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Compact, fast zoom lens system

Image Number 5 for United States Patent #5267084.

The present invention provides a zoom lens system comprising, in order from the object side, a first lens unit G1 having a positive refracting power; a second lens unit G2 including a front subunit having at least one negative lens and a rear subunit having at least one negative lens and at least two positive lenses located more closely to the image side than said negative lens and having a positive refracting power as a whole, said front and rear subunits having a positive composite power; and a third lens unit G3 having a negative refracting power; said first, second and third lens units including gaps between them, which are variable for zooming from the wide to tele position. This compact, three-unit zoom lens system has a zoom ratio of about 2 or more but, nonetheless, has a small F-number or is fast

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