Achieving focus with ASI 290 Guide and Orion ST80
- chris_g
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Achieving focus with ASI 290 Guide and Orion ST80
I'm missing the optics somehow here folks and am hoping someone can explain why I would not be able to achieve focus with the ZWO ASI 290MM guide without having to use a diagonal. I mean it works fine with the Orion 60mm, why is the 80ST different? I was able to achieve focus using an Orion correct image 1.25 diagonal, the only 1.25" I have. It did not use that much tube travel either to do it, so I figured I would have to go further out to achieve focus without the diagonal than with since it adds optical length. Or do I have this backwards, and I would. That didn't matter though, I couldn't foucs going full inward or outward, I also used the extension tube that came with it to give it more backward travel, no idea what I'm doing wrong or why a diaganol would work. However, I do believe that the diagonal messed with guiding.
Any insight would be appreciated.
Clear Skies,
Chris
Image OTA: EvoStar ED80, WO Z73, C8-A XLT
Mount: EQ6-R Pro Pier, AZ-EQ5 Pro Pier
Guide OTA: Orion 60mm, WO 32mm, ZWO OAG, SV501P
Guide Cam: ZWO 120mm, 290mm mini
EAA OTA: Orion ST80
EAA Cam: SVBony SV705C
EP: Baader Hyperion Modular Set
Filters: L-Pro Canon EOS C, L-eNhance, L-Pro, Optolong Ha 7mm, Optolong Oiii 6.5mm, Optolong Sii 6.5mm, ES H-Beta
Session Control: Mini PC/Win11 Pro, APT 4.1, PHD2 2.6.10
Processing: PixInsight, DSS 4.2.6, Adobe PS CC, Astronomy Tools Action Set, Star Spikes Pro
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Re: Achieving focus with ASI 290 Guide and Orion ST80
∞ 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 EQ6R, 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 ∞ AP Gear: ZWO EAF and mini EFW and the Optolong L-eXteme filter
∞ 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."
- chris_g
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Re: Achieving focus with ASI 290 Guide and Orion ST80
The tracking was consistently off by a few pixels in the same direction on each sub, guiding graph looked good. The diagonal is a correct image version so it would reverse and flip the image, drift right would be translated by PHD2 to drift left and up would be down. Or at least that's my thought process with the tracking. Probably have it all wrong, it calibrated fine. Something else comes to mind about that, the ST80 not being in close enough alignment with the C8 along the central axis would produce a similar error in guiding, the equivalent of inducing flexure. Or is that wrong too?
Below is a pic of about where the camera achieved focus with the diagonal that produced a good tracking graph with image shift. The next one is with a 20mm extension and the draw tube fully extended still no focus, more extension tubes? I've got one more, I'll try adding it next time out. But the optics isn't making sense to me. It just seems to far back and the camera should have achieved focus about 8.5 mm farther back from where it did with the diagonal, its working back focus distance is 8.5mm. Again, at least that is my thought process, is it wrong?
Image OTA: EvoStar ED80, WO Z73, C8-A XLT
Mount: EQ6-R Pro Pier, AZ-EQ5 Pro Pier
Guide OTA: Orion 60mm, WO 32mm, ZWO OAG, SV501P
Guide Cam: ZWO 120mm, 290mm mini
EAA OTA: Orion ST80
EAA Cam: SVBony SV705C
EP: Baader Hyperion Modular Set
Filters: L-Pro Canon EOS C, L-eNhance, L-Pro, Optolong Ha 7mm, Optolong Oiii 6.5mm, Optolong Sii 6.5mm, ES H-Beta
Session Control: Mini PC/Win11 Pro, APT 4.1, PHD2 2.6.10
Processing: PixInsight, DSS 4.2.6, Adobe PS CC, Astronomy Tools Action Set, Star Spikes Pro
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Re: Achieving focus with ASI 290 Guide and Orion ST80
First off, never image or guide through a diagonal if you can at all help it. Also, your guiding axis being off from your imaging axis induces what's called "cone error". A small cone error (<5°) is almost never noticeable. A larger cone error, say greater than 20-30° takes a lot of exposure time before you do notice it.chris_g wrote: ↑Mon Dec 19, 2022 3:43 am The tracking was consistently off by a few pixels in the same direction on each subs guiding graph looked good. The diagonal is a correct image version so it would reverse and flip the image, drift right would be translated by PHD2 to drift left, and up would be down. Or at least that's my thought process with the tracking. Probably have it all wrong, it calibrated fine. Something else comes to mind about that, the ST80 not being in close enough alignment with the C8 along the central axis would produce a similar error in guiding, the equivalent of inducing flexure. Or is that wrong too?
