The apertures of lenses for the OM series of cameras all seem to operate in the opposite way to say Nikon, Pentax or Minolta in that when the shutter is released the apperture pin moves away from the apperture mechanism which is them closed by a spring. With the others the pin moves against the aperture pin so forcing the lens to close down.

I would have thought that the OM method would give rise to less vibration than the others. For what it's worth, I never had a problem with OM cameras and vibration anyway. What I did find though was the diaphragms of OM lenses were more prone to becoming 'lazy' and slow to close