quixdraw wrote:
The D 7500 is rated at 150,000 - that doesn't mean the shutter will fail at that point....
It's what's called "Mean Time Between Failures", as predicted by some engineer familiar with the design and materials being used in the device.
Plus it's an "average" number.... some cameras fail much lower count, some survive much longer.
Usually there's a small number of cameras that fail early.... got through quality control but are faulty right out of the box or fail within one or two months. After that the great majority will have a very long, happy life... often far more "clicks" than they were rated. I've seen reports of some cameras that were rated for 150K actually exceeding 1 million clicks!
Think of shutter clicks like mileage on a car... suggestive of the overall use of the camera, wear and tear on all it's components, not just the shutter.
And like car mileage, not all miles are the same. Supposedly it's a lot harder on cards driving around town in stop and go traffic, than it is cruising at moderate speed on the highway.
It's similar with today's digital.... A camera that's only been used for photographs might have a lot of clicks, but only a little "on time" with all it's other electronic components. For example, if one used an average shutter speed of 1/100 and took 100,000 shots, some of the camera's internal electronics used to make images would only have functioned a total 1000 seconds... or about 16 and a half minuted. Conversely, a camera primarily used for 50 second videos that has 20,000 "clicks" on the shutter, but might have accrued 1 million seconds... over 275
hours... of "on time" with some of it's components!
Still, besides just looking it over and trying to judge from the external appearance, "clicks" are all we've got to try to determine how much "use" a camera has seen.