I have sold my venerable Canon XTi. I thought initially that it would be a great back up camera, and allow me to have more options when on a shoot with out switching lenses. Well it was not so. I was using it less and less, and when taking it along on a trip, I found it very cumbersome to carry two cameras, plus a tripod and a back pack. So, my XTi is no more. Instead I got myself a Canon 2x Extender. Now you have to understand that this is not made for all lenses. It only works with my Canon 100-400mm zoom lens. My Canon 24-70 and 17-40, won't even install on this. Also I found that the rumors of loosing auto-focus are true. When the extender is installed on the 100-400 lens, it will not auto focus, although the Image Stabilization of the lens still works. Also the lens looses about 4 stops of aperture. So from a 5.6 at 400 mm it becomes 9.6 at 800 mm. A tripod or good light is necessary. Here is an example of what this extender can do. The first picture was taken from the upper terminal station of Jasper Gondola on Whistler mountain. It was taken at 70 mm. The second photo is at 400 mm with the extender, meaning 800 mm. Pretty impressive zoom I must say.