The lower the f-number, the higher light intensity at the focal plane.
It had a focal plane of 137 feet (42 m).
The focal plane of the light is 163 ft (49.7 m) above mean sea level.
Out of focus light from points outside the focal plane reduces image clarity.
The focal plane of the light is 33 feet (10 metres).
A focal plane will be on-axis with the entire assembly.
The focal plane is located 73 meters above sea level.
The lighthouse was built in 1874 and its focal plane is 51 meters above sea level.
Both detector focal planes were designed specifically for this camera.
The lighthouse has a focal plane at 137 feet above mean high water.