Archived posting to the Leica Users Group, 2017/06/22
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hi Bob, I am using a 15mm lens and 30 sec. is good for no star trails. I use 500 as the numerator. I use Sky Guide to see where it will be, but there are others. I was out last weekend shooting the Milky Way and got some nice shots and did a pano of six frames. I think this was at 25 sec. Leica Users' Gallery <http://gallery.leica-users.org/main.php?g2_highlightId=51631> ? Gene Duprey <http://gallery.leica-users.org/v/GRDuprey/?g2_highlightId=442261> ? 20170616-_DSC0182-Pano Gene On Thu, Jun 22, 2017 at 1:43 PM, Bob Adler <rgacpa at gmail.com> wrote: > Hi Gene, > Thank you. > How do you prevent star trails with that long of an exposure? The normal > rule to prevent trails and keep the stars sharp is 500/lens focal length ( > I use 300 to 350 as the numerator). So using the SL 24-90 @ 24, I get a > maximum exposure time of 15. I used mostly 20sec on most of these, though > one was 15sec. > Are you using a star tracker of some sort? > > Bob Adler > www.robertadlerphotography.com > > > On Jun 22, 2017, at 10:53 AM, geneduprey2015 at gmail.com wrote: > > > > I'm surprised you used such a high ISO. I have been using 3200 or 2400 > with great results and between 25 & 30 seconds. Great shot though. > > Gene > > > > Sent from my iPhone > > > >> On Jun 22, 2017, at 10:49 AM, Howard L Ritter Jr <hlritter at twc.com> > wrote: > >> > >> That?s a very nice capture of the region towards the center of the > Galaxy, Bob. And even expanding the image on my screen, I don?t see any > bothersome noise. There?s virtually none in the dark regions of the hills, > and the mottling in the lake and the sky I think is primarily due to the > innumerable stars. In any case, the SL?s performance at ISO 12500 is > impressive. That region is my favorite binocular target, and now that I?ve > discovered how to nearly eliminate the effects of light pollution in my > suburban sky, and begun to do sky imaging, it will be a target for that as > well. > >> > >> I don?t recall whether you mentioned seeing them when I first posted > them, but I took some similar shots of the Southern Hemisphere Milky Way > from Australia in April. I took them with a Nikon D810A (the > astrophotography model with the less IR-restrictive sensor cover plate) and > the Nikon 14-24mm zoom at 14mm or the 24-85mm zoom at 50 or 85mm. The shots > with the zoom were done with the camera on a tracking device to avoid star > trailing. I used ISOs of 1600-6400. > >> > >> http://gallery.leica-users.org/v/hlritter/Gallery_001/ < > http://gallery.leica-users.org/v/hlritter/Gallery_001/> > >> > >> I stretched the histogram of my images in PS by moving the white-point > slider to brighten the stars and the black-point slider to darken the > background sky, then fiddled with both, plus the grey-point slider, to get > the effect I wanted. To get rid of vignetting, I also applied a flat-field > correction frame that I took in daylight with a couple of layers of white > T-shirt over the lens, and the camera aimed away from the sun at a sunlit > scene, and then converted to greyscale. I think my images as posted are a > bit hyper-real, but that?s a goal of photographing any celestial targets > other than the bright moon and planets. In any case, they carry the flavor > of the visual impact of seeing the Southern Milky Way and the Magellanic > Clouds, for the first time, from the deep darkness of rural Australia. The > left side of the region of the MW that I imaged adjoins on the right your > region of the MW at the dense star cloud in the center of your first image. > The very different orientation of the MW is what happens when your > viewpoint is rotated 65 degrees clockwise! > >> > >> Did you do any post-processing of these images? They have the look of > raw images to me. If so, I?d be interested to see what the result of a > histogram stretch might be. Would you mind sharing the raw file with me so > I can play a little? I?ve added a couple of the raw images to my album so > you can see the difference post-processing makes. > >> > >> It?s possible to see very short star trails by enlarging your images. > The rule of thumb is that they won?t be easily noticeable if the exposure > time is not more than 300 sec divided by the FL in mm, so your 20-sec > exposures at 24mm are pushing it. If you?re going to do much of this sort > of thing, a camera tracker can be had for about the price of 2 or 3 SL > batteries? ? Some of my images were exposed for longer than the rule of > 300, which is possible when the region being imaged is well away from the > celestial equator, where the stars move fastest. > >> > >> (Pardon me if I?m telling you things you already know!) > >> > >> ?howard > >> > >> > >>> On Jun 21, 2017, at 5:28 PM, Robert Adler <rgacpa at gmail.com> wrote: > >>> > >>> Last night I went up to Silver Lake in the Sierras. It's at about > 7,800' > >>> elevation. I went to see how the SL with the SL24-90mm would work with > >>> Milky Way photography. The two images were taken at 12,500 ISO @ 24mm, > >>> f/2.8 with a 20second exposure. I shot from 10:30pm until 3:00am... > >>> > >>> Though there is a lot of noise, I don't find it distracting. The drama > of > >>> the center of our galaxy seems to outweigh any noise issues. Please > click > >>> on the image to make it larger to fit your screen: > >>> > >>> http://www.robertadlerphotography.com/p133735760/h8e052599#h8e052599 > >>> > >>> I would appreciate others' opinions as to whether or not they find the > >>> noise distasteful or does it look more like film grain. The images were > >>> post processed in Capture 1. > >>> > >>> Thanks for any opinions in advance, > >>> Bob > >>> > >>> > >>> Bob Adler > >>> www.robertadlerphotography.com > >>> *"Capturing Light One Frame At A Time"* > >>> > >>> _______________________________________________ > >>> 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 > > > > _______________________________________________ > > 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 >