To you to adjust the lengths of up and down straps and not be sufficiently maintained hand but allowing anyway to manipulate the controls. The only possible thing and settle the iso (on 600D).
But he completed his great role, namely, to have a support behind the obvious hand of being always has grabbed his camera. finished cramps and sweaty palms.
more you hang the gun strap "shoulder" on the left and secure the device you wear on the hip!