Originally Posted by
GrumpyDiver
Let's look at the legal and ethical issues here. In most developed countries (I believe Hungary is the only exception), it is fine to take pictures of people when you are in a public place and can see them from where you are. Some countries (usually the developing countries) may take exception if you are trying to photograph police or military personnel (exceptions apply as always), Things get a bit trickier if you are on private property and in theory you can be forbidden to photograph anything by the owners.
Ethically, things are a bit tougher. If someone motions to me that they don't want their picture taken, then I won't do it. Vendors and people in areas frequented by tourists tend to be quite averse to having their picture taken, so i will work in stealth mode in these places. In other places people are fine if you ask them, so there is no clear answer.
The other issue is compositional. When people notice that you are taking their picture, they often change their expression and can "ruin" the shot. So here I tend prefer the shot just before they recognize I am holding a camera; where they are looking at me, but have not changed their expression. The problem with that technique is that it is usually only good for one shot, and if you miss it, the opportunity is gone. In many places, people will want compensation for you taking their picture; and that can happen at home and abroad.