Newborn baboon

This is a one day old baby baboon who was being cuddled by its mother about 8 feet from my safari vehicle. If I used a 70-200mm zoom, I couldn't fill the frame with the two animals. They were sitting on the ground, and I didn't want too much dirt in the composition. At the time, I also had a Canon 500mm f/4 telephoto, but the problem with that lens is I couldn't focus to 8 feet. The minimum focusing distance on that lens is 14.5 feet. So, I placed an extension tube between the 500mm lens and the camera body. These tubes are just hollow spacers -- no glass -- but they instantly shorten the minimum focusing distance. Now I was able to fill the frame with the baboons plus focus sharply on them. My settings were 1/320, f/4.5, and 200 ISO. Considering the shallow depth of field, I was lucky that the mother and the baby were on the same plane.