Introduction The Zeiss Distagon T* Otus 1,4/55 is the first of a new series of high-grade lenses from the maker optimized for the next generation of high-resolution DSLRs. This fast standard adopts the firm’s retrofocus Distagon type optical construction, a design previously only found on wide-angle models. It has a complex construction consisting of 12 elements in 10 groups, and features no less than six elements made from anomalous partial dispersion glass and one lens made with an aspherical surface. Although a manual focus design it has a ‘floating elements’ for close range correction and a