Hi, I am a semi-pro photographer and am interested in purchasing a extender tube for use with my Canon 70-200 IS USM 2.8 and my Canon 7D. I am looking at this primarily for personal use and not for my professional work. More specifically, I am looking to use it to do wildlife photography at my cabin (relatively bright conditions). I haven't used an extender tube since my days in film and was wondering if anybody had any experience with either of these tubes. I am also interested in any other thoughts anybody might have on the topic. Thanks in advance!