Compact high-performance zoom lens

A zoom lens comprising, objectwise to imagewise:

• first, second, third, and fourth lens groups having positive, negative, negative, and positive refractive power, respectively, disposed on an optical axis;
• the first lens group having a focal length f.sub.1 and including, sequentially objectwise to imagewise, a negative lens eIement and first, second, and third positive lens elements;
• the zoom lens being operable to zoom over a zoom ratio V from a wide-angle end to a telephoto end, at which wide-angle end the second lens group has a lateral magnification .beta..sub.2W and at which telephoto end the zoom lens has a focal length f.sub.T and an F-number F.sub.T, wherein, during zooming from the wide-angle end to the telephoto end, the second lens group moves linearly objectwise to imagewise on the optical axis, the third lens group moves on the optical axis, and the first and fourth lens groups remain stationary on the optical axis;
• the zoom lens satisfying the conditions:
• 0.6<F.sub.T.sup.1/2 (f.sub.1 /f.sub.T)<1.0
• 0.7<.vertline..beta..sub.2W .multidot.V.sup.1/2 <1.1;
• and
• the third lens group being operable to move, during zooming from the wide-angle end to the telephoto end, first imagewise then objectwise.

A zoom lens comprising, objectwise to imagewise:

• first, second, third, and fourth lens groups having positive, negative, negative, and positive refractive power, respectively, disposed on an optical axis;
• the first lens group having a focal length f.sub.1 and including, sequentially objectwise to imagewise, a negative lens element and first, second, and third positive lens elements;
• the fourth lens group comprising an objectwise lens subgroup and an imagewise lens subgroup,
• each of the objectwise and imagewise lens subgroups having a positive refractive power;
• the objectwise lens subgroup comprising, objectwise to imagewise, three positive lens elements and a negative lens element;
• the zoom lens being operable to zoom over a zoom ratio V from a wide-angle end to a telephoto end, at which wide-angle end the second lens group has a lateral magnification .beta..sub.2W and at which telephoto end the zoom lens has a focal length f.sub.T and an F-number F.sub.T, wherein, during zooming from the wide-angle end to the telephoto end, the second lens group moves linearly objectwise to imagewise on the optical axis, the third lens group moves on the optical axis, and the first and fourth lens groups remain stationary on the optical axis;
• the zoom lens satisfying the conditions:
• 0. 6<F.sub.T.sup.1/2 (f.sub.1 /f.sub.T)<1.0
• 0.7<.vertline..beta..sub.2W .multidot.V.sup.1/2 .vertline.<1.1;
• and
• wherein the imagewise lens subgroup comprises, objectwise to imagewise, a positive lens element, first, second, and third compound lenses, and a negative lens element.

A zoom lens comprising, objectwise to imagewise:

• first, second, third, and fourth lens groups having positive, negative, negative, and positive refractive power, respectively, disposed on an optical axis;
• the first lens group having a focal length f.sub.1 and including, sequentially objectwise to imagewise, a negative lens element and first, second, and third positive lens elements;
• the zoom lens being operable to zoom over a zoom ratio V from a wide-angle end to a telephoto end, at which wide-angle end the second lens group has a lateral magnification .beta..sub.2W and at which telephoto end the zoom lens has a focal length f.sub.T and an F-number F.sub.T, wherein, during zooming from the wide-angle end to the telephoto end, the second lens group moves linearly objectwise to imagewise on the optical axis, the third lens group moves on the optical axis, and the first and fourth lens groups remain stationary on the optical axis;
• the zoom lens satisfying the conditions:
• 0.6<F.sub.T.sup.1/2)f.sub.1 /f.sub.T)<1/0
• 0.7<.vertline..beta..sub.2W .multidot.V.sup.1/2 .vertline.<1.1;
• wherein the third lens group moves, during zooming from the wide-angle end to the telephoto end, first imagewise then objectwise;
• and
• wherein the third lens group comprises a compound lens including, objectwise to imagewise, a biconcave lens element and a biconvex lens element.

A zoom lens comprising, objectwise to imagewise:

• first, second, third, and fourth lens groups having positive, negative, negative, and positive refractive power, respectively, disposed on an optical axis;
• the second lens group comprising at least four lens components;
• the first lens group having a focal length f.sub.1 and comprising, sequentially objectwise to imagewise, a negative lens element and first, second, and third positive lens elements, the negative lens element having an objectwise surface having a radius of curvature R.sub.1 and an imagewise surface having a radius of curvature R.sub.2 ;
• the zoom lens being operable to zoom over a zoom ratio V from a wide-angle end to a telephoto end, at which wide-angle end the second lens group has a lateral magnification .beta..sub.2W and at which telephoto end the zoom lens has a focal length f.sub.T and an F-number F.sub.T, wherein, during zooming from the wide-angle end to the telephoto end, the second lens group moves linearly objectwise to imagewise on the optical axis, the third lens group moves on the optical axis, and the first and fourth lens groups remain stationary on the optical axis;
• and
• the zoom lens satisfying the conditions:
• 0.6<F.sub.T.sup.1/2 (f.sub.1 /f.sub.T)<1.0
• 0.7<.vertline..beta..sub.2W .multidot.V.sup.1/2 .vertline.<1.1
• -1.4<(R.sub.2 +R.sub.1)/(R.sub.2 -R.sub.1)<-1.2.