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May Milky Way
Lens: Pentax FA 31mm Ltd. Camera: K3II Photo Location: Kamloops ISO: 800 Shutter Speed: Above 6s Aperture: F3.2 
Posted By: aitrus3, 06-26-2023, 01:39 PM

My first Milky Way with the Pentax 31mm ltd. lens. I used a Skyguider pro for this shot. We had hoped for more blooms and didn't anticipate the amount of light pollution that would be here. Also it was clear for 5 hours, then right when we needed to shoot the core, small puffy clouds were forming directly overhead and drifted south right in front of the band of stars. Just our luck.




I also did a test of it's performance on stars with built in astrotracer a while before this shoot. It was a quick test to look at things like coma and chromatic aberrations. At full open, for stars, the lens is fairly useless especially if using the built in astrotracer and the field rotation it suffers from. This turns the coma into some kind of awful aberration with this lens. It's best to shoot at f3.2 if you're going to use the 31mm ltd for astro. And yes, before people get on the case that 'astrotracer doesn't induce field rotation'... it does. I've documented it's affects very well. It happens with every lens I own and yet, while using the same settings and lenses, it doesn't happen at all on a proper tracking mount.



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06-26-2023, 01:55 PM   #2
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Clouds and light pollution are the banes of all astronomers. It looks like you were well positioned for shooting. Thanks for sharing your images.
06-26-2023, 02:59 PM - 1 Like   #3
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QuoteOriginally posted by aitrus3 Quote
My first Milky Way with the Pentax 31mm ltd. lens. I used a Skyguider pro for this shot. We had hoped for more blooms and didn't anticipate the amount of light pollution that would be here. Also it was clear for 5 hours, then right when we needed to shoot the core, small puffy clouds were forming directly overhead and drifted south right in front of the band of stars. Just our luck.




I also did a test of it's performance on stars with built in astrotracer a while before this shoot. It was a quick test to look at things like coma and chromatic aberrations. At full open, for stars, the lens is fairly useless especially if using the built in astrotracer and the field rotation it suffers from. This turns the coma into some kind of awful aberration with this lens. It's best to shoot at f3.2 if you're going to use the 31mm ltd for astro. And yes, before people get on the case that 'astrotracer doesn't induce field rotation'... it does. I've documented it's affects very well. It happens with every lens I own and yet, while using the same settings and lenses, it doesn't happen at all on a proper tracking mount.


Astronomy photos, are in general pretty difficult for amateur photographers, for the reasons you listed, yours is still a great photo.
Very good Job.
Loris.
06-26-2023, 03:06 PM - 1 Like   #4
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I'm just starting down the road of astro photography and have found that all my lenses are improved by stopping down a little bit. The only exception I've found to this so far is the DFA85/1.4 which seems just fine wide open, but so far doesn't seem to be a great lens for this because of the field of view.

06-26-2023, 07:54 PM   #5
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QuoteOriginally posted by Wheatfield Quote
I'm just starting down the road of astro photography and have found that all my lenses are improved by stopping down a little bit. The only exception I've found to this so far is the DFA85/1.4 which seems just fine wide open, but so far doesn't seem to be a great lens for this because of the field of view.
Oh yes, most lenses need stopping down, there are a few unicorns that donít though. 85mm is a beautiful focal length for some deeper shots, especially if you live in an area where Rho Ophiuchi rises higher than 20deg. It wouldnít be great for much landscape stuff though. Even the 31mm on a crop sensor is pushing that aspect. I had to do a focus merge pa o for the foreground which was a huge challenge. Wind picked up just as I needed to start shooting my foreground. A couple spots look blurry not because of the focus stack but because of the wind.

I may do this same test with my Sky guider pro instead of Astrotracer just to eliminate that one variable making the stars look quite interesting in the corners.

---------- Post added 06-26-2023 at 07:57 PM ----------

QuoteOriginally posted by MikeNArk Quote
Clouds and light pollution are the banes of all astronomers. It looks like you were well positioned for shooting. Thanks for sharing your images.
They sure are Mike. Though in this situation my skies in my backyard are much darker. We couldnít even see the core naked eye here which is something I have no problem with at home. Just, home backyard doesnít support a nice foreground 😂

---------- Post added 06-26-2023 at 07:59 PM ----------

QuoteOriginally posted by loris nerozzi Quote
Astronomy photos, are in general pretty difficult for amateur photographers, for the reasons you listed, yours is still a great photo.
Very good Job.
Loris.
Thanks Loris yes, astrophotography is always a challenge whether Iím shooting DSO with my 1370mm telescope or doing a Milky Way, the challenges abound
06-26-2023, 08:25 PM - 1 Like   #6
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That first shot (of what looks to be mules ear sunflowers) is an image to be jealous of!
Wonderful image, in my perspective of the kind of images I like to try to get!!
Really wonderful shot!
Angky
06-27-2023, 09:03 AM   #7
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QuoteOriginally posted by angkymac Quote
That first shot (of what looks to be mules ear sunflowers) is an image to be jealous of!
Wonderful image, in my perspective of the kind of images I like to try to get!!
Really wonderful shot!
Angky
Thanks! They're Balsam Root flowers. They grow in large abundance in my area in May. The exact bloom date varies with elevation. While the lower hills had already bloomed and were on their way out, the upper hills were only just starting. I do quite like the image just annoyed with the clouds is all. If it had remained clear I would have got a lot more data. Hoping I get one more shot down south here in July's new moon before we head out for a month up north where I may not get astro dark even in August.

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