The ornamental design for a variablefocallengthlens, as shown and described.
FIG. 1 is a top front perspective view of a variable focal length lens;
FIG. 2 is a bottom rear perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a right-side view thereof;
FIG. 6 is a left-side view thereof;
FIG. 7 is a top view thereof;
FIG. 8 is a bottom view thereof; and,
FIG. 9 is a top rear perspective view thereof, shown in condition of use with an image pickup device and a microscope disclosed in broken lines to illustrate an environment.
The broken lines depict portions of the variable focal length lens in which the design is embodied that form no part of the claimed design. The broken lines showing an image pickup device and a microscope in FIG. 9 represent environmental structure and form no part of the claimed design.