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Old 05-10-2023, 10:34 AM
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Ryderscope (Rodney)
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Pointing the Way

The lonely tree captured in the dam in the foreground seems to be pointing the way to the Milky Way above. After walking past this dam many times I decided to try a Milky Way nightscape to capture a nightscape scene. Whilst the location is reasonably dark (est. Bortle 3), you can see that the light dome from the city of Bathurst, 15Km to the west, does produce significant light pollution - particularly noticeable when using longer exposures. It wasn't possible to capture the Milky Way with the impact that I was hoping due to the extended light dome. Nevertheless, it does tell a story of a rural countryside located not far from a large regional city. I've resisted the temptation to over brighten the night sky as I feel that it is a closer representation of what I could see.

Data for this image were captured with a Canon 60Da and Samyang 14mm f2.8 manual lens. To plan the time for the project for when the Milky Way was setting in the right position, the PhotoPills app on the iPhone was used. The data were captured around 1am on a clear moonless night and it is amazing to see just how much ambient light there is when using long exposures. Ambient light from both the sky glow and from the nearby city.

Data acquisition comprised five x 180s non tracked images for the foreground, ISO800 f5.6. For the Milky Way exposures ten subs @ 180s, ISO800 f5.6 were captured with an equivalent number of dark frames. Milky Way exposures were tracked using a Skywatcher Star Adventurer mount.

A larger version can be found here on Astrobin.

Clear skies,
Rodney
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Last edited by Ryderscope; 15-10-2023 at 09:28 AM.
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Old 09-10-2023, 07:55 AM
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Nice moody image Rodney.

Stars are pinpoint which is not easy at 14mm.

Greg.
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Old 11-10-2023, 06:46 AM
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Originally Posted by gregbradley View Post
Nice moody image Rodney.

Stars are pinpoint which is not easy at 14mm.

Greg.
Thanks Greg.
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Old 15-10-2023, 08:57 AM
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astronobob (Bob)
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Yeah nice going Rodney, it’s amazing how we perceive the night sky light and what the cameras can actually pick up, I would have thought to set the aperture closer to f 3.5 - f 4ish to collect the photon a bit quicker but I’m not familiar with the 14mm, also effects sharpness and and coma if set too fast.
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Old 15-10-2023, 09:31 AM
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Yeah nice going Rodney, itís amazing how we perceive the night sky light and what the cameras can actually pick up, I would have thought to set the aperture closer to f 3.5 - f 4ish to collect the photon a bit quicker but Iím not familiar with the 14mm, also effects sharpness and and coma if set too fast.
Thanks Bob, agreed that it shows just how much ambient light there can be. For determining the best aperture to run this lens at, I took a number of test images starting from wide open at f2.8 and stepped down the lens gradually until I was satisfied with the star shapes around the edge of the field. I landed at f5.6 before I was happy and figured that I would rather go with longer integration times for the benefit of a better looking star field. I still find that I need to apply a small amount of BlurXterminator in Pixinsight to help tidy up the field during post processing.
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Old 15-10-2023, 10:21 PM
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Originally Posted by Ryderscope View Post
Thanks Bob, agreed that it shows just how much ambient light there can be. For determining the best aperture to run this lens at, I took a number of test images starting from wide open at f2.8 and stepped down the lens gradually until I was satisfied with the star shapes around the edge of the field. I landed at f5.6 before I was happy and figured that I would rather go with longer integration times for the benefit of a better looking star field. I still find that I need to apply a small amount of BlurXterminator in Pixinsight to help tidy up the field during post processing.
Ah yes indeed,, retaining all the 14mm captures, wide angle with a flat horizon too.
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