Large scale frustration

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KathyNS Canada
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Large scale frustration

#1

Post by KathyNS »


I've been itching for a couple of years to set up my C-11 for galaxy season. I was wanting a bit more image scale for little galaxies, planetary nebulae, etc. I had mounted it for the Mars-Moon occultation in December, which of course was clouded out, and we haven't had a clear night since then. With last night being clear and the daytime temperature being above freezing, I thought I'd get everything set up.

I had purchased an adapter that would allow me to mount my filter wheel and camera onto the OAG. Yesterday afternoon, I got that whole assembly put together, with approximate spacing, and mounted it onto the Moonlite focuser on the back of the C-11. To get the guide camera and imaging camera parfocal on the OAG, I aimed at a tree about 200 m away. It was an old oak tree, leafless of course at this time of year, and it wasn't moving too much in the wind.

I quickly realized that the FOV at that distance is about 5 cm! If there had been an ant crawling on one of those twigs, I could have told you the colour of its eyes. It took me a while - all twigs look alike - but I did manage to find a single leaf, which gave me something to align the finder on. I got the OAG dialed in approximately. Depth of field is about 2 cm, so it was a bit hard to tell if I had the same twig in focus in both cameras.

And, speaking of cameras, it was hard seeing anything in the daytime. With the guide camera shooting at 0.001 s and the imaging camera at 0.01 s, through the Ha filter (!) I was able to see the twigs.

Of course, I had some final focusing to do: finding infinity focus, and getting the OAG focus precise. So, after dark, I want out to do that. I was able to find Jupiter and use it to crank the focuser to infinity. That's a lot of turns on an SCT!

Then I had to get SGP set up. There are way more settings than I remembered that needed to be changed. I have a motor on the Moonlite, but it's a DC motor, not a stepper. (I didn't know about auto-focusing back when I bought it!) The FCUSB module that drives it has an "absolute position emulation" mode, but it is a bit dodgy. And it tries to drive the motor with USB power, which requires careful fiddling with the PWM pulse width and timing settings to make the motor turn at all. I quickly realized that autofocus wasn't going to work tonight, so I dug out my 11" Bahtinov mask and focused manually.

Then plate solving didn't work. Oh, another setting: "number of tries". I ask you, what kind of brain-dead default is 1? After a few hits on that, I figured that I was on target. Now guiding... Yes, I had already changed the focal length. But I knew I needed to recalibrate. Which requires seeing a star. Nopity-nope. There are precisely zero stars showing in the guide camera. It's an old QHY5, very noisy, and now it is looking through a pinhole and f/10 optics, instead of the f/3.2 optics it is used to.

By this time, I was getting chilled. Setting this thing up is just too much work. I need a better guide camera. I need to upgrade the motor in the Moonlite focuser. It is time to pull the plug on this experiment.

So I am thinking that, next warm day, I'll re-build my 8" Newt setup. If I need more image scale, I'll stick a barlow on it. :shifty: :violin:
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DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
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SkyHiker United States of America
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Re: Large scale frustration

#2

Post by SkyHiker »


Presumably you are accurately polar aligned in your observatory's fixed mount. So, if plate solving causes trouble, can't you just simply calibrate manually on one star? That should work for a scope that has no cone error (unlike a Newt where collimation can throw it off). Maybe I am wrong about cone error of SCTs. I know for my Newt it would not work that well. And once you are calibrated, can't you just park it and reuse it next time? I am kind of curious how your C11 would perform as opposed to a Newt with Barlow, which I would like to try some day on my 12" Newt.
... Henk. :D Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall, Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS, DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK, Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17", Website:Henk's astro images
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KathyNS Canada
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Re: Large scale frustration

#3

Post by KathyNS »


I think the plate solving problem came down to the Number of Tries = 1 item. I think it was on target in the end: I just had to re-start the plate solve three times. So finding objects and goto alignment are not issues.

As for guiding calibration, the guider has to see a star to calibrate (or guide). There are three problems using an OAG: the field of view is tiny, the OAG's FOV is outside that of the imaging camera, and the camera is old and very noisy. So even if I was lucky enough to have a star in the guide camera's FOV, it might not see it at f/10. If I knew exactly where the pick-off prism was relative to the imaging camera's FOV, I could maybe drive a bright star there by slewing the mount. But I don't, and that is a tedious process anyway. And it leaves the imaging camera off target by a non-reproduceable amount.

All the problems are solvable. After all, people do use SCTs for AP. But I'll have to throw more money and time at it. I'd rather just take pretty pictures.
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DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
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Gordon United States of America
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Re: Large scale frustration

#4

Post by Gordon »


I've had a few similar nights....

It's just going to take some work but the rewards should be worth the troubles!!!
Gordon
Scopes: Explore Scientific ED80CF, Skywatcher 200 Quattro Imaging Newt, SeeStar S50 for EAA.
Mounts: Orion Atlas EQ-g mount & Skywatcher EQ5 Pro.
ZWO mini guider.
Image cameras: ZWO ASI1600 MM Cool, ZWO ASI533mc-Pro, ZWO ASI174mm-C (for use with my Quark chromosphere), ZWO ASI120MC
Filters: LRGB, Ha 7nm, O-III 7nm, S-II 7nm
Eyepieces: a few.
Primary software: Cartes du Ciel, N.I.N.A, StarTools V1.4.

