Patent US3923369A successfully refreshed from Google Patents.
US3923369A
Expired / Lapsed
US
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Retrofocus type of objective lens
Assignee: Minolta Co Ltd
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Filing: 1974-02-27
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Granted: 1975-12-02
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Expires: 1994-02-27
Abstract
Abstract A retrofocus objective lens system has at least two adjoining positive lenses located on the object side, an air spacing which includes a diaphragm and another two adjoining positive lenses located nearest to the image side. The entire lens system is divided into three lens groups (I, II, III) by two air spacings (dA, dB) defined between each two of the two sets of two adjoining positive lenses, whereby the object side first lens group (I) as well as the image side third lens group (III) are moved integrally along an optical axis in cooperation with the focusing operation, while an intermediate second lens group (II) is moved at a speed different from that of the groups (I) and (III), and thereby the air spacings dA and dB are varied so as to compensate for aggravated aberration resulting from focusing to a short distance.
Inventors
- 👤 Akiyoshi Nakamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 09:49
CPC Classifications
G; G02; G02B; G02B13/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
168 words
A retrofocus objective lens comprising a front lens group including a rear positive lens, a rear lens group including a rearmost lens, an intermediate lens group disposed between and axially spaced from said front and rear lens groups including a front positive lens delineating with said front lens group rear positive lens, a first intergroup air space, and a rear positive lens delineating with said rear group rearmost positive lens a second intergroup air space, said intermediate lens group further including a diaphragm disposed at the back of said front lens of the intermediate lens group, the distance between said front and rear lens groups being fixed, and means for concurrently axially moving said front and rear lens groups as a unit and said intermediate lens group at a rate different from that of said front and rear lens groups to thereby vary the axial dimensions of said intergroup air spaces and compensate for the aggravation of aberration attendant to changes in the focus of said objective lens.
Claim 2
Dependent Claim
168 words
A retrofocus objective lens comprising a front lens group including a rear positive lens, a rear lens group including a rearmost lens, an intermediate lens group disposed between and axially spaced from said front and rear lens groups including a front positive lens delineating with said front lens group rear positive lens, a first intergroup air space, and a rear positive lens delineating with said rear group rearmost positive lens a second intergroup air space, said intermediate lens group further including a diaphragm disposed at the back of said front lens of the intermediate lens group, the distance between said front and rear lens groups being fixed, and means for concurrently axially moving said front and rear lens groups as a unit and said intermediate lens group at a rate different from that of said front and rear lens groups to thereby vary the axial dimensions of said intergroup air spaces and compensate for the aggravation of aberration attendant to changes in the focus of said objective lens.
Claim 3
Dependent Claim
86 words
A retrofocus type objective lens system as set forth in claim 1, wherein said system consists of 10 lenses as shown by following table in which the focal length ''''f'''' of the entire system is 1, said first air space being that defined between a fourth positive lens and a fifth positive lens, said second air space being that defined between a ninth positive lens and a 10th positive lens, relative aperture being F/2.0, angle of view being 72* and backfocus being 1.31f (f: focal length):
Claim 4
Dependent Claim
30 words
The objective lens of claim 1 including means for axially moving said intermediate lens group relative to and independent of the axial movement of said front and rear lens groups.
Claim 5
Dependent Claim
50 words
The objective lens of claim 3 wherein the front lens group includes four lenses, the intermediate lens group includes five lenses and the rear lens group includes one lens, the first, third, sixth and eigth lenses being negative and the second, fourth, fifth, seventh, ninth and 10th lenses being positive.
Claim 6
Dependent Claim
15 words
The objective lens of claim 4 wherein the fifth and sixth lenses form a doublet.
Claim 7
Dependent Claim
164 words
A retrofocus type objective lens system comprising: a diaphragm; a first pair of adjoining positive lenses with a first variable air space therebetween and disposed in front of said diaphragm; a second pair of adjoining positive lenses with a second variable air spaced therebetween and disposed at the rearmost of the lens system, said first and second air spaces separating the lens system into front and intermediate lens groups and a rearmost lens; means for moving said front lens group and said rearmost lens along the optical axis of the lens system while maintaining the relative distance therebetween constant; and means for moving said intermediate lens group with the movement of said front lens group and said rearmost lens at a rate different from that of said front lens group and said rearmost lens, whereby the axial dimension of said first and second air spaces varies to compensate for the aggravation of aberration attendant to the change in focusing of said objective lens system.
Claim 8
Dependent Claim
164 words
A retrofocus type objective lens system comprising: a diaphragm; a first pair of adjoining positive lenses with a first variable air space therebetween and disposed in front of said diaphragm; a second pair of adjoining positive lenses with a second variable air spaced therebetween and disposed at the rearmost of the lens system, said first and second air spaces separating the lens system into front and intermediate lens groups and a rearmost lens; means for moving said front lens group and said rearmost lens along the optical axis of the lens system while maintaining the relative distance therebetween constant; and means for moving said intermediate lens group with the movement of said front lens group and said rearmost lens at a rate different from that of said front lens group and said rearmost lens, whereby the axial dimension of said first and second air spaces varies to compensate for the aggravation of aberration attendant to the change in focusing of said objective lens system.
Claim 9
Dependent Claim
30 words
A retrofocus type objective lens system as in claim 6 further comprising means for manually moving said intermediate lens group independently of said front lens group and said rearmost lens.
Claim 10
Dependent Claim
71 words
A retrofocus type objective lens system as set forth in claim 6, wherein said system consists of the following 10 lenses, said first air space being that defined between a fourth positive lens and a fifth positive lens, said second air space being that defined between a ninth positive lens and a tenth positive lens, relative aperture being F/2.0, angle of view being 72* and backfocus being 1.31f (F: focal length):
References Cited (Backward Citations)
US3330615A
Cited
US3748022A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-01 | 1979-06-02 | 1979-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-01 | 1983-06-02 | 1983-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-01 | 1987-06-02 | 1987-12-02 | $7700.00 | Window Closed / Lapsed |