I use the Retrospective 5 for my Nikon D700 with a set of fixed focal length lenses (50mm f / 1.4, 20mm f / 2.8 and 105mm f / 2.8). Although the bag from the outside looks almost small, this camera fits mounted with each of the three objectives and the other two in the bag. Space for much more remains then of course not. Replacement battery, mobile phone and other small items will find course soon enough space. With a larger lens mounted, for example, the 24-70mm f / 2.8, the camera does not fit well in the pocket, because the camera then projects beyond the edge of the pocket, if they are placed with the lens facing down into it. With the objective to hand it fits yet, but then you lose the capacity for interchangeable lenses. The bag itself is quite easy and with the wide strap can be above equipment for a time convenient to carry. I appreciate the Retrospective 5 especially if you travel to the city if you're in a lot of public transport on the road. There, the small bag is much more practical than a backpack. I prefer to hike, however, photo backpacks (eg the Lowepro Primus AW II or Airport Antidote V2.0) ago.
As usual Thinktank, the Retrospective 5 is processed excellently and comes with a rain cover, but one can also take out. My only criticism is the numerous, partially nested inside compartments. While this may not make sense in the larger versions of the bag, take them in the small version mutually to square off: If you fill a neighboring compartment larger than one memory card, then there is no space. This exuberant interior is certainly partly responsible for the high price of the Retrospective 5.
In short, a practical, if somewhat expensive, camera bag in which even a large camera with a set of fixed focal length lenses fit.