PURPOSE: To attain a lens for 35mm camera which has f=300W400mm, F2W2.8, and less variation of aberrations without a floating mechanism, by satisfying prescribed conditions in a focusing telephoto lens which consits of three groups, namely, positive, negative, and positive groups and is focused by movement of the thrid negative group.

CONSTITUTION: The telephoto lens consists of the first convergent lens group G1, a divergent lens group G2, and the second convergent lens group G3 which are arranged in order from the object side, and the first convergent lens group G1 and the divergent lens group G2 form an afocal system, and the divergent lens group G2 is moved to the image side to focus the telephoto lens from an object in the infinity to an object at a short distance. Condition 0.01<d4/f1<0.09 is satisfied when the second air interval of the first convergent lens group is denoted as d4 and the focal length of this group is denoted as f1, and it is desirable that the negative lens component in the object side is an achromatic component with respect to the divergent lens group.