I recently became interested in the challenge of photographing these delicate creatures after a few brief attempts in my backyard. I learned of the Magic Butterfly House at the NC Museum of Life & Science, in Durham, NC (about a 2 hour drive from my home), and spent some time there the last two Saturdays in August. The first trip was a good learning experience, not yielding many "keepers" but better preparing me for the next time.
Because of the need for reasonable working distances, and the desire for fairly close-up type shots, I used the Canon 100-400L lens as a starting point. It's minimum focus distance is almost 6 feet, however, which is too long to get decent magnification. So I added some extension (Kenko tubes, 32 mm the first trip, 20 mm the second trip) which reduced the focus distance to around 3 to 4 feet. The first trip I also used the Canon 1.4x II teleconverter to increase magnification, but combined with the light loss from 32 mm of extension, I had problems with sufficient depth of field and shutter speed. Of necessity, I also used the 550EX flash, but wanted to maintain as much natural light as possible. Because the flash was not on the D30's hot shoe, I also needed to use the ST-E2 to trigger it remotely.
This equipment is heavy, and a tripod would be too cumbersome and slow to set up for shooting butterflies, so I opted to use a monopod (Bogen-Manfrotto Carbon Fiber 449). I used the Arca-Swiss B1 ballhead the first week, and this worked reasonably well. But the second week I also put on the Wimberley Sidekick and this combination worked extremely well: fairly light and portable, but very stable and maneuverable. I attached the 550EX flash to the Wimberley Combo 2 Bracket, and this also worked well, giving me the potential to quickly switch from landscape to portrait orientation and still have the flash overhead. I've included a photo of the setup taken with my daughter's Canon S10. Without larger shots, from multiple angles, it's tough to show everything in detail, but this will give a general idea of how it looked all assembled.
If you ever plan on visiting and shooting at a Butterfly House, keep in mind that the heat and humidity are typically very high. In my first visit, I had to wait about 20 minutes, sweltering and sweating, until my equipment warmed up enough to not fog up. The second time I kept my car fairly warm during the drive there, and was able to avoid this problem. I also dressed lighter, had a towel on my belt, and brought a change of clothes - this all made for a more comfortable and productive trip.
I've done my best to identify the butterflies featured here, but have not been completely successful in this regard. If I've erred in ones I've tentatively identified, or if you know what species the unidentified ones are, please email me.