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 in harsh lighting on a digital body, but is easily correctable. Though not designed for close focus, the Planar will produce nice macro images with extension tubes. Shoot at f4 or higher to avoid bokeh fringing.