The one weekend we visited San Diego, it decided to rain (probably filling SD's yearly quota). Due to this, the SD Zoo was essentially empty! Wife and I, not being afraid of a little rain on account of being from the East (best) Coast, had a grand old time exploring the exhibits and getting unobstructed views of the various wildlife throughout. I'm aware that it's generally frowned upon to showcase wildlife in a Zoo environment, but at least I'm being honest about this composition.
This was taken with my Sigma 150mm f/2.8 macro, which far exceeded my expectations in these conditions (moving subject).
