PURPOSE: To provide the photographic lens whose performance is not deteriorated, even if its aperture is enlarged by a small number of lens pieces to the utmost.
CONSTITUTION: In the photographic lens in which a meniscus concave lens 1 whose convex face is turned to an object side and a convex lens 3 are arranged in order from the object side to an image side, and one face or more of lens faces are formed to an aspherical surface, an intermediate lens 2 for correcting an off-axis aberration is interposed between the meniscus concave lens 1 and the convex lens 3. Accordingly, even if the aperture is enlarged, it does not occur that the off-axis aberration increases together with the increase of the aperture, therefore, although the number of lens pieces is as small as possible such as the constitution of three pieces, the performance is not deteriorated even if the FNO is made bright to ≥1.8.
JPS60208719 | TESSAR TYPE PHOTOGRAPHIC LENS |
JPS5950415 | POST-APERTURE TESSAR TYPE LENS |