System and method for measuring accuracy of focus
AssigneePictureFlow LLC
InventorsMichael Tapes, Paul Galburt
Life of this patent
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Abstract
A reliable and repeatable accuracy of focus measurement device to measure the focus accuracy of cameras that employ a different light path between the lens and the focusing sensor and between the lens and the film or image sensor. The measurement device includes a frame having a substantially planar front face with a focusing target located thereon, and at least one depth-of-field ruler coupled to the frame with a transverse axis falling within a front face plane and a long axis that is angularly adjustable with respect to the front face plane.
Claims27
An accuracy-of-focus measurement device for measuring a depth-of-field of a camera having a first light path between a primary lens and a focusing sensor and second light path between the primary lens and an image sensor, the measurement device comprising:
- a frame having a substantially planar front face with a focusing target located thereon;
- a sighting device operatively coupled to the frame and configured to enable a plane of the image sensor of the camera to be aligned substantially parallel with the front face plane,
- at least one depth-of-field ruler coupled to the frame and having a transverse axis falling within a front face plane and a longitudinal axis that is angularly adjustable with respect to the front face plane.
An accuracy-of-focus measurement system for measuring a depth-of-field of a camera, the system comprising:
- a measurement device configured to operate with a camera having a first light path between a primary lens and a focusing sensor and second light path between the primary lens and an image sensor, the measurement device comprising:
- a frame having a substantially planar front face with a focusing target located thereon;
- a sighting device operatively coupled to the frame and configured to facilitate alignment of a plane of the image sensor of the camera substantially parallel with a front face plane;
- and
- at least one depth-of-field ruler coupled to the frame and having longitudinal axis that is at an angle with respect to the front face plane;
- and
- wherein at least one of the camera and the measurement device can be moved in space to align the plane of the image sensor of the camera substantially parallel with the front face plane.
A method for measuring a depth-of-field of a camera having a first light path between a primary lens and a focusing sensor and second light path between the primary lens and an image sensor, the method comprising:
- obtaining a measurement device having a substantially planar front face with a focusing target located thereon and a sighting device configured to facilitate alignment of a plane of the image sensor of the camera substantially parallel with a plane of the front face, and at least one depth-of-field ruler having a longitudinal axis that is at an angle with respect to the front face plane;
- aligning a plane of the image sensor of the camera substantially parallel with the front face plane using the sighting device;
- focusing the camera on the focusing target;
- recording an image of the focusing target and the depth-of-field ruler;
- and
- reviewing the image to determine a center position and width of the depth-of field of the camera on the depth-of-field ruler.
An accuracy-of-focus measurement device for measuring a depth-of-field of a camera having a first light path between a primary lens and a focusing sensor and second light path between the primary lens and an image sensor, the measurement device comprising:
- a frame having a substantially planar front face with a focusing target located thereon;
- and
- at least one depth-of-field ruler coupled to the frame and having a transverse axis falling within a front face plane and a longitudinal axis that is angularly adjustable with respect to the front face plane, wherein the at least one depth-of-field ruler further comprises a repeating pattern of at least two sets of proportionately sized geometric shapes marked thereon, wherein the size of one of the at least two sets of geometric shapes is divisible by an integer from the other of the at least two sets of geometric shapes.
Dependencies are inferred from the claim text.