There was a book signing in the evening at the Saint Louis Zoo, and the grounds were open after hours.
The sun was setting as we arrived, and we took a quick walk as the light was fading.
I had the Pentax *ist D digital SLR with me, and left the f/4.5 zoom lens, 18 - 55mm, mounted.
It was so dark, I shot wide open, at first with the ASA setting bumped up to 1600, then eventually pushed all the way to ASA 3200. Even so, shutter speeds were between 1/4 second and 1/30 for the fastest.
I have a steady hand, these were hand held, no tripod. Light was from the glow of the sky, no flash, no supplemental lighting.
There was another guy out there, using a flash, and I could see that he was spooking the animals.
With the conditions, I think I did just fine.

Please click on thumbnails to see enlarged.
All images are Copyright 2009 E.J.Kowalski.