I possess perhaps the minimal equipment required to take decent butterfly photographs and the tips below are keyed to that. You can certainly do better if you can spend a little more!

First you need an SLR camera. I have a Pentax K1000 -- the most basic of the lot. With this camera I have to decide everything for myself, though at least it has a simple light meter. I like this because it makes me think about every shot, but you could work faster with a more automated camera and be able to take some pictures which I miss.

For the lens you need something with decent magnification and the ability to focus on nearby objects. I use an Albinar 80-200mm zoom with a "macro" setting -- which means one can twist the lens to move the glass away from the camera body, thus enabling one to focus on objects which are about a couple of feet away (as opposed to a minimum focussing distance of 6 feet in the normal setting). For most butterflies this combination of magnification and focussing distance is still too weak, so I use Vivitar extension tubes to improve the latter. An extension tube is merely a hollow tube which fits between the camera and the lens. Again, by increasing the distance between the lens and the film it enables focussing on closer objects.

So far I have avoided using flash, except for some moths taken at night. Some people are said to avoid it for aesthetic or ethical reasons. My reason so far is that the flash unit makes the setup bulkier and harder to handle. But many butterflies can only be photographed in dark places -- inside bushes or in foliage, and it is hard to imagine doing much of that without resorting to the use of a flash.

The personal equipment I have listed above cost me about $300, though some of it was bought secondhand. What are the directions in which more expensive equipment could improve results? A camera where you do not have to set the aperture and speed independently would increase the speed at which you work. I used to own a Pentax ME with aperture priority (aperture decides speed) and found it useful. What is important in this case is to have the ability to over or under expose ("compensate") by some amount to take care of situations where the lighting is uneven. The ME allowed upto one full stop of compensation, and this was always sufficient in my experience. A fully programmed camera may not be particularly advantageous for chasing butterflies -- you will certainly need to think about depth of field and hand shake and control the camera settings to take care of them. The other feature which is relevant is auto-focussing. Again, by increasing the speed at which you can act it will enable you to take pictures which would be otherwise impossible. On the other hand some pictures require precise focussing decisions which are easy to make when the focussing is manual. Now one can always decide to use an automatic camera in a manual mode but it may not be designed for this to be convenient.

As for the lens, apart from the cheap option of a 200mm zoom + extension tubes, what one hears being recommended is a "proper" 100mm macro lens. This means the lens itself can close focus without needing the crutch of extension tubes. Results are said to be much sharper than the first option. (For comparison Pentax lists its 80-200mm f/4.7-5.6 zoom which can focus at 3.4 feet at $462, and a 100mm f/3.5 macro with a minimum focussing distance of 1.4 feet at $340. They are advertised on the web for about $140 and $210 respectively!)

So much for the equipment. Now we have to find the butterflies. Any green patch should have some, though your chances improve if it is not too manicured and if it has some weeds. You need to find them at the right time too. They should be slightly mobile so you can spot them but not so active that you don't have time to approach them. So the best time to catch them is in the morning, about an hour or two after sunrise.

Having spotted a butterfly, approach it slowly and smoothly, avoiding any sudden moves. Keep a low profile -- crawling may be necessary sometimes. The closer you get the slower and more restricted your movements should become. Avoid having your shadow fall on the butterfly (this can be difficult). Be aware that the insect is likely to fly off the very instant before you press the shutter release. To improve your chances make sure the shutter and aperture settings are approximately correct before you get very close to the butterfly -- this will reduce the fiddling at the crucial moments.