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 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