The Zeiss Ikon 18mm f/4 Distagon is an ultra-wide-angle prime lens built around Zeiss's Distagon retrofocus optical concept, which gives the rear element enough back-focus clearance to work behind an SLR reflex mirror. At 18mm with an f/4 maximum aperture, it sits at the wider end of the Zeiss prime range and was aimed at architectural, interior and landscape photographers who needed coverage beyond standard 24mm and 28mm focal lengths.

UK auction data for this lens is thin: only a single hammer result is on record, with one example fetching £500 at a UK saleroom in March 2023. With one data point that price should be treated as indicative rather than a true market median, and what a Zeiss Ikon 18mm f/4 Distagon is worth today in 2026 will hinge heavily on glass condition, mount demand and how clean the helicoid runs — clean, fault-free copies sell for more, while hazy or fungused examples can sell for considerably less.