Fish eye lens system

• US 4,009,943 A
• Filed: 08/20/1975
• Issued: 03/01/1977
• Est. Priority Date: 09/05/1974
• Status: Expired due to Term

• Current Assignee: Minolta Camera Kabushiki Kaisha
• Original Assignee: Minolta Camera Kabushiki Kaisha
• Inventors: Horimoto, Mitsuaki
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Clark, Conrad
• Application Number:
  US05/606,123
• Time in Patent Office: 559 Days
• Field of Search: 350/214, 350/215, 350/207
• US Class Current: 359/723
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces

Abstract

An extremely wide angle or fish eye lens system is provided capable of compensating for lateral chromatic aberration, field curvature and astigmatism while providing an aperture ratio of F/4 for use with a compact single lens reflex camera. The fish eye lens system includes a first lens group of four lenses on the object side of a diaphragm and a second lens group of at least three lenses on the image side of the diaphragm. From the object to image side, the first lens group includes a pair of negative lenses, a cemented doublet and a positive fourth lens having a convex surface on the image side adjacent a concave surface of the cemented doublet. The second lens group includes a pair of cemented doublets as two of the three lenses.

Claims

1. A fish eye lens system having a diaphragm on its optical axis and an object and image side to the lens system comprising:

a first lens group positioned on the object side of the diaphragm including a first negative meniscus lens having a convex surface on the object side, a second negative meniscus lens having a convex surface on the object side, a third negative doublet lens having a concave surface on the image side and a fourth positive lens having a convex surface on the object side, the concave surface of the third lens and the convex surface of the fourth lens forming a space of positive meniscus shape therebetween; and

a second lens group positioned on the image side of the diaphragm including at least three lenses of which two of the lenses are doublets composed of positive and negative components.

2. A lens system as defined in claim 1 further including a filter member movable between two positions on and off the optical axis of the lens system.

3. A lens system as defined in claim 1 wherein the fourth lens is a cemented doublet.

4. A lens system as defined in claim 1 wherein the fifth and seventh lenses are cemented doublets.

5. A lens system as defined in claim 1 wherein the fifth, sixth and seventh lenses are cemented doublets.

6. A lens system as defined in claim 1 wherein the fifth and sixth lenses are cemented doublets.

7. A lens system as defined in claim 1 having design parameters within the following ranges:

##EQU3##wherein r₇ and r₈ represent respectively the radii of curvature of the concave surface of the third lens and convex surface of the fourth lens, R represents the radii of curvature for the intermediate surfaces of all of the cemented doublets in the second lens group, Np represents the average refractive index for all the positive components of all of the cemented doublets in the second lens group, Nn represents the average refractive index for all the negative components of all of the cemented doublets in the second lens group, Vp represents an average Abbe'"'"'s Number for all the positive components of all of the cemented doublets in the second lens group, Vn represents an average Abbe'"'"'s Number for all the negative components of all of the cemented doublets in the second lens group, and f represents the total focal length of the lens system.

8. A lens system as defined in claim 1 having design parameters within the following ranges:

##EQU4##wherein r₇ and r₈ represent respectively the radii of curvature of said concave surface of the third lens and said convex surface of the fourth lens.

9. A lens system as defined in claim 1 having design parameters within the following ranges:

##EQU5##wherein R represents the radii of curvature for the intermediate surfaces of all of the cemented doublets in the second lens group, Np represents the average refractive index for all the positive components of all of the cemented doublets in the second lens group, Nn represents the refractive index for all the negative components of all of the cemented doublets in the second lens group, Vp represents an average Abbe'"'"'s Number for all the positive components of all of the cemented doublets in the second lens group, Vn represents an average Abbe'"'"'s Number for all the negative components of all of the cemented doublets in the second lens group and f represents the total focal length of the lens system.

10. In a fish eye lens system having a field angle of approximately 180°

, the improvement comprising;

a first lens group having at least three negative lenses and a fourth positive lens;

a second lens group including at least a pair of doublets with positive and negative components, and a diaphragm positioned between the first and second lens groups, the lens system complying with the following parameters;

##EQU6##wherein R represents the radii of curvature for the intermediate surfaces of all of the cemented doublets in the second lens group, Np represents the average refractive index for all the positive components of all of the cemented doublets in the second lens group, Nn represents the average refractive index for all of the negative components of all of the cemented doublets in the second lens group, Vp represents an average Abbe'"'"'s Number for all the positive components of all of the cemented doublets in the second lens group, Vn represents an average Abbe'"'"'s Number for all the negative components of all of the cemented doublets in the second lens group and f represents the total focal length of the lens system.

11. The invention of claim 10 further including an additional design parameter, as follows;

##EQU7##wherein r₇ and r₈ represent respectively, the radii of curvature of the concave surface of the third lens and the convex surface of the fourth lens in the first lens group.

12. The invention of claim 11 the fourth lens of the first group is a doublet.

13. The invention of claim 11 wherein the second lens group includes three lenses and the fifth and seventh lenses are doublets.

14. The invention of claim 11 wherein the second lens group includes three lenses and the fifth, sixth and seventh lenses are doublets.

15. The invention of claim 11 wherein the second lens groups includes three lenses and the fifth and sixth lenses are doublets.

