Each summer, for about 2 months, the Sweetbriar Nature Center opens it's Butterfly Vivarium. I always thoroughly enjoy shooting in there. It's peaceful, beautiful, and the butterflies will literally land on me. They also have a nice garden with an abundance of flowers and plants. In addition, they rehabilitate injured birds of prey along with various other animals. All of this amazing stuff for a mere three bucks!
A few years ago I bought the Canon 100mm f2.8 Macro lens specifically for this place. The 1:1 ratio allows me to fill the frame with tiny details. This is one sharp lens, and it's fairly priced too. Although it has a fast aperture, the trick with shooting butterflies is not to use too shallow of a depth of field. At f2.8 only a portion of the subject will be in focus. I prefer to have the entire butterfly as sharp as possible.
These days, I like to use an aperture of at least f8 when shooting in the Vivarium. This solves the sharpness problem, but it creates another issue that needs to be solved. The background. Ideally, you want your butterfly to stand out against the background. How do you do this when everything is in focus at f8? There are a few tricks. First, you can use an external flash with the power dialed down a bit to illuminate your butterfly, while allowing the background to go dark. You can also try to find a subject where you have a few feet of separation between it, and the background. I've listed the camera setting for each shot below it. I plan on returning to this excellent place again soon. If you have some nice butterfly tips of your own, please feel free to leave them in the comments section. Thanks!