Vari-focal optical system
AssigneeOlympus Corporation
InventorsKeiichi Kuba, Hiroyuki Minakata
Life of this patent
Estimating the term…
Abstract
A vari-focal optical system having a composition comprising at least a first negative lens unit, a second positive lens unit, a third negative lens unit and a fourth positive lens unit, and changes a magnification from a wide position to a tele position by moving at least the second lens unit and the third lens unit. This optical system is configured to have a short total length and reserve sufficient airspaces for the magnification change by locating a front principal point of the second lens unit on the object side of the second lens unit.
Claims30
A vari-focal optical system comprising in order from the object side:
- a first lens unit having a negative a second lens unit having a positive power a third lens unit having a negative power;
- and a fourth lens unit having positive power, wherein a magnification is changed from a wide position to a tele position by moving at least said second lens unit and said third lens unit along an optical axis, and wherein a front principal point of said second lens unit is located on the object side of the second lens unit.
A vari-focal optical system comprising in order from the object side:
- a first negative lens unit;
- a second positive lens unit;
- a third negative lens unit;
- and a fourth positive lens unit, wherein a magnification is changed from a wide position to a tele position by moving at least said second lens unit and said third lens unit along an optical axis, and wherein said second lens unit consists, in order from the object side, of a positive lens component and a negative lens component.
Dependencies are inferred from the claim text.