Taking candid shots of strangers in public involves a certain amount of surreptitious maneuvering, of seeming to be doing something other than what you're actually doing. Apparently admiring the cathedral's flying buttress while composing a shot of the family of five at your elbow and waiting for them to compose themselves is the sort of patient and yet contorted thing you find yourself doing.
The Nikon D80 I use isn't noted for being spy, which means I get busted, grimaced at plenty, and shouted at occasionally.
So I envy this fellow photographer her considered, in-the-background style and black Samsung (possibly this one) which is at the "silent running" end of compacts. Neither of us broke cover in spite of taking a minute or so for several shots each.
UPDATE: This shot was taken during a visit to the l'Orangerie.
More spy shots of strangers.