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JayTee United States of America
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Re: Large scale frustration

#5

Post by JayTee »


I know you have a .63 FR for the C11, are you using it? If not, why not? Granted it is one more accessory that can cause focusing issues, but it also may solve more than it creates. Thoughts?

I was just messing with my new guide camera in the CEM70G and it had an "auto" setting for exposure. Any number I input (to include 0.001) for exp duration gave me a solid white screen. When I ticked the box for the auto exposure, I immediately got a usable image. See if your camera has that option.

Cheers,
∞ 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°

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KathyNS Canada
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Re: Large scale frustration

#6

Post by KathyNS »


JayTee wrote: Mon Feb 13, 2023 10:15 pm I know you have a .63 FR for the C11, are you using it? If not, why not? Granted it is one more accessory that can cause focusing issues, but it also may solve more than it creates. Thoughts?

I was just messing with my new guide camera in the CEM70G and it had an "auto" setting for exposure. Any number I input (to include 0.001) for exp duration gave me a solid white screen. When I ticked the box for the auto exposure, I immediately got a usable image. See if your camera has that option.

Cheers,
Thanks for the suggestions. It was a worthwhile experiment to see what I still need to do to make that rig work. The big items are a new focus motor for the Moonlite, and a more modern guide camera. It is an old QHY5. Not a modern QHY5 with a bunch of letters after its name. This one is just Mr. QHY5. There is no auto exposure setting.

Point taken about the 0.63 reducer. That would make some of it easier. I'll throw it in next time.

For now, I have disassembled that rig and started reassembling the Newtonian rig. All mounted and balanced now. Next is cabling and collimation. Tomorrow night is supposed to be clear, so I'll give it a check-out session. I think that, for galaxy season, I will try out the 2" barlow that I have.
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DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
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Re: Large scale frustration

#7

Post by sdbodin »


I feel your frustration with the OAG. I ditched mine for this years galaxy run, using a long focus guide scope has worked very well, 1000mm guide with QHY5L-II, 2500mm scope thru Atik460ex. However I reduced exposures to 2 minutes vice 5 before and do more exposures to make up the total, guide goal is 2 seconds max. I think this has worked better on the experimental images so far and I will stick with it thru the gal season.

Nothing like plate scale for those pesky small galaxies,
Steve
Scopes; Meade 16 LX200, AT80LE, plus bunch just sitting around gathering dust
Cameras; Atik 460ex mono, Zwo ASI1600MC-cool, QHY5L-II color and mono
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Re: Large scale frustration

#8

Post by a100171 »


I can tell you first-hand that the Cold makes it all so much harder! Though we have had some warm days, it still gets pretty dang cold at night, and likely worse for you!

I setup my tripod on the night before (on a partly-cloudy night, and went through/tested a 2-star alignment just to know it was ready. By the time that was all done, I was chilled to the bone! But I needed to know the mount was working for the "forcasted" clear skies the next night. I don't think I would have gotten any imaging at all the next night if I did not have it ready.
When I was done for the evening, everything was getting quite frosty, from the PCs (laptops) to the tubes, etc. and that naturally included my hands.

That said, I did view a magnificent StarLink procession when setting up the mount...looking up in disappointment for how long it took to level/polar align, and OTA balance, with my hands warming-up in my pockets, it all happened right in front of me. Must have been Mag +1 or better. A real sight to see.
Meade 6", 8", and 10" SN, Meade 10" f/6.3 Lx200, ES ES-102, Meade 90mm DS-2000, Celestron CPC-800 HD, Celestron , AVX, CGEM-DX, Twilight I mounts. Omegon 2.1x 41mm Binocs.
Hyperstar for EdgeHD, ZWO and Celestron Nightscape CCD. A fully-functional Meade 12" RCX-400.
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Re: Large scale frustration

#9

Post by XCalRocketMan »


I had many issues with my OAG, but most were solved when I went with the ASI174mini(mm). The sensitivity of this camera allows me to find stars in almost every attempt since I purchased it a couple of years ago. Pricey for a dedicated guide camera but I can count on it when I finally get those rare clear skies.
Scopes Celestron EdgeHD-11; William Optics GT102; William Optics ZS61; Criterion Dynamax-8 SCT
Mounts AP1100GTO mount w/APCCpro; iOptron iEQ30 Pro; Criterion Dynamax-8 SCT
Lenses Hyperstar-III; Celestron 0.7x FR; WO Flat/Reducer 0.8x
Guiding Celestron OAG w/ASI174mm mini; WO 50mm; Orion ST80
Cameras and Filters ZWO2600mm Pro w/Optolong 3nm NB and RGB; ZWOASI1600mm Pro (ZWO LRGB and Astrodon Ha-5nm, Oiii-3nm, Sii-5nm), QHY10, Canon 50D; ASI174mm mini; ASI462MC; ASI120MC
Misc Moonlite focuser on Edge - Feather-Touch focuser on GT102; ZWO EAF on ZS61; ZWO 2" and 31mm FWs; Kendrick Dew System, Temp-est Fans
Software NINA; PHD; APT; BYE; PI; APP; PSP; Registax; FireCapture; SharpCap
Blog at: SkyAndRockets
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