I'm using a Lowepro Micro Trekker 200, an awesome backpack. Why? Cuz it is really comfortable, padded and has lots of room for lenses. It can hold my Nikon D80 attached w/300 mm lens. I love all the small pockets with clips, zippers, etc. On the outside pockets for cell phone, or other little things. There is a strap for tripod but mine is pretty heavy and I don't attach it to the backpack. Have the best hubby, he carries my tripod
Last week I climbed uphill, over rocks, holding on to roots to take shots of the waterfalls. Got my hands free, me and my camera safe for this adventure. Then I knew, this was the right backpack for me (did not like the Slingshot). Bought it for 90 (Canadian) dollars.