I always carry one or two extension tubes with me no matter where I travel. When placed between the camera body and the lens, these hollow tubes (I own the Kenko set of 3 tubes) allow any lens to focus closer than its minimum focus distance. I took this picture of an agama lizard in Namibia, and I used a 500mm telephoto because a close approach would have scared the reptile away. The minimum focus distance of the lens is about 14 feet, but with one extension tube, I was able to focus from just 8 feet away. No light is lost, and although there is depth of field loss, this is true any time an image is magnified. When one or more extension tues are used, you can no longer focus to infinity. I used a tripod to stabilize the lens, and my settings were 1/60, f/14, 1000 ISO.