I use the big F64 bag for my 8x10 Korona. The Korona, when folded, is about 14" x 15" x 6.5" and fits well. I can't imagine a bigger camera fitting though. I put 3 8x10 holders in the outer pouch, though I've read that some are stuffing 4 in. In the top section I stow a 19" Artar (no lens board), light meter, dark cloth, filters, loupe, etc. I strap the extension rail to the outside of the pack. I do not use the two removable pouches that are provided with the pack for my 8x10 gear. I purchased the bag direct from the factory at a significant savings.
http://www.f64camerabags.com/backpacks.html