In reply to SidharthaDongre:
> I use a Think Tank Digital Holster 20 v2.0, alongside the Think Tank chest harness. I currently carry a Canon 500D with a Sigma 18-250mm mounted. As it's inherently extendable, when I had an 18-55mm I was able to fit a 70-300mm and cleaning equipment in there also. Tis pretty much bombproof, you can see pics and a brief write-up if you scroll down at the following link:
Interesting, especially now that I see they make a case big enough for my 1D with a lens on.