Rapid focusing varifocal lens assembly

Claim 2

A rapid focus varifocal lens assembly comprising a rotatable and longitudinally slidable outer housing, a varifocal lens system within said housing, including fixed and movable lens elements to vary the focal length of the lens system, a front lens for the varifocal lens system, means including the longitudinal sliding action of the outer housing to move the front lens to focus the lens assembly, and means including the rotary motion of the outer housing to move the varifocial lens elements to vary the focal length of the lens assembly.

Claim 3

A lens assembly according to claim 1 in which the outer housing is carried upon a tubular support, an elongated slot is provided in the inner wall of the outer housing parallel to the optical axis of the system, and a pin slidably carried in the slot extends inwardly and engages a movable element of the varifocal system to shift the said movable element in response to the rotational movement of the outer housing.

Claim 4

A lens assembly according to claim 1 in which the outer housing comprises a control member and a sleeve coupled to each other, and the front lens is carried by the sleeve.

Claim 5

A lens assembly according to claim 2 in which the moveable and fixed lens elements of the varifocal lens are carried within an inner barrel having a helical slot therein to receive the pin therethrough.

Claim 6

A lens assembly according to claim 4 in which a first brake member carried by the tubular support is in frictional contact with the outer surface of the inner barrel to control the rotary movement of the outer housing, and a second brake member carried by the outer housing is in frictional contact with the outer surface of the tubular support to control the longitudinal movement of the outer housing.

Claim 7

A lens assembly according to claim 1 in which the front lens has a travel of the order of 65 mm.

Claim 8

A lens assembly according to claim 1 in which the lens elements in the order of the incident light beam comprise a front lens variator, an erector, a compensator and a ralay; said front lens variator and compensator being movable with respect to the other lens elements of the system.

Claim 9

A lens assemble according to claim 1 in which the varifocal lens system within the housing comprises, in the order of the direction of the incident light, a front lens axially slidable with respect to the fixed lenses within the system, a stationary erector, an axially slidable air spaced compensator, an aperture stop spaced from the compensator, and a rear section of fixed focal length including a relay having two elements therein, said lens system having optical characteristics of the following order wherein: Nd is the refractive index for the D line, V is the dispersion number, Laf stands for Lathanum Flint, K.sub.z F stands for Kurz Flint, Sf stands for Dense Flint, Bk stands for Borosilicate Crown Sk stands for Dense Crown F stands for Crown, R.sub.1 to R.sub.14 are the respective radii of the refractive lens surfaces numbered from front to rear of the lens system. t.sub.1 to t.sub.7 are the respective axial thicknesses s.sub.1 to s.sub.7 are the respective separations from the front to the rear of the lens system. Equivalent focal length of the whole system, (EFL)=f=172-320 mm, Back focal length of the system=202.84 mm, Radius, thickness and separation in millimeters.

Claim 10

A lens assembly according to claim 1 in which the varifocal lens system within the housing comprises, in the order of the direction of the incident light, a front variator lens assembly axially slidable with respect to the fixed lenses within the system, a stationary erector, an axially slidable air spaced compensator, an aperature stop spaced from the compensator, and a rear section of fixed focal length including a relay having six elements therein, said lens system having optical characteristics of the following order wherein ND is the refractive index for the D line, V is the dispersion number, Laf stands for Lathanum Crown F stands for Flint Sf stands for Dense Flint Sk stands for Dense Crown R.sub.1 to R.sub.25 are the respective radii of refractive lens surfaces numbered from fron to rear of the lens system. t.sub.1 to t.sub.14 are the respective axial thicknesses. s.sub.1 to s.sub.18 are the respective separations from the front to the rear of the lens system. Equivalent focal length of the whole system (EFL)=f=80-170 mm Back focal length of the whole system =+86.0 mm Travel of the front lens variator =+48.5 mm Radii, thicknesses and separations in millimeters.