The 50/3.5 Zuiko macro is a floating element design. It is sharp at all distances. When Nikon changed from the black front 55/3.5 Micro Nikkor Auto (compensating aperture design) to the 55/3.5 Micro Nikkor P it improved the performance for distant subjects. Some people claim that the compensating 55/3.5 is better in the very close range than the later 55/3.5s. I find performance at infinity to be excellent with the P, the PC, the 'K' and the AI 55/3.5s. As has been mentioned, the 55/2.8 AI and AIS lenses also have a floating element design and are sharp at all distances. Other short macro lenses I have found good at infinity include the 55/3.5 Konica Macro Hexanon, the 50/3.5 Canon FL, Canon FD SSC and New FD, the 55/2.8 Vivitar macro, the 55/2.8 Soligor macro and the following Minolta 50/3.5 macro lenses: pre-set, MC Celtic and MD. The MC Rokkor, MC Rokkor-X and MD Rokkor-X lenses all have the same design and should be fine at infinity.