My
∞ 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 EQ6R, 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 ∞ AP Gear: ZWO EAF and mini EFW and the Optolong L-eXteme filter
∞ 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."
- bobharmony
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Re: Achieving focus with ASI 290 Guide and Orion ST80
Bob
Software: BYE, APT, PHD2, DSS, PhotoShop CC 2020, StarTools, Cartes du Ciel, AstroTortilla
- chris_g
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Re: Achieving focus with ASI 290 Guide and Orion ST80
Wow, okey dokey then, more extension tubes... I tried not guiding through the diagonal but when I couldn't get focus, I brought out it out with an 10mmJayTee wrote: ↑Mon Dec 19, 2022 9:43 amFirst off, never image or guide through a diagonal if you can at all help it. Also, your guiding axis being off from your imaging axis induces what's called "cone error". A small cone error (<5°) is almost never noticeable. A larger cone error, say greater than 20-30° takes a lot of exposure time before you do notice it.chris_g wrote: ↑Mon Dec 19, 2022 3:43 am The tracking was consistently off by a few pixels in the same direction on each subs guiding graph looked good. The diagonal is a correct image version so it would reverse and flip the image, drift right would be translated by PHD2 to drift left, and up would be down. Or at least that's my thought process with the tracking. Probably have it all wrong, it calibrated fine. Something else comes to mind about that, the ST80 not being in close enough alignment with the C8 along the central axis would produce a similar error in guiding, the equivalent of inducing flexure. Or is that wrong too?
MyES 80mmAPO needs 6" of spacers for the sensor to come into focus. It looks goofy as all get out. But hey, you do what it takes.
As always, thanks the enlightenment.
Clears Skies,
Chris
Image OTA: EvoStar ED80, WO Z73, C8-A XLT
Mount: EQ6-R Pro Pier, AZ-EQ5 Pro Pier
Guide OTA: Orion 60mm, WO 32mm, ZWO OAG, SV501P
Guide Cam: ZWO 120mm, 290mm mini
EAA OTA: Orion ST80
EAA Cam: SVBony SV705C
EP: Baader Hyperion Modular Set
Filters: L-Pro Canon EOS C, L-eNhance, L-Pro, Optolong Ha 7mm, Optolong Oiii 6.5mm, Optolong Sii 6.5mm, ES H-Beta
Session Control: Mini PC/Win11 Pro, APT 4.1, PHD2 2.6.10
Processing: PixInsight, DSS 4.2.6, Adobe PS CC, Astronomy Tools Action Set, Star Spikes Pro
- chris_g
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Re: Achieving focus with ASI 290 Guide and Orion ST80
Mine will be used primarily forbobharmony wrote: ↑Mon Dec 19, 2022 2:41 pm For my ST-80 and Orion StarShoot autoguider, I use an extension tube in the drawtube to get the camera into focus. Not the best for stability and I have tried to figure out how to support the entire train without success so far.
Bob
Clear Skies,
Chris
Image OTA: EvoStar ED80, WO Z73, C8-A XLT
Mount: EQ6-R Pro Pier, AZ-EQ5 Pro Pier
Guide OTA: Orion 60mm, WO 32mm, ZWO OAG, SV501P
Guide Cam: ZWO 120mm, 290mm mini
EAA OTA: Orion ST80
EAA Cam: SVBony SV705C
EP: Baader Hyperion Modular Set
Filters: L-Pro Canon EOS C, L-eNhance, L-Pro, Optolong Ha 7mm, Optolong Oiii 6.5mm, Optolong Sii 6.5mm, ES H-Beta
Session Control: Mini PC/Win11 Pro, APT 4.1, PHD2 2.6.10
Processing: PixInsight, DSS 4.2.6, Adobe PS CC, Astronomy Tools Action Set, Star Spikes Pro
- chris_g
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Re: Achieving focus with ASI 290 Guide and Orion ST80
Clear Skys,
Chris
Image OTA: EvoStar ED80, WO Z73, C8-A XLT
Mount: EQ6-R Pro Pier, AZ-EQ5 Pro Pier
Guide OTA: Orion 60mm, WO 32mm, ZWO OAG, SV501P
Guide Cam: ZWO 120mm, 290mm mini
EAA OTA: Orion ST80
EAA Cam: SVBony SV705C
EP: Baader Hyperion Modular Set
Filters: L-Pro Canon EOS C, L-eNhance, L-Pro, Optolong Ha 7mm, Optolong Oiii 6.5mm, Optolong Sii 6.5mm, ES H-Beta
Session Control: Mini PC/Win11 Pro, APT 4.1, PHD2 2.6.10
Processing: PixInsight, DSS 4.2.6, Adobe PS CC, Astronomy Tools Action Set, Star Spikes Pro
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