Originally posted by lithedreamer The Peak Design Sling is advertised as being able to fit a 70-200 + camera + tablet. I'm not sure if it'll fit the Pentax one, but I'll let you guys know when I find out.
It should fit, indeed, but not much more. That is a LARGE lens.
Originally posted by lithedreamer I know inserts work for some people, but I hate them. I insist on bags with side access most of the time, and besides that, the ones I've tried just seem to kill me ergonomically (let's put all of the heaviest things you're carrying in one part of your bag).
That's why you should look at bags with more than one pocket. For instance (not pushing that particular model), the bag that I use is this one:
It has a bottom compartment which fits perfectly an Ape Case Cubeze insert. Heavy stuff is at the bottom, where the waist support takes the load of your shoulders. The mesh back makes it breathable (I'll never go without that ever again), it has room for a water pouch, side pockets carry the tripod, front hook the monopod, top compartment takes the odds and ends (it's large, in fact). A Ap-Tech lens pouch attaches to the waist band if needed, for quick swapping between two lenses.
This particular configuration won't let me put the 60-250 at the bottom, so it goes in the top compartment, in its own pouch. That's not "perfect", and doesn't give you side access like you request, but it works, is more comfortable than any camera backpack I've tested, and cost me less than 100$ CAD for the total (including insert and Op-tech pouch).
If you want side access, the Manfrotto Off Roads Hiker backpack (30 liters) would be a good choice.