sing it brother!
i cant tell you the number of times i have bumped, just a bump, the front filter housing and about started crying because i KNEW it was going to screw up my lens's ability to focus.
hell i have had manually focusing the lens make 1 particular one i had go allll sorts of crazy. i was so mad i almost bought the sigma 50 1.4 ... then i recalled the nightmares of the sigma focusing issues. ie; wont focus out of the box, kiss brand new lens goodbye for two weeks to have sigma fix their retarded factory calibration system.
i think i have had to send canon lenses in 3 times for a cranial bumb, and maybe twice where it turned out to not have any issues.
you wont see me say this often but that little Nifty Fifty wont do that to you... but the 50 1.4,,, jeezus such a sensitive little ****.
my wife wants to use my 50 1.4 on her T2i, the same lens that was sent in for calibration a few months ago when it was only about 5 months old after some bump some where, and i ask her to be so careful cuz its so sensative to impact.
i dont even put my lenses front element down when i take them off the camera because the sheer weight of the lens pushing downward on the front ring and causing any movement.
people think i am over exaggerating.. nope i would never do that, i love my 50's, but they are big cry baby's and bruise so so easily.