Wow! I searched through the butterfly images for about 45 minutes before submitting to the ID request. You identified it for me almost immediately. This insect was very cooperative for me, the sun wasn't. I used my body to shade the sunlight and reduce harsh shadows. I used a Canon 100mm macro lens with a close focus diopter.

I've often resorted to a 300mm focal length in pursuit of these beauties. Your photo really shows off the wings; often images of this butterfly look like dark blobs. Now someone reviewing images will have a better example (yours!) to look at.