Canon 5DMkII Failure Rate

Discussion in 'Reality Check' started by novascotiaskier, Feb 7, 2009.

  1. novascotiaskier

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    From Michael Reichmann's Antarctic trip: 6/26 new Canon 5D Mk II's failed. I don't have a stats book handy, but the upper end of that failure range is probably, what, 35% (95%CI)? 40%?

    That's not a great showing and I guess we'll have to wait and see if it is due to design issues or early manufacturing defects.:(
     
  2. shaun

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    Very impressive! :hsugh: Perhaps they pushed that one out of the factory a little too soon.
     
  3. brokenhat

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    I have 3 friends with the 5DMKII and no issues at all, so that lowers the failure percentage quite a bit. :cool:
     
  4. novascotiaskier

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    Not really. Going from 26 to 29 total sample size, and I'm assuming here that your 3 friends all shot outside for 2 weeks in light rain and temperatures hovering around zero, will for sure drop the top end a bit, but not a lot. Not down to something like 2% which is where I would have expected to see it. What is needed is a much larger sample size. Something in the 100's.


    For those not up on the math, here is a a very short backgrounder:

    You often hear during an election of '49%' of voters choosing party 'x' and the poll being accurate within 3%, 19 times out of 20. This is a sample confidence interval applied back to the population as a whole and is what I am estimating here to the non-random sample of Canon 5d Mkii's. (I'm ignoring the non-randomness, because I doubt it has any affect in this case)

    The way the statistics work, applying the roughly 25% failure rate of the sample of 26 back to the overall Canon 5d MkII population requires a bunch of math (which I haven't done, hence the reference to not having a stats book handy) the end result a confidence interval with a low end I'd guess as 10% and a high end I would guess as 40%. So if you then checked every single 5dMkII out there, you would be 95% certain that the actual failure rate of all of them would be in this range.

    By adding three more to the sample (again, assuming they shot for two weeks outside in temperatures around 0 in light rain as the other 26 did) for a total of 6/29 failures, will drop the upper end, as Matt says. What is really needed is a MUCH larger sample to narrow the range down.

    My guesses above are based upon my experience running quality assurance programs on high volume (10,000 units a day) production of communications equipment. I guarantee you my guesses are wrong.

    But rather than get lost in all of the math, debate about randomness, self-selected samples, and data normality, I will summarize my point by saying that what struck me is that the failure rate is so high for such a small sample. This means that the real failure rate is likely very high and this is what worries me. Unless the camera is designed and manufactured only for studio work, this is not something that should be happening with a piece of highly engineered gear made on a relatively low volume production line.
     
  5. Worsl

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    30 is usually a very sufficient sample size for confidence intervals actually. Very accurate and reliable. The more the merrier but 30 usually does the trick. Doesn't make sense to me but it was proven in my stats course last semester.
     
  6. Arod

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    I have yet to hear any failures in normal conditions that I will be shooting in with mine once I order.

    I suppose as long as I don't travel to Antarctica any time soon I should be safe and sound.:kekeke:
     
  7. Crandall

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    I'll cancel the plane tickets then :happysad:
     
  8. RoryTate

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    I believe Antarctic use would constitute as an outlier in your sample.

    If I were shooting for money in extreme conditions, I'd like to believe I would have chosen a weather sealed unit.
     
  9. novascotiaskier

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    Remember it is summer there, but I can only go by what Michael stated in his article, which was conditions were banding around zero degrees and there were days of some light rain.

    Hardly extreme. Pretty much what we have here today, in fact. I have shot in far worse conditions with less robust gear (i.e., my D70s).
     
  10. novascotiaskier

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    Yep. You should be fine as long as you don't venture outside when the temperature drops to near 5 C or below, or if there is a light rain or mist.:lol:
     
  11. Gordon S.

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    Canon seems to be having a lot of first-run issues with cameras these days. It seems every evolution they have has issues for the first 6 months and then they resolve everything. To their credit they usually seem to resolve the issues, but they definitely need to step up a bit on the QA for launches.
     
  12. Glen C

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    You'd think given the amount of money people dish out for it Canon would've given it some weather sealing.
     
  13. Arod

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    lol

    Here is the thing though. I frequent the largest wedding photography board in well...the world and folks on there are out shooting every day in Every part of this continent and there is not a failure rate anywhere near (if any) this Antarctic trip from what I have read.
     

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