[Leica] IMG: Testing SL For Milky Way Imaging

Thu Jun 22 13:15:05 PDT 2017

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"*
> >>>
> >>> _______________________________________________
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> >>
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