I had long hesitated between the 400 and the 600 version since it mainly went me to the transport of a Nikkor 600mm / f 4, to me the 600 but much too big (size of 400 backpack is however ...) and also to was difficult. According to the manufacturer it should not fit - but do it. The specified 44mm internal dimensions are nearly 48mm - without lens hoods that could be attached to the backpack outside, however. When the lens is 600 times in there, but no longer fits otherwise very much in the backpack - it's enough for my needs but. At the two outer sides of each for about 9x30 centimeters are then (ie sufficient for camera and one or two not overly large telephoto lenses, + small items), and a little bit of space for preferably soft objects, in addition to the thickest front office the lens can be stowed. The main problem is that you can possibly need for the 600 an appropriate tripod - this but you can not possibly still be attached to the backpack (maybe you could fix one leg on the front of the pack, but would have probably unpleasant effects on their balance).
Highly recommended the backpack is also for people photography on location - Camera, necessary lenses, three flashes and various accessories can be super store it and transport very comfortable, so that your hands still remain free for several other "stuff" - saves some unnecessary programs and protects the equipment in case it suddenly times but should start to rain. Or the shoot anyway to take place in the rain.
The backpack itself is processed TOP (the zippered main compartment is at the beginning a bit hard on, which is the time but better), very robust to equip well and very comfortable to wear, even with a full load inclusive 600 Tele. Even if you weigh yourself only 50 kilos. One should for the backpack but not be less than about 1.70 m, because then he would probably be too long. He may be considerably smaller than the 600, but still quite large - so do not scare when unpacking. Best compare before ordering times with a box of the same size.