| 摘要 |
PROBLEM TO BE SOLVED: To provide a wide-angle zoom lens having a bright and uniform open F value throughout the whole zoom range and an optical instrument having the same, in which a drop in peripheral light intensity at the wide angle end is made less noticeable and whose performance is made high.SOLUTION: A zoom lens has a positive lens group arranged closest to the image side. At the position closest to the image side of a lens group adjacent to the object side of the positive lens group, a variable diaphragm is provided which determines an F value during open use times at least at the wide angle end, and a surface apex position on the object side of the positive lens group is arranged closer to the image side than the variable diaphragm position at the wide angle end and arranged closer to the object side than the variable diaphragm position at the telephoto end. |
