Canon GL2 Lens

I have a Canon GL2... I love the camera, but am wanating to be able to take video from up to 800 yards and have it be descent.. I had a 8x monocular that I used as a lens for getting far away shots with my previous sony camera it worked great. I bought an adapter ring to fit it to the GL2 but it doesnt work quite as well. The diameter of the lens needs to be larger to match that of the GL2 to be successful in capturing the correct color and light. Any of you know of such a lens?