JPS6452112A - Compact zoom lens with large aperture ratio - Google Patents
Compact zoom lens with large aperture ratioInfo
- Publication number
- JPS6452112A JPS6452112A JP20850887A JP20850887A JPS6452112A JP S6452112 A JPS6452112 A JP S6452112A JP 20850887 A JP20850887 A JP 20850887A JP 20850887 A JP20850887 A JP 20850887A JP S6452112 A JPS6452112 A JP S6452112A
- Authority
- JP
- Japan
- Prior art keywords
- group
- negative
- positive
- ratio
- refractive indexes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Lenses (AREA)
Abstract
PURPOSE:To shorten the overall length of the zoom lens consisting of a 1st group with a negative refractive index and 2nd and 3rd groups with positive refractive indexes by setting the refractive indexes, focal lengths, etc., of the 1st and 2nd groups within specific ranges. CONSTITUTION:The room lens consisting of the 1st group consisting of two negative lens elements, the 2nd group consisting of two positive lens elements, and the 3rd group, and the 1st group and 2nd group are moved at the time of zooming. Further, the ratio of the refractive indexes phiI and phiII of the 1st and 2nd groups, the ratio of the refractive index phiI of the 1st group and the composite focal length fW of the whole system on the wide-angle end, the ratio of the focal lengths fZP and fZR of the two positive lens elements of the 2nd group, and the ratio of the mean Abbe numbers of the two positive lenses and two negative lenses constituting cemented lenses of the 2nd group are set within specific ranges. Thus, the negative,negative, and positive constitution is employed and the refractive indexes, focal lengths, and Abbe numbers are set within the specific ranges, so variable power of 3 times and a F number of >=1.0 are realized and the overall length of the lens is shortened to reduce the weight.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP20850887A JPS6452112A (en) | 1987-08-22 | 1987-08-22 | Compact zoom lens with large aperture ratio |
US07/230,173 US5009491A (en) | 1987-08-07 | 1988-08-08 | Compact zoom lens system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP20850887A JPS6452112A (en) | 1987-08-22 | 1987-08-22 | Compact zoom lens with large aperture ratio |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS6452112A true JPS6452112A (en) | 1989-02-28 |
Family
ID=16557320
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP20850887A Pending JPS6452112A (en) | 1987-08-07 | 1987-08-22 | Compact zoom lens with large aperture ratio |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6452112A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008070519A (en) * | 2006-09-13 | 2008-03-27 | Canon Inc | Zoom lens and imaging apparatus having the same |
-
1987
- 1987-08-22 JP JP20850887A patent/JPS6452112A/en active Pending
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008070519A (en) * | 2006-09-13 | 2008-03-27 | Canon Inc | Zoom lens and imaging apparatus having the same |
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