The second reason not to use coins for size comparison is that the same denomination can vary in size either due to change in coinage or (would you believe!) false advertising. The (seldom seen) U.S. dollar coin has been at least two different sizes in my lifetime. The dime in the photo is identical to the one Steve Vinisky showed at the miniatures breakfast and is 77 millimeters in diameter. Because the large dime is rare, few people have seen it, so most people will assume dimes in photographs are the common 18 mm version. I therefore maintain that the ruler is the best reference to use in a photograph.
Kirby Fong
Not to get off-topic here, but 77mm dime? With tiny variations, the dime’s been 17.9 to 19mm (3/4″ for those of us still preferring standard measurements) dating back to 1796 (and indeed, other than bullion type non-circulating coins, no coins other than the cent and dollar have ever changed size over the same period). I agree on your point — I can see also a problem with a coin’s metallic nature unbalancing automatic controls on some cameras…but I’m just darned curious about this giant dime!
Regards,
Drew Mc Farland