I must upgrade my backpack, and due to that I live in a small town (with no good equipment stores) in Sweden, I can't try out the backpack before I buy it.
Normally when I carry the 300/2.8L IS II it is mounted on the 5D mk III without the extender. But sometimes I carry the extender mounted, so my question so, will the kit (300/2.8L IS II + Canon 2x extender + 5D mk III) fit mounted in a Lowepro Pro Trekker 300 AW (http://products.lowepro.com/product/pro-trekker-300-aw,2165,16.htm
), or do I need the bigger 400 AW (http://www.the-digital-picture.com/Reviews/Lowepro-Pro-Trekker-400-AW-Camera-Backpack-Review.aspx
)? Often I do not carry the 300/2.8 and I think that the 400 AW will be unnecessary large for normal use.
When I measure the kit (300/2.8L IS II + Canon 2x extender + 5D mk III) it is 38.5 cm long and the Pro Trekker 300 AW have a height of 37 cm, but normally that is possible to fit a little bit bigger items in the bag.