I got a D3100 and a used Nikon ED AF-S 80-200mm lens. I am going to be using it for video and am concerned about tripod mounting the camera with this huge lens hanging off the end. I was wondering if someone could direct me to a tripod mount that I could attach to this lense. It looks like the lens has a groove towards the back that was designed for such a purpose. Maybe it originally came with one, but since I got it used who knows.