Here’s the problem, that Mode Dial on the Canon 7D and 5D, it rotates far too easily. In fact, it commonly rotates with the slightest encouragement – a gentle bump. Something that easily happens when flipping the On/Off switch. More than a few folks have complained to me about it. The issue came to a head for me a few hundred feet over the Gulf. I was flying along, firing off images of the convoluted stream patterns in the marshes, when I did a quick check on the LCD monitor – crap! everything blown out!! The dial had rotated to “M” from “Av”. Errrrrrgh!!
A few years ago I was working in north central Kenya and my 4wd had mechanical issues beyond my resources to fix. I pulled into a frontier town-looking auto shop, popped open the ‘bonnet’ and look at that problematic alternator. Immediately I was surrounded by professional mechanics – seemed Isiolo was a town where every male was a mechanic. After considerable shouting and threats by me to keep your hands out of my motor this elephant-sized human strolls up wiping his hands on a rag, the crowd parts like the Red Sea. He stares into my motor, I say “alternator I think”. He looks a bit longer then takes the wrench from me and tries to free the bolt – the cheap wrench snaps. Without hesitation he reaches in with his hand and forearm and breaks the alternator free, saying, “It just needed bush technique.” An hour later I was off and running.
Some solutions are simple – bush technique. In the case of a Mode Dial – gaffer tape.
I wish Canon had taken care of this in the design lab. It’s really simple Canon designers, just create a click-stop or small flip-lock. This solution is an old one, found on numerous cameras over the past few decades, call it design bush technique.