As someone pointed out, just think, and if someone asks, respond, "that this is my hobby".
Most people understand hobbies and they understand that lots of people may have hobbies that are a bit obscure, and they sort of seem to let things go. I mean some people built things, miniature ships, bird houses, some people collect stuff, some people hunt antiques, some people drink, some people climb sheer cliffs, etc etc.
There is no logic necessarily associated with hobbies, it's just what people enjoy. And most people understand that.
So if you like taking pictures whether analog of digital, small or large format, and you get the big quiz, you only need to respond that, "Hey dude, it's my hobby."
And when wandering around with your camera, no need to feel self conscious, ....you're just doing your thing...... your hobby.