Image Quality and the need for stacking

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StarTravel
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Image Quality and the need for stacking

#1

Post by StarTravel »


I wanted to canvass opinions, or at least to get a view as to how people are using 'stacking' for lunar shots these days.

I'm looking to achieve the best possible image quality using eyepiece projection with my 500mm Star Watcher and my Nikon D850: perhaps not the finest 'scope(!) but an awesome camera as I'm more a photographer than an astronomer - at the moment at least.

First question... I'm attaching the best image I could make of the Sturgeon Full Moon. What do people think of this, is it reasonable given the telescope I'm using (it has no field flattener and doesn't even have ED glass I don't think) or should it be possible to do better with my kit? Is it any good???
20220812-sturgeon-supermoon-v2.jpg
The second question is all about lunar stacking, which I haven't had success with yet (the above is a single frame). I've tried shooting hundreds of frames (as all the videos say that's what is needed) but I can't get a successful stack. I think this is because shooting frame by frame takes a long time and the rotation of the moon fouls the software. I don't want to record video as that limits the image size to around 2000px diameter for the moon (at 4K). I have over 5000px on my sensor so I want to create a lunar image of that size!

I'm shooting at ISO 1600 (the camera's native top ISO is 25,600), using dark frames and registax6. So I think the noise is well handled which leaves me wondering if I really need lunar stacking at all!?? But does stacking also help in managing 'fluctuation in the atmosphere'? Irrespective of the noise question, would stacking improve the image quality? If so, which PC software is best for it when shooting full-frame high resolution (46MP) images?

In Summary
1. What quality can I expect, is the attached image decent or not?
2. Is stacking even needed?
3. Is Autstakkert! the software to use in this scenario??

Many thanks in anticipation of my fellow astrophotgraphers' thoughts and ideas

Kind Regards
Ant
see my website: https://antsmith.net
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Lady Fraktor Slovakia
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Re: Image Quality and the need for stacking

#2

Post by Lady Fraktor »


Hello Ant,
Exactly what telescope are you using?
The image is nice though others who do imaging will have to supply comments with stacking and such.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
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Re: Image Quality and the need for stacking

#3

Post by JayTee »


This post is being moved to the most appropriate Forum (AP Image Processing) where it will get a much better response.
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
∞ Mounts: iOptron CEM70AG, SW EQ6, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000
∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3
∞ Binos: 10X50,11X70,15X70, 25X100
∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°

Searching the skies since 1966. "I never met a scope I didn't want to keep."

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StarTravel
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Re: Image Quality and the need for stacking

#4

Post by StarTravel »


Thank you for moving the post!

Re telescope it’s a Sky Watcher Star Travel 102D - 500mm f/5 refractor.
see my website: https://antsmith.net
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AstroBee United States of America
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Re: Image Quality and the need for stacking

#5

Post by AstroBee »


The problem with astrophotography with a DSLR is something called mirror slap. For regular photography it is not noticable because you are shooting and much shorter focal lengths (magnification) and generally faster shutter speeds. When shooting astrophotography like this, even with a very sturdy mount and using a cable release or timer to trigger the shutter, there's still a slight bit of vibration caused by the mirror when it flips up and "slaps" the prism. That can make a perfectly tracked and focused image appear like yours, very slightly blurry. Two ways around this are to shoot video as you've already mentioned or use mirror lock-up if your DSLR offers that feature. Mirror lockup will first flip the mirror out of the way, then you wait a couple of seconds for the vibration to settle and trigger the shutter with a second press of the cable release.
Shooting video is really the way to go. You shoot at say 30fps for a minute or two and use a program like AutoStakkert to separate those individual frames (30fps x 60sec) 1800 frames, and the software analyzes each frame and selects the very best to make your final image.

All things considered though, it's a fine first lunar image to be proud of. For simple lunar imaging like this, a flattener and ED glass are NOT necessary.
Greg M.~ "Ad Astra per Aspera"
Scopes: Celestron EdgeHD14", Explore Scientific ED152CF & ED127 APO's, StellarVue SV70T, Classic Orange-Tube C-8, Lunt 80mm Ha double-stack solar scope.
Mounts: Astro-Physics Mach One, iOptron CEM70EC Mount, iOptron ZEQ25 Mount.
Cameras: ZWO ASI2600mm Pro, ZWO 2600MC Pro, ZWO ASI1600mm
Filters: 36mm Chroma LRGB & 3nm Ha, OIII, SII, L-Pro, L-eXtreme
Eyepieces: 27mm TeleVue Panoptic, 4mm TeleVue Radian, Explore Scientific 82° 30mm, 6.7mm , Baader 13mm Hyperion, Explore Scientific 70° 10mm, 15mm, 20mm, Meade 8.8mm UWA
Software: N.I.N.A., SharpCapPro, PixInsight, PhotoShop CC, Phd2, Stellarium
https://www.nevadadesertskies.com
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