On June 5, 2000, about 0030 eastern daylight time, a Bell 407, N234BH, operated by Ben Hill Griffin Inc., was substantially damaged when it collided with the ground during approach to landing near Lake Placid, Florida. The airline transport pilot-in-command and the non-helicopter rated pilot passenger received minor injuries. Night visual meteorological conditions prevailed, and no flight plan was filed for the local aerial observation flight being conducted under Title 14 CFR Part 91. The flight originated from Avon Park, Florida, at 2320. According to the pilot, he circled an area surrounded by wild fires on the operator's property for approximately 25 minutes. Visibility in the area was limited due to smoke present from the fires. While at an indicated altitude of 1,000 feet above mean sea level (msl), with a ground elevation of 20 feet msl, the pilot initiated an approach to a grass landing zone. The pilot stated that both himself and the passenger made visual contact with the ground at 600 feet; however, he lost visual contact with the ground at 500 feet. The passenger advised the pilot that he maintained contact with the ground and he continued to call out altitudes every 50 feet while the pilot verified the call outs. Shortly after the passenger called out 450 feet, the helicopter impacted the ground while traveling at a speed of approximately 35 knots. The pilot stated that there were no mechanical malfunctions or component failures with the helicopter. In an interview following the accident, the pilot reported that the altimeter setting was approximately 300 feet off. He also stated that the remote area in which he was flying was very dark with limited lighting in the area.