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09-14-2018, 10:23 AM   #1
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Milky way

I was in the middle of nowhere near Brandon, Manitoba, It seems there are lights visible almost anywhere! Any way, this is my best shot.

My concern is all the noise along the bottom edge, I ran it through Define 2 but it's still noticeable, is this acceptable? If not how can I reduce it? 38 seconds, F8, ISO 1600, 14mm with Pentax10-17 Fisheye.

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09-14-2018, 10:31 AM   #2
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QuoteOriginally posted by tuggie76 Quote
If not how can I reduce it? 38 seconds, F8, ISO 1600, 14mm with Pentax10-17 Fisheye.
The kind of exposure that I use if 180 seconds at f/2.8, ISO 800. Aperture f/8 doesn't let enough light coming to the sensor, 38 sec. is also too short unless the intention is to align and stack multiple exposures.
09-14-2018, 10:41 AM   #3
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do you have astrotracer?

if not, another way to go here is to shoot several identical shots then align them and use a median blend technique to remove the noise. It works well but requires much more hands on that a single shot.

It may help to use a longer focal length and vertical framing which will increase the illumination from the stars and make the milky way generally larger in the frame
09-14-2018, 11:03 AM - 1 Like   #4
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QuoteOriginally posted by mikeSF Quote
do you have astrotracer?
It looks like they do as the EXIF says it was taken with a K-3ii. I second this suggestion. Depending on which direction you have the camera pointed you might be able to get to a 2 minute exposure with that lens without issues. Pointing it north would likely show more trailing in the corners since astro tracer doesn't do rotation only x/y movement but when you are that wide it still shouldn't be too much of a problem.

Shooting at f/8 is basically a no no for astro photography and typically I will only stop the lens down .5 to 1 stop unless it is one of my really old ones that needs more to overcome the fringing problems it has. Then with those I stack the images to drive down the noise.

For something like this I would say the best approach would be to do it as several shots. Do 4 to 8 with astrotracer at ISO 400, 60-90s each (120 if you don't get bad trailing in the corners), at f/4 to f/5.6. Then stack them (use something like DeepSkyStacker as it does a good job with stars) and bring out the detail in the sky and ignore the blury foreground. Then I would do a few non-astrotracer shot for the foreground until I got the right exposure. Then I would combine the starfield with the foreground for the actual final image.

Man I would kill for a night sky like that. At 60 seconds at f/2.8 ISO400 (I think those are the settings I used) with the plastic fantastic 35mm f/2.4 in the dark place near me I have to do a lot of post processing to bring out any detail in the milky way. When I look up at the sky there it appears as a strip of slightly higher star density.

09-14-2018, 11:27 AM - 1 Like   #5
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Why did you use f/8? Shooting wide open (or stopped down a little if the lens isn't sharp at max. aperture) will gather more light and give less noise.

I assume you used used raw (DNG or PEF) format for your photo, and processed later. Noise became more visible as you brightened the image. The ground had no illumination except starlight; it's all noise, no signal. You can reprocess using a brush or other tools to only brighten the sky. The ground is so dark just leave it black.

If you reshoot, you can try one very long exposure for the ground to get more signal, assuming there's something interesting on the ground worth showing. That requires using layers to combine separate frames for the sky and the ground. Use the astrotracer for one sky shot, no astrotracer for one ground shot, possibly with different shutter/aperture/ISO for the 2 photos.

If you want something easier, just retake the image wide open, with all the settings as per your original photo, to see the difference. A new photo at f/4 will collect 4 times as much light as your original f/8.
09-14-2018, 04:41 PM   #6
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Great advice guys, thanks. Yes, I used astrotracker and have other images up to 4 mins with no star trails. I think I tried f8 with a shorter time to see what effect it had, you have pointed out the error of my ways! I won't be back there before the end of October, if it's not too cold I'll have another go. It was dark there, and there are bears around, so a little scary on your own!
09-14-2018, 05:12 PM   #7
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Here is an astrotracer shot I did earlier this week of the Milky Way in the "dark" area near me. This was basically pointed striaght up taken with the SMC 35mm f/2.4 DA (plastic fantastic).

Camera: K-3 with Astrotracer
Lens: Pentax SMC 35mm f/2.4 DA (plastic fantastic)
ISO 400
60s
f/3.5
09-14-2018, 05:42 PM   #8
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Here's another shot, 43secs, F8, iso 1600. I copied the raw file, did my adjustments, then blended the copy into the bottom of the frame before adding a foreground of the same area taken before dark.
The foreground seems a bit darker here than on my monitor.

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09-15-2018, 09:15 PM   #9
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An example of the Astrotracer with Pentax K-3ii and the 10-17mm FE

Pentax K-3ii + SMC Pentax-DA 10-17mm F3.5-4.5 Fish-Eye ED [IF] @ 10mm
113s [Bulb / Astrotracer], ƒ/4.5, ISO 1600



La voie lactée sur la rivière Ausable / The Milky Way over Ausable River
09-16-2018, 06:51 AM - 1 Like   #10
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QuoteOriginally posted by Weevil Quote
An example of the Astrotracer with Pentax K-3ii and the 10-17mm FE

Pentax K-3ii + SMC Pentax-DA 10-17mm F3.5-4.5 Fish-Eye ED [IF] @ 10mm
113s [Bulb / Astrotracer], ƒ/4.5, ISO 1600



La voie lactée sur la rivière Ausable / The Milky Way over Ausable River
Ii take you are in the southern hemisphere as it slopes the other way.
09-16-2018, 10:56 AM - 1 Like   #11
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Nope! I was just south of the Canada border (NY State in USA), but heading to the west... Shot taken between Midnight and 2 AM...

Last edited by Weevil; 09-17-2018 at 05:10 AM.
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