Compact wide angle lens
AssigneeVivitar Corporation
InventorMelvyn H. Kreitzer
Life of this patent
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Abstract
A very compact lens of the retrofocus type, capable of covering a field angle of up to 63.degree., comprising six elements including a singlet front group of strong negative power, and having extremely good aberrational correction.
Claims5
A retrofocus lens consisting of six elements from the object end, a first negative meniscus convex to the object, second and third positive elements, a fourth biconcave element, a fifth positive meniscus concave to the object and a sixth positive element where
- 0.8 f.sub.o >.vertline.f.sub.1 .vertline.>0.6 f.sub.o and
- 0.55 f.sub.o >f.sub.2 >0.5 f.sub.o
- where
- f.sub.1 is the equivalent focal length (EFL) of the first element,
- f.sub.2 is the equivalent focal length (EFL) of the second and third elements,
- f.sub.o is the EFL of the lens.
A retrofocus lens comprising three groups of negative, positive and negative power from the object end, said first group comprising a negative meniscus convex to the object end having an equivalent focal length whose absolute value is between 0.6 and 0.8 of the equivalent focal length of the overall lens, said second group having an equivalent focal length between 0.5 and 0.55 of the equivalent focal length of the overall lens.
Dependencies are inferred from the claim text.