Despite always reading product manuals before using the actual product, I always seem to miss little details, or the details were omitted from the manual to begin with.
For example, I didn't know that the 1D Mark III sensor cleaning had two different modes... one is the auto sensor clean that operates when you turn the camera on or off.
Then, the camera also gives you the option to operate the sensor cleaner whenever you want. I always assumed this was the same as the above, but recently I noticed that I could hear the shutter sound like it was firing three times in this mode.
Well, I just watched Canon's "Masterclass' videos on their UK website, and learned that when you use this second, manually selected sensor cleaning, shown as CLEAN NOW in the sensor cleaning menu, the Mark III moves the shutter blades , cocking it 3 times to give a more thorough cleaning than the daily auto function.
Perhaps others may know this, but I found this very informative and will use this manual clean every now and again (even though the auto function seems to work quite amazingly well already).