The pilot reported he entered a left traffic pattern for runway 30 during night visual meteorological conditions. Shortly after turning final approach, the airplane impacted the terrain. The pilot thought he had sufficient altitude during the initial phase of the final approach based on his altimeter indication. The airplane sustained substantial damage to the right wing and fuselage, and the three occupants were not injured. A postaccident examination of the airplane revealed the pilot had an improper altimeter setting that resulted in the altimeter indication error of +800 ft mean sea level, and the airframe and engine revealed no evidence of mechanical failures or malfunctions that would have precluded normal operation. The pilot stated that he must have had the wrong altimeter setting for the destination airport. Runway 30 was equipped with medium intensity runway edge lights, and a 4-light precision approach path indicator light system.