| 摘要 |
PURPOSE:To produce spherical aberrations of higher orders and nevertheless prevent focus position from changing from that before mounting of an attachment lens even if it is mounted, by constituting the attachement lens by two pieces of a concave lens and a convex lens, cementing two pieces of these lenses or disposing these by leaving a suitable air spacing. CONSTITUTION:This is so constituted by a concave single lens 1 and a convex single lens 2, as an attachment lens to be mounted on the object side of a main lens 3, that it becomes nearly afocal and its angular magnification becomes nearly 1, wherein these are so constituted as to satisfy the condition formulas I and II, when the radii of curvature of the face on the image side of the concave lens 1 and the face on the object side of the convex lens 2 are defined as rA, rA', respectively and the axial distance from the face on the object side of the convex lens 2 up to the diaphragm of the main lens 3 is defined as SIGMAdA. |
