has an above average DxOMark score over rival retro-focus types designed for DSLRs, though measurement of Transmission is not possible on a fixed (non-interchangeable) lens.

With a high overall DxOMark score of 33, the Carl Zeiss Sonnar T* is a superb performer optically. That score puts it comfortably ahead of the $1,850 manual focus Carl Zeiss Distagon T* 1.4/35 (35mm f/1.4) on a Nikon D3X, which achieved a DxOMark score of 30.

That wasn’t the only 35mm f/1.4 lens that achieved that score, though. The manual focus Samyang AS UMC and the new autofocus Sigma DG HSM model also attained an overall DxOMark score of 30 when measured on a D3x and Canon EOS 5D Mk II, respectively.

Individual metrics show the fixed Sonnar of the RX1 to have excellent sharpness, measured at high 18P-Mpix in our labs. The Zeiss Distagon T 35mm f/2 ZE Canon, a retro-focus design incorporating nine elements (with one lens made of low-dispersion glass) achieved a moderate 15P-Mpix score when measured on a Canon EOS 5D Mk II. However, at maximum aperture the sharpness could be improved across the field, it’s sharp in the centre but acutance falls away to the edges and corners.

sony-c-rx1
At maximum aperture the Sony Zeiss Sonnar lens performs well centrally though sharpness is not uniform across the field, as you might expect (but it’s a good result all the same)

Also bear in mind because the Sonnar is fixed, non-interchangeable lens we’re unable to measure Transmission. As a result, the overall DxOMark score doesn’t take that into account. A poor result could lower the score, but the opposite is also true.

Measured at 0.7%, the lens has some slight but still noticeable barrel distortion. It’s not complex, or ‘moustache’ type distortion and so it would be easy to correct in software.

sony-c-rx1
Some slight barrel distortion is noticeable but it’s average for a lens of this focal length.

Chromatic aberration is slightly higher than we might expect. Although it’s much lower than some high-grade zooms, for a modern prime it’s a slightly surprising result.