The latest f/2 version offers improvements over the Distagon T 25mm F/2.8 ZF.2 option that’s been around since 2009. A DxOMark score of 23 compared to 34 (tested on the D800) demonstrates an improvement in image quality overall, and an increase in Sharpness of 7P-Mpix from 15P-Mpix to 22-P-Mpix is significant.
The latest version improves homogenous edge-to-edge sharpness from f/2.8 to f/5.6, as well as eliminating Chromatic Aberration in the corners. Distortion is roughly the same, but the new lens boosts Transmission from 3.2Tstop to 2.3Tstop, making the new version +1 Stop brighter. All this needs to be placed in the context that the f/2 version is bigger, heavier and costs $700 more than the $1000 Distagon 25mm f/2.8 ZF.2, however.
For “fast” wide-angle primes, Nikon has a challenger with their Nikkor 24mm f/1.4G that boasts a slightly wider focal length, larger maximum aperture and full autofocus. The Nikkor also achieves an overall DxOMark score of 34 to match the Zeiss, and the two lenses are close in terms of Distortion, Chromatic Aberration and Vignetting. The Zeiss version is much sharper though, with that impressive 22P-Mpix score offering +2/3rds resolution over the 17P-Mpix of the Nikkor. The Nikkor is +2/3rds of a stop brighter, however, with an impressive Transmission score of 1.7TStop. Taking all image quality factors into play, these lenses offer the same overall image quality.
Canon offers a couple of competitors in their EF 24mm f/1.4 L II USM and cheaper EF 24mm f/2.8 IS USM, both of which just surpass the Zeiss option for overall image quality and sharpness tested on an EOS 5D MKIII.
If you desire a maximum aperture, the f/1.4 L nudges out the Zeiss in all categories, with the exception of Chromatic Aberration. With an Overall DxOMark Score of 31 to 27 and sharpness scores of 17P-Mpix for the Zeiss, compared to 19 P-Mpix for the EF 24mm f/1.4L, there’s still really not much in it. Both lenses lack homogeneous sharpness at f/2, but it’s still within the realms of acceptable, although the Canon has better control of lens shading at wide apertures between f/2 – f/5.6. The EF 24mm f/1.4L is also +1 Stop brighter, and although costing more at $1749 it benefits from autofocus.
If you can live with a slower f/2.8 maximum aperture, the cheaper $849 Canon EF 24mm f/2.8 IS USM is an excellent alternative option. With an Overall DxOMark Score of 29 compared to 27, it effectively offers the same image quality as the Zeiss – just beating the Zeiss by 2P-Mpix for sharpness and offering better edge-to-edge results at f/2.8. There’s not much in it overall for Distortion, Chromatic Aberration and Vignetting, and although the Zeiss wins +2/3rds Stop for Transmission the Canon 24mm f/2.8 IS USM is the more compact, lighter, cheaper option that also boasts Image Stabilization as well as autofocus.