Why is the number of shutter cycles so low?

Question

I see that according to the Nikon's website, "the shutter of the D3S and D3X has been tested for 300,000 cycles".

At the same time, some professional photographers can make much more than one thousand shoots in one day (from several sources; alas I can't find any of those sources now), even if they don't shoot every day.

Does it mean that those people (or their company) spend six thousand dollars for a camera like D3X every two years? If yes, why there are no DSLRs with a higher number of shutter cycles?

Answer 1

No, it doesn't mean that people have to buy new cameras every few years (at least for the reason of failing camera shutters! ;-) ) Keep in mind that shutters can be completely replaced/refurbished for significantly less than the cost of an entirely new camera.

As is mentioned elsewhere, it's important also to remember that these numbers are simply statistical estimations of how long a shutter mechanism will last. It is possible that a shutter could fail at 100,000 cycles, or at 500,000 cycles. Nevertheless, when you consider the cost of a $250 repair that works out to between 0.0025 cents and 0.0005 cents per actuation depending on how many actuations you get out of your camera...

Answer 2

A thousand shots in a day is, well, an unusually large number of pictures for anybody to be taking. That averages more than one shot per minute over a sixteen-hour work day with no time for meals or restroom breaks. A thousand-shot day is what a sports photographer does at a very full day of track and field at the Olympics -- ten or twenty minutes of nothing, then full-speed motoring for a few seconds, then another "break" while you scramble like hell to get to another shooting location. And yes, if you're going to be shooting pictures for money at that kind of rate, then buying a new camera every now and then is the cost of doing business. And the chances are pretty good that the photographer will be carrying more than one camera body as well -- when you can't afford to miss the shot, you can't afford to be without a camera even after falling down the stadium steps, etc., not to mention that swapping bodies is faster (and more sensor-hygienic) than changing lenses.

Answer 3

The wording that Nikon use, 'tested for 300,000 cycles' is vague, misleading and contains too little information to make an informed judgement. It is typical marketing speak. In reliability testing we use more clearly defined terms like 'mean', 'median' or 'expected lifetime'.

Presumably they intend this to mean the expected lifetime, or mean lifetime. If that is the case you can expect roughly an equal number will fail before 300,000 cycles and roughly an equal number will fail at greater than 300,000 cycles, depending on the failure distribution.

But if roughly half will fail earlier than 300,000 cycles the crucial question becomes how much earlier? This is where Nikon supply no information whatsoever. And it is this information which is of vital interest to the average camera user.

A more useful statement from Nikon would be one like this: No more than 5% of shutter mechanisms will fail in less than 100,000 cycles and the expected or mean lifetime is 300,000 cycles.

Formal reliability testing aims to provide more meaningful information of this kind. It is certain that a company like Nikon knows a great deal about doing proper reliability testing so they will have the full information. But they (like other companies) have chosen to release incomplete and misleading information. This is deceptive behaviour bordering on the dishonest. Sadly it is the norm.

Below is a short background to the kind of information they could provide. See this link and this link.

Reliability data is normally modelled by a failure distribution pattern called the Weibull distribution. It typically describes the failure patterns of complex systems.

It has three parameters called the Shape (beta), Location (gamma) and Scale (eta) parameters. Reliability testing aims to determine the value of these parameters. Once they are known one knows a good deal about the pattern of failures that will occur during use and allows one to make statements like

'with a confidence of z% we can say that no more than x% will fail before y cycles',

which is usually what we want to know.

One can think of the location parameter as being roughly equivalent to the mean lifetime and the scale parameter as being equivalent to the standard deviation. But that is a very crude approximation that depends on the shape parameter.

I have gone on about this at some length because cameras are high value items that are critical to the professional life of many people. We have a right to expect honest and complete statements about their expected lifetime so that we can make informed choices and have reasonable expectations. Although I have mentioned Nikon in the context of this question it seems that all camera companies are equally guilty.

Answer 4

Part of the reason the number of cycles is relatively low is that the shutter is a very high performance precision mechanism. The shutter on the D3X is one of the fastest around. It has to be able to complete it's operation of moving across the frame in a three hundredth of a second and be able to synchronise the movement of the first and second curtains to within one eight thousandth of a second. And it has to move a much larger mirror back and forth in this time. And then it has to be cocked ready to repeat all this work eleven times a second!

Another reason 300,000 figure is approximate is that different patterns of use put different stresses on the mechanism. If you only shoot sports at 1/8000s at 11fps I imagine it might wear out before this figure. On the other hand, if you shoot landscapes at night at slow shutter speeds it may last longer. Temperature range and humidity will also play a part, as will manufacturing defects.

Answer 5

Shutter may fail long before this number of actuations or serve twice as long - there is no guarantee. It is just average estimated figure. Most likely it is determined by testing a bunch of shutter for a number of actuations and then studying how much wear their elements sustained. From that figure you can estimate how long shutter should last, but that is no more than estimation. The stated number is probably intentionally lowered, to reduce number of unsatisfied customers demanding refunds. Also note, that shutter is perfectly replaceable, and not too expensive, especially compared with high-end camera cost (and really only professional photographers are likely to use camera this much).