Comparison of Rough Polar Alignment Methods

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tradesmith45 Senior Member • Posts: 2,130
Comparison of Rough Polar Alignment Methods

Have a couple small trackers - Sightron Nano Tracker & Vixen Polarie. Over the years have used different approaches to polar align these for starry landscapes using EQFL of 16 to 85mm & 135mm a couple times. Lacking confidence, I usually stick w/ 30" max exposure.

Like many of you, I wanted to polar align w/o craining my neck from below. Haven't seen tests of the numerous recommendations for each of these methods. Decided it was far past time to see which of these methods worked best:

  • Eyeballing Polaris and placing tripod/tracker pointing "correctly".
  • Compass & Inclinometer
  • Cell phone compass & inclinometer
  • Vixen Polariemeter compass & inclinometer
  • Cell phone planetarium app & center Polaris behind tracker
  • PS Align Pro app
  • Laser pointer mounted on tracker
  • Peep hole on tracker

I tested each of these by aligning the tracker then taking 8 consecutive 15" star images facing East using EQFL of 85mm (Fuji XF56mm). I stacked images sequentially in PS until trailing started. This gave me the longest usable exposure for each method.

Short version of the results are eye balling Polaris was as accurate as the first 6 of these & can gave 30" w/o trailing. The simply mounted laser pointer barely gave 45" w/o trailing.

Peep holes rock. Could get 1 to 2 minutes w/o trailing. The reasons most of these are inaccurate are simple.

Here's my old standard compass & inclinometer, Vixen Poalriemeter & DIY laser pointer mount.

All the approaches that use a compass are impacted by magnetic deflection from the tracker. I had hopped the Poalriemeter would be less sensitive because it set above the tracker but if you look closely below, it to is deflected 5-10º,

All the cell phone apps that use the compass are also deflected & inaccurate. Inclinometers - cell or physical - are accurate.

Because they do not point parallel to their axis, the laser pointer is inaccurate w/o an adjustable mount that can be sighted in. But that means you'll need a polar scope for tracker alignment for sighting in the laser:-D

Of course at shorter FL, all these alignment methods work reasonably well. But you can probably eyeball the alignment & use you phone angle meter to do as well as anything except for peep holes.

Hope this is helpful.

One last thing. Do have a polar scope for the Vixen. Bought an angle finder & adapter for it. Works ok but the high eye point of the angle finder doesn't show the whole FOV of the polar scope, reducing it by perhaps 1/3rd. That means as landscpaer1 found unless the tracker is already close to aligned, you'll have a hard time finding Polaris in the angle finder view.

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Alen K Senior Member • Posts: 1,073
Re: Comparison of Rough Polar Alignment Methods

Imagine that. Given that the peephole is built in to the Polarie, it's almost as if Vixen knew what they were doing.

I find it especially significant that a smartphone, which is essentially a fairly high-powered computer that can also make phone calls, is not as good as a zero-powered hole. So much for high technology.

Astrophotographer 10 Forum Pro • Posts: 13,812
Re: Comparison of Rough Polar Alignment Methods

Very helpful.

So the smartphone compasses are deflected by the Polarie? I thought they worked off GPS so they shouldn't be.

I do find the most accurate method with the Polarie is the polar scope. But as you say you need to set up the tripod so you can kneel behind it. The older polar scope does not have an illluminator. I got a Skywatcher one and its OK but does not really turn off.

I get up to 60 seconds at 14mm with smartphone inclinometer and compass.

I saw this wonderful feature on a prototype Toast Techonologies Polar alignment that used GPS and you simply adjusted the mount until a dot was in the centre of a circle it created. I haven't seen that come to market though.

Greg.

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OP tradesmith45 Senior Member • Posts: 2,130
Re: Comparison of Rough Polar Alignment Methods

Alen K wrote:

Imagine that. Given that the peephole is built in to the Polarie, it's almost as if Vixen knew what they were doing.

Yes! and our sore necks drive us to avoid the obvious & effective tool right in front of our face!

I've been curious about the new Slik ECH-630 tracker w/ a large & small peep hole. Wonder if the small one is usable & gives better alignment. The small hole on the Nano is harder to use than the Vixen.

I find it especially significant that a smartphone, which is essentially a fairly high-powered computer that can also make phone calls, is not as good as a zero-powered hole. So much for high technology.

Well just remember a Pole Master is also technology but purpose built. But this proves phone can't do everything - duh.

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swimswithtrout Veteran Member • Posts: 3,718
Re: Comparison of Rough Polar Alignment Methods

It takes less than 1 minute to use the polar scope in my little iOptron Skytracker to get it "as good as it gets" for 3 min subs at 80-100mm  focal length and 90% keepers.

If you're getting a crick in your neck...raise your tripod.

OP tradesmith45 Senior Member • Posts: 2,130
Cell Phones for Aligning Small Trackers

Cell phones use a solid state 3D compass.  GPS is used to get local magnetic declination corrections to give true north.  They are subject to magnetic deflection like all magnetic devices.

There are other challenges to the use of cell phones with small trackers - limited flat spaces to place the phone against.  The Nano is especially limited but the Polarie has short sides to use for placing a compass against.  These limit the reliability of compass readings.

The hollow drive shaft of the Polarie can be used w/ a planetarium app to check that Polaris shown on the app is centered in the middle of the shaft.  But this requires getting down on your knees & looking up.  Better to use the peep hole.  And the gyros in the cell phone are a bit sticky & may not always show Polaris in the correct location when the phone is placed against the drive.

Cheers,

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OP tradesmith45 Senior Member • Posts: 2,130
Re: Comparison of Rough Polar Alignment Methods

swimswithtrout wrote:

It takes less than 1 minute to use the polar scope in my little iOptron Skytracker to get it "as good as it gets" for 3 min subs at 80-100mm focal length and 90% keepers.

If you're getting a crick in your neck...raise your tripod.

Takes a little longer than that, 3-5 min., with my unilluminated scope on the Polarie. Have to place a red LED against a finger & position it correctly to see the reticule & