Archived posting to the Leica Users Group, 2011/06/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Very nicely done Thanks Philippe Le 24 juin 11 ? 06:14, Howard Ritter a ?crit : > > > On Jun 22, 2011, at 9:02 PM, Lawrence Zeitlin wrote: > >> Michiel is right. The Milky Way is a band of stars stretching >> across the >> sky, visible only under extremely dark conditions. > > Not necessarily. It's visible from the moderately deep suburbs, > especially in the summer, when it's overhead at midnight during the > summer in mid-northern latitudes. Of course, it's GLORIOUS only from > really dark-sky locations. Like intermountain Colorado, where I'm > headed with my cameras and telescopes next week to do deep-sky work > at the Rocky Mountain Star Stare (www.rmss.org). > >> On a practical note, if you are in the right location and you want >> your >> camera to image individual stars rather than a smudge of light, you >> will >> need to have your camera on an equatorial mount that compensates >> for the >> rotation of the Earth. Exposures will be long. Any foreground >> object, trees, >> houses, etc. must be unmoving. > >> Larry Z (a former astrophysics major) > > Again, not necessarily. This was pretty much true when I first > pointed a camera at the sky in 1959, but not now, especially with a > DSLR like the D700, which gives good results even at ISO 6400. Check > out the image of the Milky Way I took at Jackson Hole two years ago > with mine. The text shows how simple the process can be. If I had > used a better lens, like the new 24mm f/1.4 prime (which I've just > acquired and will be taking with me this year, and the 35 and 50 > primes stopped down to 2.8 or so should do even better), the star > images would have been much sharper toward the edges and the > exposure could have been half as long: > http://gallery.leica-users.org/v/hlritter/Wyoming_001/Wyoming/Wyoming+Milky+Way.jpg.html > > OTOH, it is true that better results can be gotten with a simple > tracker, which allows longer exposures at less than full aperture > and at lower ISOs. The premier commercial product is shown here > (again, I'm taking mine out West this year): http:// > www.astrotrac.com/, but a serviceable "barn door" tracker can be > made from two pieces of plywood, a hinge, a nut and bolt, and a 1- > rpm synchronous motor. > > I'll post some images from Colorado with one of the 1.4 primes and > the Astrotrac next month. > > ?howard (who would have been an astrophysicist had calculus come to > me as easy as biology) > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >