Get Zeiss Batis and Voigtlander Super Wide-Heliar 15mm f/4.5 Aspherical III at B&H Photo.
The one (and really only) weakness of the Zeiss Batis 18mm f/2.8 Distagon is optical distortion, not to be confused with perspective, which is a function of physical laws (camera to subject distance, inverse square law).
See my in-depth review of the Zeiss Batis 18mm f/2.8 Distagon including the discussion and examples of optical distortion and my comments on the use of software correction in the datasheet.
For architecture or groups of people or horizons, etc, distortion is a serious concern.
Rich G writes:
As always your website proves indispensable as I ponder a question about ultra wide angle lenses for my Sony A7R II.
I am an architectural photographer whose lens arsenal includes the Zeiss Batis 25mm. I am delighted with its performance.
That said, I need an ultra wide angle lens and your initial review of the new Zeiss Batis 18mm gives me pause. The issue is optical distortion. You note in your initial assessment that the 3.2% optical distortion level will likely be an issue for architectural photographers. Indeed!
I’m also considering the new Voigtlander 15mm E Mount lens. I have no doubt that the Zeiss lens is superior in the abstract. But its distortion level is troubling.
My question: do you know anything yet about the distortion figure for the Voigtlander 15mm (E mount)? For my principal need, I would trade superior build for less lens correction.
DIGLLOYD: I don’t know—yet. The Voigtlander 15/4.5 for Sony is on the way for testing.
As a tweaked-for-mirrorless rangefinder design, I don’t expect it to perform nearly as well overall, but as an f/4.5 lens, it’s quite possible that optical distortion has been kept very low, similar to the Zeiss ZM 21mm f/4.5 C-Biogon.