A quick initial walk through the zoo will show you which are the best exhibits and which species the most photogenic. Look for direct, natural light and a lack of bars. Stick with exhibits that have foliage, actual rock formations (not poured concrete), and landscaping consistent with the animal's original habitat. Beware of scratched windows, clutter, and evidence of captivity: toys, rope, and worn paths. And avoid exhibits that require a wide-angle lens, introduce artificial light, or show cement.