I will recommend ThinkTank backpack, Streetwalker, the smallest in the series.
I can't post link yet, cause I'm a new user here, but just google ThinkTank Streetwalker and see the specs and photos at the official site.
Able to fulfil your equipment needs, has All Weather cover, tripod mount attachment, and probably some space leftover after you packed your equipment in.
Most important, I feel it's quite comfortable and has the airflow cushion thingy at the back, and it's light at 2–2.8 lbs (0.9–1.3 kg).
Especially when you are going on trekking, every 100g matters and comfort matters. I learned it the hard way :P
Personally I own 2 ThinkTank backpacks (Streetwalker Pro & Airport Antidote v2), 1 Billingham shoulder bag, and a few Lowepro (which I have sold).
I find ThinkTank bags are comfortable, and are able to load more than the it seem (compared to Lowepro).