Widefield MW Dust in Scutum

CCD vs Film? Lots of time vs no patience? Alright, this is your place to discuss all the astrophotography what's and what's not. You can discuss about techniques, accessories, cameras, whatever....just make sure you also post some nice photos here too!
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rss1234
Posts: 15
Joined: Sat May 22, 2021 1:46 pm
Favourite scope: William Optics GT71

Widefield MW Dust in Scutum

Post by rss1234 »

I decided to visit a star-dense area to test my new Samyang 85mm lens. If I'm not wrong, I used f/3.6 for 6 hours on this image because at faster focal ratios the stars were of very poor quality. Overall I am quite happy with the star shape and colour, I used a ZWO UV/IR cut filter to help subdue bloated stars but ended up with a slight purple tint on brighter stars. Thankfully I could fix this in post-processing.

On the processing side of this image, multiple new techniques have been developed such as Multiscale Gradient Removal (MSGR), independent starless processing by removing stars while the image is linear using Starnet2, and specialised AI noise reduction using NoiseXterminator. Stretching was done with Generalised Hyperbolic Stretch (GHS) and a touch of histogram/curves adjustment.

Even though the corner stars are not great, I am still happy with how this test image turned out.

ASI 533MC Pro, Samyang 85mm f/3.6, AVX, captured from Singapore

Image
hhzhang
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Re: Widefield MW Dust in Scutum

Post by hhzhang »

Full of stars!
A 6-hour total exposure test sounds a little insane :) And the data processing procedure is quite sophisticated. If it does not involve paid software, I hope can learn from you.

Given 533 is a small-size 1-in sensor, what actually caused the obvious aberrations only in the upper part (most prominently in the upper-right corner) even in this small image? Could it be some misalignment of the optics or the flange and sensor planes?

I am also a little obsessed with pinpoint , tack sharp star images!
rss1234
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Joined: Sat May 22, 2021 1:46 pm
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Re: Widefield MW Dust in Scutum

Post by rss1234 »

hhzhang wrote: Wed Jul 27, 2022 11:22 am Full of stars!
A 6-hour total exposure test sounds a little insane :) And the data processing procedure is quite sophisticated. If it does not involve paid software, I hope can learn from you.

Given 533 is a small-size 1-in sensor, what actually caused the obvious aberrations only in the upper part (most prominently in the upper-right corner) even in this small image? Could it be some misalignment of the optics or the flange and sensor planes?

I am also a little obsessed with pinpoint , tack sharp star images!
The corner stars are far from perfect and I suspect that it is because my camera sensor is not perfectly aligned with the focus plane. That results in me needing to adjust tilt manually, so I had to slide in some folded pieces of aluminium foil in between the camera and extender ring, but I only did this on the last night of imaging so the integrated image still has the elongated corner stars.

All the processing is done within Pixinsight, and all of these are free with the exception of NoiseXterminator. However, for this image I used the free trial of it, but I will be purchasing it soon.
rifleman175
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Re: Widefield MW Dust in Scutum

Post by rifleman175 »

Great shot considering the severe light pollution here in Singapore! By the way I can definitely vouch for NoiseXterminator, it simply works like magic!
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