Contax Planar 50mm f1.7
Zeiss developed the planar design. It is the standard for all 50mm lenses produced today and for good reason. Combine a great design with great glass and great coatings and you have the Contax Planar 50mm. Essentially, this lens is as good as it gets without spending a small fortune. You may notice minor fringing when using this lens on a digital body in harsh lighting, but is easily correctable.