Best carry on sized camera back pack?

[Johnmcd]

I need some help here. My next trip in September demands that I bring my DSLR and 300mm (air show). That's on top of my M3, new GF670, some lens, a bunch of film and my Surface Pro laptop. My old back pack is just not big enough.

So any recommendations on a decent sized backpack that still fits domestic and international carry on rules without worrying each time I board that they might object?

Thanks - John