What are the differences between the OM-2N and OM-2S?
An extensive redesign. The OM-2S is, internally, more like the OM-4 than the OM-2N. Compared to the OM-2N, the OM-2S adds programmed exposure automation (camera chooses both aperture and shutter speed) and a spot meter for use in manual mode. Also, the hot shoe on the -2S is fixed, the ISO range is extended from 1600 to 3200, the viewfinder indicators are LCDs, and the self timer has mirror prefire.