Archived posting to the Leica Users Group, 2007/09/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Carl - Waves of that size (swells, tall rolling long-period waves, occur primarily offshore) are not unheard of in Buzzards Bay but, having watched both boats for some time, neither of them was rising and falling in and out of view. As you can see in the picture, we had a typical Buzzards Bay 1-2 foot chop in the prevailing South Westerly breeze. What looks like a swell is perspective foreshortening caused by the use of a long telephoto lens (300 mm equivalent on a 35 mm camera) and the extreme crop making the shot an effective 2000-3000 mm photo. Here's another way to think about this. Since a height of eye of about 3.5 to 4 feet (the height from which I took the picture) puts the horizon about two miles off (just about where the left-hand boat is), a boat another two miles off (just about where the right-hand boat is) would have about 3.5 to 4 feet of its hull hidden from my viewing point. Thanks for the interesting link. As I said in an earlier response, maybe off-list, many cultures didn't buy into flat-earth thinking. One in particular, if I'm remembering what I read in the book "1421" correctly, were the Chinese, who were world-class explorers well before the Portuguese and Columbus. Regards, Dick On Sep 23, 2007, at 8:26 PM, Carl Muckenhirn wrote: > It is a myth that any sophisticated people believed the earth to be > flat, particularly sea farers. > > http://www.veritas-ucsb.org/library/russell/FlatEarth.html > > c. > > BTW, your image probably shows one boat on top of a swell and the > more distant in a trough. At 2 miles there is less than a yard > distance between the surface of the earth and the tangent line from > the observation point. The foreground boat is at a distance (so > already eating part of the yard) and the more distant boats appear > more than 4 feet below the surface (assuming a 30ish ft boat in the > distance I'd guess it has a freeboard of ~3 ft, plus an other > couple for a cabin height). > > On Sep 21, 2007, at 1:11 PM, Richard Taylor wrote: > >> ... and you can even see it on smallish bodies of water, in this >> case, Buzzards Bay on Cape Cod. The boat to the left is just on >> the horizon, the one on the right about a mile beyond. The >> horizon in this shot is about 2 miles away. Makes you wonder why >> any of the ancients thought it could possibly be flat. >> >> http://gallery.leica-users.org/v/rtaylor/PICKS/SAILING/ >> IMGP7328.jpg.html >> http://tinyurl.com/23yhhm >> >> Very tight crop K10D, 200 mm Pentax-M lens, ISO 400, approx. >> f8.0@1/2000th. This crop is probably the equivalent of a 2000 mm >> 35 mm lens. >> >> Comments welcome. >> >> Regards, >> >> Dick >> >> >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information