ZOOM LENS, OPTICAL APPARATUS AND ZOOM LENS MANUFACTURING METHOD Russian patent published in 2016 - IPC G02B15/173 G02B15/20 

FIELD: photography.

SUBSTANCE: zoom lens comprises first, third and fourth positive lens groups and a second negative lens group. First, second and third lens groups when scaling images move along an optical axis and following expressions are satisfied: 8.00 < β2T/β2W < 12.00, 2.00 < β3T/β3W < 5.00, where β2T and β3T are transverse magnification in second and third lens groups in final state of telescopic lens, β2W and β3W are transverse magnification in second and third lens groups in final state wide-angle lens. First lens group includes, in order from object, a negative lens and a positive lens and following expression is satisfied: 0.00 < (-f1c)/f1 < 250.00, where f1c is composite focal distance of said negative and positive lenses, f1 is focal distance of first lens group.

EFFECT: technical result is increase in scaling factor at small size, high image quality and high magnification.

11 cl, 24 dwg, 4 tbl