16. A fish eye lens system comprising the following design parameters:

space="preserve" listing-type="tabular">______________________________________ f = 1 F/4 field angle 2ω

= 180°

back focal length s'"'"' = ______________________________________ 4.8 Length on Refractive Index/ Radius of Curvature Axis Abbe'"'"'s No. ______________________________________ ##STR25## d.sub.1 = 0.3118 N.sub.1 /V.sub.1 = 1.6204/60.3 d.sub.2 = 1.8 ##STR26## d.sub.3 = 0.26 N.sub.2 /V.sub.2 = 1.713/53.9 d.sub.4 = 1.0 ##STR27## d.sub.5 = 1.0 d.sub.6 = 0.14 N.sub.3 /V.sub.3 = 1.5934/34.8 N.sub.4 /V.sub.4 = 1.72/50.2 d.sub.7 = 0.0543 ##STR28## d.sub.8 = 0.14 d.sub.9 = 0.5 N.sub.5 /V.sub.5 = 1.5890/53.3 N.sub.6 /V.sub.6 = 1.5955/39.4 d.sub.10 = 0.2 ##STR29## d.sub.11 = 0.2 N.sub.7 /V.sub.7 = 1.5186/60.1 d.sub.12 = 0.5553 ##STR30## d.sub.13 = 0.16 d.sub.14 = 0.5175 N.sub.8 /V.sub.8 = 1.883/41.0 N.sub.9 /V.sub.9 = 1.5112/51.0 d.sub.15 = 0.3823 ##STR31## d.sub.16 = 0.3620 N.sub.10 /V.sub.10 = 1.4645/65.9 d.sub.17 = 0.0484 ##STR32## d.sub.18 = 0.2 d.sub.19 = 0.9 N.sub.11 /V.sub.11 = 1.7847/25.7 N.sub.12 /V.sub.12 = 1.4787/58.7 ______________________________________

17. A fish eye lens system comprising the following design parameters:

space="preserve" listing-type="tabular">______________________________________ f = 1 F/4 field angle 2ω

= 180°

back focal length s'"'"' = ______________________________________ 4.82 Length on Refractive Index/ Radius of Curvature Axis Abbe'"'"'s No. ______________________________________ ##STR33## d.sub.1 = 0.3004 N.sub.1 /V.sub.1 = 1.6204/60.3 d.sub.2 = 1.8 ##STR34## d.sub.3 = 0.26 N.sub.2 /V.sub.2 = 1.713/53.9 d.sub.4 = 1.0 ##STR35## d.sub.5 = 1.0 d.sub.6 = 0.3 N.sub.3 /V.sub.3 = 1.5934/34.8 N.sub.4 /V.sub.4 = 1.713/54.0 d.sub.7 = 0.1885 ##STR36## d.sub.8 = 0.4757 N.sub.5 /V.sub.5 = 1.5934/34.8 d.sub.9 = 0.2 ##STR37## d.sub.10 = 0.2 N.sub.6 /V.sub.6 = 1.5186/60.1 d.sub.11 = 0.5553 ##STR38## d.sub.12 = 0.16 d.sub.13 = 0.8103 N.sub.7 /V.sub.7 = 1.805/41.0 N.sub.8 /V.sub.8 = 1.5317/48.9 d.sub.14 = 0.02 ##STR39## d.sub.15 = 0.6010 d.sub.16 = 0.2 N.sub.9 /V.sub.9 = 1.4645/65.9 N.sub.10 /V.sub.10 = 1.7847/25.7 d.sub.17 = 0.5 ##STR40## d.sub.18 = 0.15 d.sub.19 = 1.14 N.sub.11 /V.sub.11 = 1.717/47.9 N.sub.12 /V.sub.12 = 1.4707/67.4 ______________________________________

18. A fish eye lens system comprising the following design parameters:

space="preserve" listing-type="tabular">______________________________________ f = 1 F/4 field angle 2ω

= 180°

back focal length s'"'"' = ______________________________________ 4.82 Length on Refractive Index/ Radius of Curvature Axis Abbe'"'"'s No. ______________________________________ ##STR41## d.sub.1 = 0.3118 N.sub.1 /V.sub.1 = 1.6204/60.3 d.sub.2 = 1.8 ##STR42## d.sub.3 = 0.26 N.sub.2 /V.sub.2 = 1.713/53.9 d.sub.4 = 1.0 ##STR43## d.sub.5 = 1.0 d.sub.6 = 0.14 N.sub.3 /V.sub.3 = 1.5934/34.8 N.sub.4 /V.sub.4 = 1.713/54.0 d.sub.7 = 0.0987 ##STR44## d.sub.8 = 0.14 d.sub.9 = 0.5 N.sub.5 /V.sub.5 = 1.5891/61.1 N.sub.6 /V.sub.6 = 1.5934/34.8 d.sub.10 = 0.2 ##STR45## d.sub.11 = 0.2 N.sub.7 /V.sub.7 = 1.5186/60.1 d.sub.12 = 0.5553 ##STR46## d.sub.13 = 0.16 d.sub.14 = 0.4907 N.sub.8 /V.sub.8 = 1.8835/40.3 N.sub.9 /V.sub.9 = 1.4875/70.1 d.sub.15 = 0.02 ##STR47## d.sub.16 = 0.4342 d.sub.17 = 0.1069 N.sub.10 /V.sub.10 = 1.4875/70.1 N.sub.11 /V.sub.11 = 1.7847/25.7 d.sub.18 = 0.0430 ##STR48## d.sub.19 = 0.7058 N.sub.12 /V.sub.12 = 1.4645/65.9 ______________________________________