PURPOSE: To provide a large magnification with simple constitution and to decrease difficulty in working by consisting a 1st lens of a positive meniscus lens the convex surface of which is directed to the object side and the 2nd lens of a biconcave single lens or planoconcave lens the strongly concave surface of which is directed to the image side and constituting these lenses in such a manner as to satisfy respective specific conditions.
CONSTITUTION: This teleconversion lens which constitutes an afocal system as a whole and is placed on the object side of a master lens is disposed, successively from the object side, with the 1st lens having the positive refracting power and the 2nd lens having the negative refracting power, apart at an air spacing provided therebetween. The 1st lens is the positive meniscus lens the concave surface of which is directed to the object side and the 2nd lens is the biconcave single lens or planoconcave lens the strongly concave surface of which is directed to the image side. These lenses satisfy the respective conditions expressed by equation I. In formula, (f) is a focal length; (n) is a refractive index; (v) is an Abbe number; (r) is a radius of curvature; R is the effective radius of the 1st lens. While the lens has the magnification as large as 1.5W1.7 with the simple constitution of 2-groups 2 elements, the lens is small in size and the aberrations thereof are corrected to a level satisfactory for practicable use even when mounted on the master lens.
|JP07120672||HIGH PERFORMANCE PHOTOGRAPHING LENS|
|JP56104311||MODIFIED GAUSS TYPE PHOTOGRAPHIC LENS HAVING LESS DISTORTION ABERRATION|
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