[Leica] IMG: Testing SL For Milky Way Imaging

Thu Jun 22 14:16:46 PDT 2017

Ah. Didn't get that it was multiple shots totaling 20minutes. I haven't tried panos yet.

Bob Adler
www.robertadlerphotography.com

> On Jun 22, 2017, at 1:15 PM, Gene Duprey <geneduprey2015 at gmail.com> wrote:
> 
> 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.
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>>>> 
>>>> 
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