Archived posting to the Leica Users Group, 2015/03/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Maybe you know the answer why when I didn't stop down the moon was not very sharp at all. I think I was shooting at f8 too. Both times. So an expensive very fast tele would have not done it. You'd still be needing to stop down. But if one was shooting with an ideal for moon shooting 100omm lens you'd not be stopping down more than a stop or two. On 3/17/15 7:28 PM, "Mark Rabiner" <mark at rabinergroup.com> wrote: > Thanks for the info Howard sorry if I was hard on you. > I shot it too that night and a few years later and it was not f16 rule for > sure but very dark red. I was at iso 6400 and my shutter speeds less than > recommended. As no film I don't think was iso 6400 I could say I got the > shot but could not have in the days of film. At least that's how I felt at > the time. > > > On 3/17/15 4:39 PM, "Howard Ritter" <hlritter at bex.net> wrote: > >> Mark? >> >> Actually, blur due to the Earth?s rotation is not really evident in this >> image. In 2 seconds, an object on or near the celestial equator (like the >> Moon) will move through 30 seconds of arc, which is 1/60 of the Moon?s >> angular >> diameter. In the small image, this is a fraction of a millimeter. I >> cannot >> detect this in my image even when viewed large. The image of the Moon is >> rather poor, since it was taken with a relatively short FL (for an >> astronomical object) of 400 mm, and focus was questionable, since modern >> lenses seem not to need infinity stops any longer (except when they do). >> If >> you look at the stars in the field, you?ll see that there is no ?trailing? >> due >> to the Earth?s rotation, which would affect them the same as the Moon. The >> stars do not quite appear as points, probably again due to imperfect >> focus, >> but they are round, indicating that the exposure was short enough that the >> tiny amount of trailing was small compared to image imperfections. And in >> any >> case, I was not going for a high-definition image of the Moon?s face, but >> of >> the eclipsed Moon in a starry sky. You?re certainly correct that a good >> image >> of the Moon itself, filling the frame or even bigger, would have to be >> made >> with a shorter exposure. Such images are usually made with telescopes on >> motor-driven mounts that track celestial objects. But since the Moon is a >> landscape in full sunlight when it?s not eclipsed, the f/16 @ 1/ISO rule >> of >> thumb works. A camera @ ISO 400 on an f/8 telescope would need a shutter >> speed >> of about 1/800 sec for the un-eclipsed Moon, and the blur due to the >> Earth?s >> rotation without the motor mount would be then about 1/50 of a second of >> arc, >> equivalent to about 100 feet of distance on the surface of the Moon and >> therefore totally invisible when viewed at any scale. >> >> I needed 2 sec @ f/8 and ISO 6400 because the darkest part of the fully >> eclipsed Moon is dramatically darker than the un-eclipsed Moon, on the >> order >> of 1/10,000th as bright, a fact that is not obvious to the visual >> observer. >> >> As for the orbital motion of the Moon, it?s in the opposite direction to >> the >> Moon?s apparent motion in the sky due to the Earth?s rotation, but it's >> negligible in any case. >> >> ?howard >> >> >>> On Mar 17, 2015, at 10:36 AM, Mark Rabiner <mark at rabinergroup.com> >>> wrote: >>> >>> 2 seconds an amazingly long exposure for the fast moving moon. >>> The blur is plainly evident in the image even quite small. >>> >>> http://forums.popphoto.com/showthread.php?338537-Moon-minimum-shutter-speed >>> >>> >>> On 3/16/15 5:13 AM, "Peter Dzwig" <pdzwig at summaventures.com> wrote: >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information > > > -- Mark William Rabiner Photographer http://gallery.leica-users.org/v/lugalrabs/