Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
160 words
A zoom finder comprising, beginning on an object side, a first lens component having positive refractive power, a second lens component having negative refractive power a third lens component having negative refractive power and a fourth lens component having positive refractive power, wherein said Albada system is constructed by said third lens component and said fourth lens component and said zoom finder with an Albada System is arranged to be zoomed by moving said second lens component, and satisfies the following conditions: ##EQU3## where the reference symbol RA is the radius of curvature of a surface of an object side of the fourth lens component, the reference symbol R B is the radius of curvature of a surface of an image side of the fourth lens component, the reference symbol n 2 is the refractive index relative to the D-lines of the second lens component, the reference symbol β T is the magnification of finder on a high magnification side.
Claim 2
Dependent Claim
160 words
A zoom finder comprising, beginning on an object side, a first lens component having positive refractive power, a second lens component having negative refractive power a third lens component having negative refractive power and a fourth lens component having positive refractive power, wherein said Albada system is constructed by said third lens component and said fourth lens component and said zoom finder with an Albada System is arranged to be zoomed by moving said second lens component, and satisfies the following conditions: ##EQU3## where the reference symbol RA is the radius of curvature of a surface of an object side of the fourth lens component, the reference symbol R B is the radius of curvature of a surface of an image side of the fourth lens component, the reference symbol n 2 is the refractive index relative to the D-lines of the second lens component, the reference symbol β T is the magnification of finder on a high magnification side.
Claim 3
Dependent Claim
50 words
A zoom finder with an Albada System according to claim 1, wherein one surface of said first lens component includes an aspherical surface having such contour that a middle portion adjacent to the optical axis has spherical shape and its curvature becomes gentle as it separates from the optical axis.
Claim 4
Dependent Claim
41 words
A zoom finder with an Albada System according to claim 2, wherein, when a distance between principal points of said third lens component and said fourth lens component is H 34 , the following condition is satisfied: 6 mm<H.sub.34 <10 mm.
Claim 5
Dependent Claim
28 words
A zoom finder with an Albada System according to claim 3, further comprising a frame provided on the surface of the object side of said fourth lens component.
Claim 6
Dependent Claim
40 words
A zoom finder with an Albada System according to claim 3, further comprising an optical member arranged in close vicinity to said fourth lens component on the object side of said fourth lens component and provided with a frame thereon.
Claim 7
Dependent Claim
59 words
A zoom finder with an Albada System according to claim 3, further comprising an optical member arranged in close vicinity to said fourth lens component on the object side of said fourth lens component and provided with a field frame thereon, wherein a focusing frame is provided on the surface of the object side of said fourth lens component.
Claim 8
Dependent Claim
33 words
A zoom finder with an Albada System according to claim 1, wherein said first lens component is moved along the optical axis and is connected with the movement of said second lens component.