I don’t believe in owning just one camera bag.
I admit, I have a thing for them, but that’s not why I own quite a few. It’s because I truly believe that there’s no such a thing as an “every ocasion” camera bag.
See, some bags are small. Supposed to hold a mirrorless and an extra lens, usually. Some are quite big. You could carry a large camera and even extra clothes if you happen to spend a night away. Some have a rain cover, but the majority doesn’t. Some are made of beautiful canvas, and some are made of nylon or leather. It’s easy to see that there are advantages and disadvantages in all of them depending on what you need.
Light or heavy load? For each situation there’s a need, I guess. It’s as owning more than one trekking backpack: you don’t want to carry a 70-liter backpack in a single day trek. Then again, you couldn’t fit a tent and a sleeping bag in a 28-liter one.
I’m a shoulder bag guy, by the way.
Whenever I feel like strolling with my Leica M3, I pick my favorite bag, a small National Geographic Earth Explorer NG 2300 shoulder bag. It has a little removable insert that can hold two extra lenses or a small camera and an extra lens. It’s great for a book or notepad if I decide to stop for a cup of tea somewhere.
If the weather isn’t looking so nice, I like to take out my Lowepro Streamline 250. It’s a bit like my favorite National Geographic, but it seems to handle a light rain better since it’s not canvas. I’ve also used it on short treks, but I don’t know if I’d recommend a shoulder bag for that for anyone else.
If a heavy rain is coming, I have another Lowepro, a Pro Messenger 160 AW. It’s heavier and larger, but it has a rain cover. I rarely use it, but it’s probably my toughest bag.
Whenever I think of spending the night out, there’s my biggest bag, another National Geographic model, the Explorer NG 2478. It’s huge but comfortable to carry, and has two removable independent inserts. I can carry two or even three cameras in it, some clothes, a book and a notebook or tablet. It’s also pretty useful when I have to carry loads of equipment to a class or studio.
I couldn’t part with any of them, really. Maybe if I only had one camera I would end up having only one camera bag, but, as a photographer and camera collector, I keep using them all.