ZOOM LENS
PROBLEM TO BE SOLVED: To provide a zoom lens which has long back focus and also has distortion compensated excellently as a zoom lens consisting of four groups by making a 3rd group and its meniscus lens meet specific requirements. SOLUTION: This lens comprises a 1st group Gr1 having negative refrac...
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| Format: | Patent |
| Sprache: | eng |
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| Zusammenfassung: | PROBLEM TO BE SOLVED: To provide a zoom lens which has long back focus and also has distortion compensated excellently as a zoom lens consisting of four groups by making a 3rd group and its meniscus lens meet specific requirements. SOLUTION: This lens comprises a 1st group Gr1 having negative refracting power, a 2nd group Gr2 having positive refracting power, the 3rd group Gr3 having negative refracting power, and a 4th group Gr4 having positive refracting power in order from the enlargement side. The 3rd group Gr3 comprises a positive meniscus lens M which has its convex surface on the magnification side and a biconcave negative lens in order from the enlargement side. The 3rd group Gr3 and meniscus lens M meet the conditions of 0.30 |
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