Even the cutoff for copyright is more complicated than that. Last I checked, works copyrighted by an individual were protected for 75 years beyond the death of the author, without requirement of renewal, and there was an option for the estate to renew beyond that (though I don't recall details).

However, for images of a product like a camera, copyright isn't the primary concern; trademark is, and the rules for use are very different. That's why nothing learned in this discussion is worth anything, really, in this context -- most of us have a clue (if no more than that) about copyright, because it's strongly related to any attempt to make a profit from our photography, but trademarks are a whole different animal. My last employer tried to trademark his own brand of (imported, custom packaged) product, and was denied the trademark because his name was "simply descriptive".

The appearance of a product isn't subject to copyright, generally, unless the product is one that's published, like a magazine or book (and even then, the overall "look and feel" is a trademark matter, not one of copyright; each individual cover needs to be separately copyrighted as part of the issue on which it appears, for instance, even if the logo remains the same from issue to issue; the logo itself must be trademarked to prevent others from using it on their own publication). With tangible goods like cameras, trademark is the only issue of merit -- but trademark is also more stringent, in that the holder can *lose* trademark protection, permanently, by failing to defend. So, if you make images of a Leica camera and sell them on merchandised goods, Leitz (or whoever owns them now) is *forced* to pursue you, or give up their ability to defend the Leica name (or so I, a legal layman, understand to be the way American trademarks work).

The way around this, as I said originally, is to have permission. From a company like Leitz, that's likely to require paying a license fee, which may be wildly unrelated to the value of the goods you expect to sell. If you're very lucky, you might be able to negotiate to a relatively small up-front payment and a royalty (percentage of gross on the sales); more likely, with a company that makes most of its money on the name rather than on the merits of the product (sorry, Leitz, but that's the way I see it), you'll be given a take-or-leave offer for a license at a price no small business could begin to afford, potentially followed by Leitz licensing your idea to another vendor who can afford to pay their fee (non-disclosure might not even help, since they can claim they were approached by another vendor who was able to meet their licensing requirements).

Recommendation: make your images of cameras produced by companies that no longer exist or, via multiple mergers and acquisitions, haven't sold under the pictured name in many years. Forget Leica, Rollei, Nikon, and concentrate on Wirgin, Univex, Balda, and the like.