One thing that’s always bothered me about Sony and other camera manufacturers is the lack of specifics they give when talking about weather sealing in their cameras. It seems to me the companies have taken full advantage of being able to say “this product has weather resistance” and leaving it up to what the consumer thinks that means (usually giving the benefit of the doubt to the company they are buying from; no one wants to entertain that the product they are putting money down for is less than incredible). All the while they are not backing up this marketing claim with any sort of guarantee. Unfortunately, there is no great resolution to this as I fully understand these companies can’t just be warrantying water-logged products — too many dishonest people will ruin it for everyone else on day one.
With the new a7R III, Sony has claimed that it is more weather resistant than the previous model. Roger Cicala of LensRentals popped open one of these a7R IIIs and took it apart piece by piece, detailing what Sony has done to provide this enhanced weather resistance and comparing it to other Alpha cameras.
For now, these excellent third-party teardowns and analysis articles are the best we can do to educate ourselves on what exactly “weather resistant” means.