This 2x extender is an inexpensive means of doubling the effective focal length of lenses. It works by magnifying the center of the main lens. As such, it reduces light intensity by a factor of four and resolution by a factor of two. And of course it magnifies aberrations in the main lens.
You'll get better images with a lens having the necessary focal length, without use of an extender. If you're not finding the optimal lens, please ask us for a recommendation.