Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
238 words
A method of calibrating a graphic arts camera, of the type comprising a ground glass surface defining a film plane, a movable copy board, a movable lens board disposed between said ground glass surface and copy board, and controls including a camera scaling system for positioning said copy board and lens board relative to one another and relative to said film plane; said method comprising the steps of preparing a target which includes a first indicia representing an optical axis and a second high contrast indicia displaced from said first indicia and positioned at an off-axis location at which the effects of chromatic aberration for an apochromatic lens of particular effective focal length are minimum at a lens conjugate of 1:1; mounting an apochromatic lens of said effective focal length on the lens board, mounting said target on said copy board with the optical axes of said lens and target in alignment with one another and with the said copy board, lens board and ground glass surface in plane parallelism, setting said lens to its maximum aperture size, adjusting the positions of said lens board and copy board to the 1:1 lens conjugate, viewing color fringing effects in a magnified image of said second indicia on said ground glass while conducting said adjusting step until the observed color in said magnified image corresponds substantially to the center of the visible spectrum, and thereafter setting the camera scaling system.
Claim 2
Independent Claim
238 words
A method of calibrating a graphic arts camera, of the type comprising a ground glass surface defining a film plane, a movable copy board, a movable lens board disposed between said ground glass surface and copy board, and controls including a camera scaling system for positioning said copy board and lens board relative to one another and relative to said film plane; said method comprising the steps of preparing a target which includes a first indicia representing an optical axis and a second high contrast indicia displaced from said first indicia and positioned at an off-axis location at which the effects of chromatic aberration for an apochromatic lens of particular effective focal length are minimum at a lens conjugate of 1:1; mounting an apochromatic lens of said effective focal length on the lens board, mounting said target on said copy board with the optical axes of said lens and target in alignment with one another and with the said copy board, lens board and ground glass surface in plane parallelism, setting said lens to its maximum aperture size, adjusting the positions of said lens board and copy board to the 1:1 lens conjugate, viewing color fringing effects in a magnified image of said second indicia on said ground glass while conducting said adjusting step until the observed color in said magnified image corresponds substantially to the center of the visible spectrum, and thereafter setting the camera scaling system.
Claim 3
Dependent Claim
87 words
The method of claim 1 wherein said step of preparing a target comprises locating a plurality of different second indicia differently displaced from said first indicia at a plurality of different off-axis locations at which the effects of chromatic aberration for a plurality of apochromatic lens of different effective focal lengths respectively is minimum, said viewing step comprising the step of viewing a magnified image of a particular one of said second indicia associated with the focal length of the lens then mounted on said lens board.
Claim 4
Dependent Claim
97 words
The method of claim 2 wherein said adjusting step comprises mounting a first precision ruler on said copy board to image both said first ruler and said target on said ground glass surface, mounting a second precision ruler on the roughened interior surface of said ground glass in parallel relation to the image of said first ruler, repositioning said copy board wHile viewing the second ruler and imaged first ruler on said ground glass surface to adjust image size, and repositioning said lens board while viewing said imaged target on said ground glass surface to adjust focus.
Claim 5
Dependent Claim
24 words
The method of claim 3 wherein said steps of repositioning said copy board and repositioning said lens board are conducted in alternative repeated sequence.
Claim 6
Dependent Claim
36 words
The method of claim 2 wherein said step of preparing said target comprises generating a plurality of different diameter circles, concentric with one another and with said first indicia, to produce said plurality of second indicia.
Claim 7
Dependent Claim
72 words
The method of claim 5 wherein said step of preparing said target further comprises the step of superimposing a high-contrast checkerboard pattern on said plurality of circles, said viewing step comprising initially viewing the image of said checkerboard pattern on said ground glass surface during said adjusting step and thereafter viewing the magnified image of a portion of a selected one of said concentric circles during a continuation of said adjusting step.