The Mayima 645 Autofocus lens 28mm comes with  AF D Asph, or Af D LS Asph features; they both have the same aperture range, equivalent focal length,  and minimum focusing but the LS Asph has a leaf shutter, which allows light to pass for a determined period, and the shutter can automatically close after a certain required time interval, controlled by a ring outside the camera.
Mamiya 645 Autofocus Lenses 28mm AF D LS Asph AF D Asph 28mm 4.5-32 4.5-32 17 mm 17 mm 0.35 m 0.35 m No Yes In photography, a shutter is a device that allows light to pass for a determined period, exposing photographic film or a photosensitive digital sensor to light in order to capture a permanent image of a scene. The speed of the shutter is controlled by a ring outside the camera, on which various timings are marked. The shutter is constructed so that it automatically closes after a certain required time interval. 
