About my Equipment
In my humble opinion, you don't necessarily need an expensive or specialized camera to take photographs of butterflies. Many of today's compact digital cameras are capable of capturing remarkably good closeup images. That said, I've been using an SLR with a macro lens pretty much from the start.
As far as brands go, I shoot Pentax. (Not surprisingly, every photographer is going to tell you that the brand they use is the best.)
Back when I was shooting film, I was using an old 70's era 100mm macro lens on a couple of different SLR bodies ( chiefly the MX ). It was strictly manual focus and manual exposure control. For smaller butterflies, I'd sometimes add an extension tube for extra magnification. One or two images on this website are scans of shots from this period.