My main passion is hiking in the mountains. (I'm surrounded by some very nice mountains) I will carry a tripod and a camera, usually my Hasselblad 501cm and extras, in a Lowepro Nature Trekker. The pack takes up all my back and a lot of my sides. I cannot carry my 35 anywhere but the front. I've been taking a Nikon F3HP in this configuration often and have developed quite a neck for the job.
The F4 will finish me I suspect.