Looking to purchase dslr for minus temperatures

Started Aug 15, 2013 | Discussions thread
bobn2 Forum Pro • Posts: 60,454
Re: Looking to purchase dslr for minus temperatures

MarshallG wrote:

Rod McD wrote:

I'd also recommend the Pentax K5 and it's more recent incarnations, the K5II or K5IIs (which lacks an AA filter). They're a very well featured, well built, reliable, water, dust and cold resistant, small DSLR. They're rated to -10C. Pentax's lens range is well suited to the outdoor photographer (in the sense that you can buy some excellent small light primes). The range caters for most needs, but they don't offer TS lenses or have the range of options that C&N do in very long lenses.

Suggest you read the DPR review.

Cheers, Rod

The ratings don't really mean anything in terms of actual performance, just how much liability that their lawyers are prepared to accept. In the past, the commercial temperature range for electronic components was quoted a 0-70C, which means that the manufacturers wouldn't have a claim against the component suppliers if the component failed being used outside that range, so, 0-70C has become the default warranty range for most electronic equipment (usually cut at the top end to allow for imperfect cooling, etc). More recently, with the change from bipolar to CMOS technologies, the range has got higher, -40-85C being typical - nonetheless it only takes one component to have a 0 limit to limit the whole thing. What is more likely to cause a low temperature limit is freezing of lubricants, and you have no information in which lubricants have been used or what is their limit.

That is not my industry experience.

Commercial, Industrial and Automotive grades require different certifications and tests. A Tier 1 vendor like Pentax most likely ensured that each component (including the lubricants) was certified for the temperature rating, and the entire system is typically tested across the temperature rating. These certifications are usually very expensive to perform, because you have to test across all conditions, which is all known sample variants, temperature and voltage variants, and you need to test a statistically significant number of samples.

Of course it's a warranty issue, but warranties are expensive. If a manufacturer claims a wider temp range, it most likely mean they tested to that range.

What happens if a product is rated to -10 and you take it to -15? Probably nothing, but there is a probability of failure, which will increase with longer exposure to the low temperature and use at the lower temp.

From your reply, I can't work out what you are saying is not your industry experience.

That the standard commercial rating was 0-70 but has increased to -40 to 85? I can give you any amount of documentary evidence to support that.

That the most likely cause of failure if the rating falls short of -40 is due to lubricant freezing? What else would it be?

Anyway, so far as supplier qualification goes, these are mass produced product, suppliers will be qualified, but after then generally the suppliers specifications are accepted except for key components. As you say, certifications are very expensive, which is why they are only done in particular safety critical markets (automotive, aerospace, medical). Frequently it happens when a new supplier is being qualified, their components will be thoroughly tested to see if they make the grade. Temperature range is in any case a statistical matter. It is highly unlikely that every single copy of a component rated down to -40 will fail at -41, the real question is what is the residual failure rate at the temperature. For this reason these thing are often certified by design rather than testing - the testing would just be far too expensive.

-- hide signature --


Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow