Equipment 2nd-hand SLR's - How many shutter actuations is too many?

doesn't the confidence interval normally depend on your sample size? and don't pretty much all experiments standardise around classifying data that lies beyond two standard deviations of the mean as outlying?

 

I don't quite see why actuations are an accurate gauge? Sometimes if I am using the rapid shooting mode surely the wear cannot be proportional compared to single shoot?

 

That would depend on the technical differences between the two shooting modes - I would imagine that they're identical tbh.

 

No, although it does depend on the number of statistical operations performed on the same sample (see Bonferroni correction). It is the statistical power of a test that is dependent on the sample size. Of course there is also a relationship between the power and the confidence interval.

 

The wear on a shutter comes from the acceleration and deceleration of the front and rear curtains. That happens no matter what, as it is a fixed speed. A single 30 sec exposure has the same actuation as a 4000th of a second. The time the shutter stays open is what changes, or at least the timing between when the front curtain opens and the rear curtain starts to close. So if you take 50k single 30 second exposures, the wear is the same as 50k exposures at 1/4000 in continuous shooting. The wear on the REST of the camera might be different. So if you see a body with 50k in one year, you can assume that thing was bashed about vs. someone that has 50k over 6 years.

 

I would not worry about shutter count . . . from memory I think 200k is life expectancy.

But if dropped that would be the more concern, or a hard life, lots of lens changes dust on sensor/internals etc.

Biggest issue for me, is checking for noise (hot pixels) on sensor and checking af . . . in case the camera was out as sold, or if canon service has taken camera out of spec to match a given lens.