-Stunning image quality
-Ultra-wideangle
-Manual Focus only (no Autofocus mode)
-Retro-compatibility
-Precision machining
-available in canon, nikon and pentax mounts

The optical and build quality of this lens are nothing short of stunning. There was no hint of visible chromatic aberration (CA) in any of the real-world images, and in technical trials CA even failed to show up numerically in many of the tests.

There are, though, two big drawbacks to the Zeiss 18mm f/3.5. The first is that it has no autofocus (AF) mode so it has to be focused by hand; the second is that it’s at the higher end of the market. Some readers may expect to get automatic focusing in a prime lens at this end of the market, but in this case the money you pay is invested elsewhere.

This is a lens that cries out to be used manually. It feels as if it has been carved from a block of solid metal using micron-precision machining, and both the weight and location of its manual focusing ring are perfect. In front of the ring is a tall flange that supports a reversible (metal) lens hood and also serves to prevent stray fingers from intruding into the wide field of view. If desired, a low-profile filter can be attached to the front of the lens using the 82mm thread provided.

To the rear of the focus ring is a rotating aperture collar, complete with an infrared index and depth-of-field markings for every aperture setting. In a single nod towards automation, the ZF.2 lens (which is an upgrade over the totally manual ZF version) has an electronic interface for automatic aperture operation (in which case the aperture collar must be locked at f/22). There is also a mechanical AI connection to maintain compatibility with older, non-digital Nikon bodies.

It is worth stating that Zeiss denotes each of its different camera-mount optics with a different letter: ZF and ZF.2 lenses are for Nikon F-mount bodies, ZE lenses fit the Canon EF mount, ZK lenses fit the Pentax K bayonet, and ZS lenses feature the classic 42mm screw thread. There is no ZS version of this 18mm f/3.5 lens.

As this lens is an extreme wideangle, great care must be taken to ensure that the camera back is kept vertical if perspective distortion is to be avoided. That said, the 18mms drawing is entirely rectilinear and straight lines remain undisturbed even at the edge of the frame.