Carl Zeiss Distagon T* 25mm F2.8 ZF (Nikon AiS)

To sell you this lens, I first have to sell you the focal length. 25 mm is somewhere between moderately wide and really wide. It is definitely an in-betweener, perhaps even an oddball, bringing together the expansive scope of, say, a 20 or 21 mm with the relative ease-of-use of a 28 mm. I find it a natural focal length for both indoor and outdoor shots, especially bigger landscapes with lots of sky or conversely tight spaces indoors. Unlike a 20 mm you don't have to get too contrived with the foreground composition to fill the frame.

It doesn't take much research to discover that the Zeiss 25/2.8 ZF is not especially well-regarded optically.  Soft corners and vignetting wide open are found to be particularly dire. Well, okay, but this is normal behavior for a lens of this focal length. Look at it this way: a lens doesn't have to be good at everything all the time. This Zeiss is meant to be used at f/8 for maximum edge-to-edge sharpness, while the center remains sharp all the way down to f/2.8. The key point is unlike, say, the Nikkor AF or AiS 24/2.8, CA is very low at all apertures. Distortion is also relatively well controlled.

So while I can't say I prefer this lens to the 35/2 Distagon, it's a good, useful lens that performs very well when used at the aperture appropriate for the scene. Physically it is a little smaller than the 35 mm, and has a "secret weapon": close focusing down to 17 cm. It is the cheapest of the ZF lenses after the 50/1.4, and can sometimes be found at bargain prices on the used market. Mine was just $350.

Carl Zeiss Distagon T* 25mm F2.8

Note: don't bother with this lens as a 35 mm equivalent on crop format cameras. The barrel distortion which has a handlebar shape on full-frame is distractingly curved on APS-C, and even the central sharpness does not impress at the higher pixel densities found in most crop sensors. It's a lot of money for little return.