As I visit New York City often, I frequently see amazing photo opportunities in people. As I have just recently started out in photography (I took my first class at school last year), I have occupied my time by taking pictures of signs, trees, animals, buildings, etc. But lately, I have become more interested in photographing people. My question is: how do you ask someone if you can take their picture? I know it can be as simple as "can I take your picture?", but don't people change the way they're acting when you ask that? How can you preserve the moment without being rude to your subject? Thanks!