recommend me a camera friendly backpack/hydration pack

I've recently bought an SLR and wanted to take it out with me on the bike. It's a bit of a lump so difficult to transport.

Any suggestions for a decent backpack that accomodates camera and up to 3 litres of water + essentials?

I find when I take my SLR in my back pack I can never be bothered to keep stopping, taking pack off, dig it out etc…..
I've got a Vaude Splash Air 20+5 and it will fit in there fine.

I was looking for a more accessible solution and ended up buying a Think Tank Digital Holster 10 & the accompanying chest harness. It's really well built and holds the camera firmly in place. The straps are very adjustable so you can get it just where you want it.
It is big enough for a D80 with 18-135 & the end of it extends to accept the 70-300 VR lens.
The D80 is a bit of a snug fit, so it might be worth considering getting the next size up if you don't have a 'small' SLR.

I used to use a Camelbak HAWG but recently changed to a Wingnut Adventure. Once you've got the wingnut on the weight isn't felt on your back, truly the best pack I've ever ridden with.

I use a HAWG with a D80 and attached lens, spare lens, flash, mini-tripod as well as jacket, tools, and normal riding stuff. It's heavy when full but really stable and comfy when riding.

I just use my camelbak (think it is a 3l blowfish) with my camera in a case inside. My camelbak is the one that expands via a zip if required, but I seldom use that expansion, even with the slr in. It is a pain to stop and get the camera out, but I only carry it every now and again.

HAWG with a 30D plus jacket plus riding kit plus 3L of water. Can't fault it.