There are good & bad habits (or omissions of good habits) that can cause this sort of problem.
I have noticed my lens had become unlocked more than once (though I always caught it and no lens ever came off completely thanks to the large amount of rotation needed after releasing the lock) and I was baffled as to how it happened because I have good camera handling technique when I'm shooting. But the emphasis is on "when I'm shooting".
It turned out the fault was indeed mine. When I retrieve my camera from the bag, I had a habit of grabbing the lens barrel by my left hand - and I'd grip it as close to the camera body as possible. This put my thumb right up against that button -- and then I'd pull the camera out. Just occasionally I was pressing the button and the "lifting" action was giving the lens just enough rotation that when my thumb was no longer pressed up against the button the lens wouldn't relock.
The solution is that I'm now mindful of how I grip the camera when I pull it out of the bag.
I also use a Black Rapid strap. The camera attaches via the tripod bolt on the bottom of the body. Black Rapid puts a big black rubbery washer down there so that it hopefully wont twist. But some users claim the bolt came come loose. Upon learning this, I REGULARLY check that my bolt is snug (many times per day). I have never once found mine coming loose, but I still check it. It's a good habit that takes just a fraction of a second and saves thousands of dollars in expense.
Developing good habits doesn't really take much effort and it provides good benefits.
Besides photography, my other passion is astronomy. I love science. I love physics. I love the scientific method. I tend to think along those lines.
So when someone says "this problem is caused by that defect", I tend to look at the data. I just can't get around the problem that "that defect" was causing "this problem" then every camera that has "that defect" should have "this problem" -- or at least quite a substantial majority of them. But that's not really the case. Hardly anybody has this problem. So if I employ critical thinking ... it is not rational to believe that the design is actually "the" problem (it could still contribute to it). There must be something else going on.
On the flip side, we can look at the human element, human habits and how masses of humans tend to think.
I have a friend who used to sell phones (for a major telco carrier). I would occasionally hear stories about the latest customer experience. One day he was telling me about a customer who walked in with their flip-phone (many years ago) which was clearly in two entirely separate halves (they're not supposed to come apart). Inspection of the device CLEARLY showed it was physically stressed well beyond the breaking point (the phone was ripped apart) - whether deliberate or accidental. The customer's story "it just broke". His question "did you accidentally sit on it while it was open?" Customer: "no, it just broke". "Did it accidentally fall a great distance or get stepped on?" Customer: "No, I just opened it to use it and it fell apart."
This customer was clearly "lying through all six rows of their teeth". This story isn't all that unusual for these service reps. They get the customer-is-in-denial or the customer-is-blatently-lying experience all the time. They also get honest customers too... so it's not all bad.
But my point is, if that design defect was 100% responsible for the problem and nothing else contributes to the problem, then lenses should be falling off all the time. But the issue does seem to be quite rare. This points to other contributing factors.
I do find it "interesting" (from a human sociology perspective) that threads like this one point to a product defect almost exclusively without owning up to any other contributing factor -- such as operator error.
Do you REALLY believe there's ZERO operator error involved here? I mean... c'mon... not even a little tiny bit?
Tim Campbell
5D III, 5D IV, 60Da
