It's that flash at the top that does it. Throws everything off-balance. OTOH at least it's not the 70-300 .
I bought the hand strap when I got my 1Ds2 three years ago and frankly couldn't get used to it. I never actually used it. You can have it if you want it, though the shipping might be too much even if the strap is free ...
BTW, thanks again for the 17-35 EOS mount. Here's one from Monument Valley a couple of weeks ago, 19mm:
Lovely late afternoon ...My secret doesn't help you - I use a tripod 85% of the time, though that means I then have to lug the tripod too. I'm just glad I never use flash.
Cheers!