nmguy Offline Upload & Sell: Off
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p.1 #16 · p.1 #16 · Do the ShutterLife 'predictions' make sense to you? | |
I've found there are about as many ways to calculate MTBF (shutter life) as there are ways to make soup. They can range from purely mathematical solutions that use unverified source data or they can use test methods that range from easy to tortuous. Then the question of statistical methods to evaluate the test data can vary from favorable to hideous. Also in the statistics realm, what is the criteria for a 'pass' condition? Is it 50% survival, sigma (approx 68%), 3 sigma (approx 90%), 6 sigma (approx. 99.999%, no one uses 6 sigma on deliverable product, it's just an MBA thing). No one describes their methods.
After all of that commotion, MTBF really only examines the design, not manufacture. For example, if tests are used on a pre-production model to gather MTBF data, an experienced lab tech (someone with knowledge and experience beyond what a production worker has) probably put the test unit together under relatively unhurried conditions. That doesn't speak for the production worker who has to put 25+ of these things together every day. What about bad supplier parts or a new production worker that didn't get the secret handshake on the dimension that was a bit off on the manufacture instructions?
I'm not aware of any camera company that explains how they determine MTBF either. I'll bet every manufacturer has a different method. So with that, comparing between manufacturers is most likely a fool's errand. Comparing MTBF within a company is about as far as I'd have any confidence.
As a hobbyist I'm pretty much guaranteed I won't need a shutter replacement (barring a tired production worker, or in my case a D600). Something shiny and new will distract me before shutter failure happens. Grace to pros who put a lot more shutter openings on their camera.
BTW, I have several soup recipes, they may not be to your taste though.
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