You may be looking at how much the memory card has left, or the counts left on the battery (but I don't think the battery could take that 6K pictures).
I don't think there is any place on the camera where you can see how many shutter counts it has left. Where did you see the number "6000"? The 5D Mark 3 is rated to have 150k shutter count so I wouldn't worry about it.
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I'm an advanced amateur, am not the average point-and-shoot photographer out there, and am willing to take any critique or advice that will improve my photography.
