What happens if you use an equatorial mount without polar aligning it?

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UnityLover
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What happens if you use an equatorial mount without polar aligning it?

#1

Post by UnityLover »


Im wondering, what happens if you use an equatorial mount without polar aligning it?
Just asking.
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Juno16 United States of America
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Re: What happens if you use an equatorial mount without polar aligning it?

#2

Post by Juno16 »


For visual use or astrophotography?
Jim

Scopes: Explore Scientific ED102 APO, Sharpstar 61 EDPH II APO, Samyang 135 F2 (still on the Nikon).
Mount: Skywatcher HEQ5 Pro with Rowan Belt Mod
Stuff: ASI EAF Focus Motor (x2), Orion 50mm Guide Scope, ZWO 30 mm Guide Scope, ASI 220mm min, ASI 120mm mini, Stellarview 0.8 FR/FF, Sharpstar 0.8 FR/FF, Mele Overloock 3C.
Camera/Filters/Software: ASI 533 mc pro, ASI 120mm mini, Orion SSAG, IDAS LPS D-1, Optolong L-Enhance, ZWO UV/IR Cut, N.I.N.A., Green Swamp Server, PHD2, Adobe Photoshop CC, Pixinsight.
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Re: What happens if you use an equatorial mount without polar aligning it?

#3

Post by AstroBee »


It will not track the sky correctly. No damage will come to the mount unless you kick the mount over out of frustration for it not working properly. :D
For visual use, a rough polar alignment is really all you need. For imaging, the closer to perfect, the better.
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
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Re: What happens if you use an equatorial mount without polar aligning it?

#4

Post by SkyHiker »


Imagine 2 spheres rotating at the same speed around slightly different axes. If you rotate along with one sphere you will see the axis of the other sphere wiggle around the reference axis in 24 hours. One sphere, of course, would be Earth and the other the sky.

If the axes are off by an angle dTheta arc minutes, then the global worst-case error is 2*dTheta arc minutes (= 120* dTheta arc seconds) in 12 hours, or dTheta*10 arc seconds per hour. For AP star trails of 1 arc second can be a problem, so if the PA is off by 1 arc minute, the limit is 6 minutes (worst case). This depends on how bad the error is relative to all others, and also depends on the optical parameters.
... 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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Re: What happens if you use an equatorial mount without polar aligning it?

#5

Post by JayTee »


It will be the worst Alt-Az mount you've ever used!

Cheers,
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
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Re: What happens if you use an equatorial mount without polar aligning it?

#6

Post by UnityLover »


@Juno16
Mainly visual, but some photography of planets and the moon.
Will do many 10 second exposures for nebulae, but I will polar align if I do that.
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Re: What happens if you use an equatorial mount without polar aligning it?

#7

Post by SkyHiker »


First off, imaging planets and nebulae are very different.

For planets, large aperture is needed to get good resolution because of Dawes' limit. There is no workaround for this physics-imposed limit. Think 10" to 14" diameter. It is done with lucky imaging, meaning that you take video at high frequency (100 Hz or more) and have a program named Autostakkert to sort the best images and stack them.

For nebulae, accurate tracking is crucial. Accuracy requirements can be relaxed as the field becomes wider. If you want a cheap solution, build a barndoor drive for $20 or so (stepper motor, Arduino, some boards, and a stable camera tripod that you hopefully have). We can help you with that. A barndoor is a cheap DIY version of commercially sold "star trackers", and it can be a fun way to start and get some nice images for up to 300 mm focal length.

With the $120 worth of gear that you intend to buy, any attempt at AP is futile. It will just be a miserable frustrating experience, if you are after nice images. If you want to experience the pitfalls to understand the limitations in the face of failure, that can be a hobby in itself too. I am kind of like that myself and have experimented a lot, for me it is part of the fun.
... 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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Richard South Africa
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Re: What happens if you use an equatorial mount without polar aligning it?

#8

Post by Richard »


Well you are in the northern hemisphere so its quite simple to align an EQ mount if you can see Polaris , its ok not great but for visual and short exposures as long as the mount has a tracking motor , you could track manually but its hard , I only use a GO TO alt az mount for short exposures which are ok but its mainly planets and after a few years I gave up , so now mainly visual
AP is expensive even now certainly easier with digital but not for everyone
Reflectors GSO 200 Dobs
Refractors None
SCT C5 on a SLT mount
Mak 150 Bosma on a EQ5
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Juno16 United States of America
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Re: What happens if you use an equatorial mount without polar aligning it?

#9

Post by Juno16 »


UnityLover wrote: Wed Sep 07, 2022 10:03 pm @Juno16
Mainly visual, but some photography of planets and the moon.
Will do many 10 second exposures for nebulae, but I will polar align if I do that.

Visual is very rewarding and fun. It is a great way to really appreciate the night sky and what things look like. It is really a kick to see things in real time.
Astrophotography can be as simple as a cell phone.

Take it slow and enjoy!
Jim

Scopes: Explore Scientific ED102 APO, Sharpstar 61 EDPH II APO, Samyang 135 F2 (still on the Nikon).
Mount: Skywatcher HEQ5 Pro with Rowan Belt Mod
Stuff: ASI EAF Focus Motor (x2), Orion 50mm Guide Scope, ZWO 30 mm Guide Scope, ASI 220mm min, ASI 120mm mini, Stellarview 0.8 FR/FF, Sharpstar 0.8 FR/FF, Mele Overloock 3C.
Camera/Filters/Software: ASI 533 mc pro, ASI 120mm mini, Orion SSAG, IDAS LPS D-1, Optolong L-Enhance, ZWO UV/IR Cut, N.I.N.A., Green Swamp Server, PHD2, Adobe Photoshop CC, Pixinsight.
Dog and best bud: Jack
Sky: Bortle 6-7
My Astrobin: https://www.astrobin.com/users/Juno16/
UnityLover
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Re: What happens if you use an equatorial mount without polar aligning it?

#10

Post by UnityLover »


@Juno16
Thats exactly what I was thinking! Using a cell phone to snap some very simple, barely colored photos, I dont expect much, just something similar to this photo of the orion nebula: https://www.cloudynights.com/gallery/im ... ebula-m42/
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