Camera Viewfinder Using Tilted Concave Mirror Erecting Elements

Donald DeJager

doi:10.1117/12.959096

16 September 1980 Camera Viewfinder Using Tilted Concave Mirror Erecting Elements

Donald DeJager

Proceedings Volume 0237, 1980 International Lens Design Conference; (1980) https://doi.org/10.1117/12.959096
Event: 1980 International Lens Design Conference, 1980, Oakland, United States

Abstract

The camera viewfinder would consist of a two-element objective lens, a field stop, a tilted concave mirror, an aperture stop, a second tilted concave mirror, and a two-element eyepiece. This forms a Z shaped configuration with the mirrors at the corners of the Z. The two mirrors, with the aperture stop midway between them, form a 1:1 telescopic erecting relay system. Two types of mirrors are studied: spherical and parabolic. The main problems encountered in the spherical mirror system are axial astigmatism and field tilt, both caused by the tilted mirrors. By using confocal, coaxial, decentered parabolic mirrors, with the aperture stop at the common focal point, the axial astigmatism can be eliminated; however, the field tilt problem is aggravated. By rotating the axis of the second parabolic mirror about the common focal point, the field tilt can be minimized, and the astigmatism in all beams eliminated. This last configuration is, however, plagued by distortion and coma. We conclude that none of these systems is satisfactory for image quality.

Citation Download Citation

Donald DeJager "Camera Viewfinder Using Tilted Concave Mirror Erecting Elements", Proc. SPIE 0237, 1980 International Lens Design Conference, (16 September 1980); https://doi.org/10.1117/12.959096

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