So the question arises - again - "why do I need filters on my lenses?" And as a picture can tell a thousand words...well...I'd show you a photo if I was thinking straight at the time but I was horrified - that my camera strap came apart - and yes - my 5DmkIII fell to the rocky trail at my feet. I did think to take some pics a few days later so I could tell the tale as a warning - just imagine if this was your lens and not a filter!!! Here it is:
Lens saved but 2 very expensive filters stacked on top of my protective UV filter bent and I could not prise the two apart because of the damage - a few hundred dollars lost...unless.. over the next week I pondered and looked and fumbled over and over - trying to get them apart...eventually I had to give in to the hammer option - gawd - on such fine quality precision equipment...I needed a drink to think about it...but they were almost useless stuck together...very very lucky I had no lens damage apart from a few scratches.
And so I set to it with some pointy nose plyers first...a fanciful idea...they didn't move whatsoever...the hammer and something thicker than a nail punch was what I needed...and so I got out my rusty old tools...a few short sharp taps to push out the dent...no broken glass...phew...but still no movement. By then I had completely given them up as lost - my mind wandered to ebay and other online store options to replace them.
As a last resort I got out the WD40 and gave it a little squirt - keeping it away from the middle of the polarising filter - just in case it oozed in between the two pieces of glass. Within moments I had the two filters apart..O.M.G!...I put them back together, took them back apart..I can still use them!!! In any case the polarising filter underneath sis the most important and more expensive and it seems to have suffered no structural damage - hopefully the thread is still ok but I don't often put another filter on the top of it anyway...so happy days.
And the lesson is YES - PUT FILTERS ON YOUR LENSES TO PROTECT THEM!!! (And more importantly - have a safety harness attached to your camera if you use a speed strap...or any strap really)
On a good note - I got some great shots anyway!