I realize that the title of your first book is a pun on "Camera obscura" which is really clever. But the only meaning I can find for khamra is in an article on sufism where it's defined as "spiritual drunkenness." Am I on the right track here?

You are indeed! "Khamra" is an Arabic word that means "wine" and is used by Sufi poets as a metaphor in the ecstasy for the search for oneness with God. My approach to the photography in Istanbul (seeking oneness with a place) attempted to pay homage to them in a place where their philosophies have a historic basis.

Sounds fascinating. I imagine Istanbul is a place that exudes history, philosophy and culture from every pore. I'm curious to know what you mean by "the Citadel"? Is it an affectionate name for Istanbul? If you can answer this question, you'll not only have the perfect title for your book, you'll also have the introduction!
Finally, are you also going to deal with the non-Islamic aspects of Istanbul?

In Khamra, I spent 24 hours straight exploring the city. You see a spectrum of the secular and religious, as well as a range of different cultural areas of the city (upper middle & lower class, Roma, tourist, historic, etc). I ventured through it a path that doesn't linger too much on any one area, but shows enough that I hope it shows the interconnectedness of one to the others. It is a really incredible city, as impressive as any in the world.

Citadel is a separate work -- my second book, though composed of earlier photography. The title comes from something a boy said to me in Romania. The Citadel is the old area of the city, the dense urban part. I told him I was from New York, and he said, "The citadel is everywhere." I thought it was beautiful and poetic, and I incorporated it into a story I wrote as a companion to the photographs in the book.

That's a memorable little anecdote. Out of the mouth of babes!