And,

http://www.zeiss.com/c12567a8003b58b...highlight=spur

"Resolving Power Record with ZEISS Biogon T* 2,8/25 ZM

When Hasselblad staff photographer Jens Karlsson took demo photos for the first Zeiss Ikon brochure in 2004, his photo of the carousel, taken with the ZM-Biogon 25 stood out for its enormous detail and clarity. So we used a ZM-Biogon 25 in a recent test to determine maximum resolving power. The high resolution film of choice was the SPUR Orthopan UR supplied and processed by SPUR.

The result was a whopping 400 lp/mm on film, recorded with the Biogon 25 at f/4 in the center of the image. This value, 400 lp/mm, corresponds to the maximum resolution theoretically possible at f/4; in other words it represents the calculated "diffraction limited" performance at this aperture. It is noteworthy that this test was conducted with a production lens on a production camera, indicating that the film was precisely positioned and flat.

Let's just say that this test is relevant to everyday photography the same way the top speed of a Formula 1 race car relates to everyday personal transportation. Of course, many people enjoy watching Formula 1 races ..."