AUTOFOCUS CALIBRATION FOR LONG LENSES

摘要

A method for calibrating a focus point for a camera lens may include capturing a reflection of a focus point measuring device that is affixed to the camera. The method may include evaluating a captured image of the reflection to measure a calibration amount for a focus point, and adjusting a focus point of a lens of the camera by the calibration amount. The focus point measuring device may include a substantially planar target surface defining a plane, and a ruled target surface inclined at substantially 45° to the substantially planar target and extending through the plane thereof, marked to indicate respective distances in front of and behind the plane. The device may further include a fixture for holding the substantially planar target surface and the ruled target surface in a defined orientation to the camera, enabling performance of the method.

主权项

1. An apparatus, comprising:
a substantially planar target surface defining a plane; a ruled target surface inclined to the substantially planar target and extending through the plane thereof, marked to indicate distances in front of and behind the plane; and a fixture for holding the substantially planar target surface and the ruled target surface in a defined orientation to a camera, whereby a reflection of the substantially planar target surface and the ruled target surface is visible through the a lens of the camera pointing at a mirror along a line of sight, in which reflection the substantially planar target surface and the ruled target surface are disposed in a field of view along the line of sight and the substantially planar target surface is substantially perpendicular to the line of sight.