A photographing optical lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof. The second lens element has refractive power. Each of the third through sixth lens elements has refractive power and an object-side surface and an image-side surface being both aspheric. The photographing optical lens assembly has a total of six lens elements with refractive power.

A lens attachment module is configured for coupling with a zoom module of a finite conjugate optical assembly. The lens attachment module includes a lens assembly that has a positive focal length, and exhibits a pupil size of between 16 and 25 mm and a pupil depth greater than 50 mm.

A lens attachment module is configured for coupling with a zoom module of a finite conjugate optical assembly. The lens attachment module includes a lens assembly that has a positive focal length, and exhibits a pupil size of between 16 and 25 mm and a pupil depth greater than 50 mm.

Provided is an optical system including a front unit, an aperture stop and a rear unit which are arranged in order from an object side to an image side. The front unit includes a diffractive optical element, at least one first refractive optical element having a power in the same sign as a sign of a power at a diffractive surface of the diffractive optical element, and at least one second refractive optical element having a power in a different sign from the sign of the power at the diffractive surface. A partial dispersion ratio between a d-line and a C-line and a partial dispersion ratio between a g-line and the d-line of the at least one first refractive optical element and the at least one second refractive optical element are appropriately set.

A photographing optical lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof. The second lens element has refractive power. Each of the third through sixth lens elements has refractive power and an object-side surface and an image-side surface being both aspheric. The photographing optical lens assembly has a total of six lens elements with refractive power.

Provided is a zoom lens, including, in order from an object side to an image side: a first lens unit to a fourth lens unit having negative, positive, negative, and negative refractive powers; and a rear lens group. In the zoom lens, an interval between each pair of adjacent lens units is changed during zooming, the rear lens group has a positive refractive power over an entire zoom range, the third lens unit is configured to move in an optical axis direction during focusing, and each of a focal length of the zoom lens at a wide angle end (fw), and a focal length of the third lens unit (f3) is appropriately set.

A lens with a fixed focal length, includes five lens-element groups, a first front lens-element group, a second lens-element group, a third lens-element group, a fourth lens-element group, and a fifth back lens-element group that is arranged in a stationary manner. Relative to an imaging plane in a lens barrel and both the focusing front group and the focusing back group are movable jointly relative to one another and to the lens-element groups arranged in a stationary manner in order to focus the lens on objects at different object distances. The front lens-element group and the back lens-element group have a negative refractive power.

A lens with a fixed focal length comprising including a first front lens-element group, a second lens-element group, a third lens-element group, a fourth lens-element group, and a fifth back lens-element group. Relative to an imaging plane in a lens barrel and both the focusing front group and the focusing back group are movable jointly relative to one another and to the lens-element groups arranged in a stationary manner in order to focus the lens on objects at different object distances. The front lens-element group has a positive refractive power and the central group and the back lens-element group have a negative refractive power.

A lens with a fixed focal length includes five lens-element groups, a first front lens-element group, a second lens-element group, a third lens-element group, a fourth lens-element group, and a fifth back lens-element group is arranged in a stationary manner. Relative to an imaging plane in a lens barrel and both the focusing front group and the focusing back group are movable jointly relative to one another and to the lens-element groups arranged in a stationary manner in order to focus the lens on objects at different object distances.

A zoom lens system includes a positive first lens group, and a rear lens group behind the first lens group, in that order from the object side. The first lens group includes at least one positive single lens element, a negative meniscus lens element having a convex surface on the object side, and at least one positive lens element, in that order from the object side. A distance between the first lens group and the rear lens group increases upon zooming from the short to long focal length extremities. The following conditions (1) and (2) are satisfied:
fG1/fn<1.50(1), and
65<p.sub.ave(2),
wherein fG1 designates the focal length of the first lens group, fn designates the focal length of the negative meniscus lens element, and p.sub.ave designates the average value of the Abbe numbers with respect to the d-line of the positive lens elements.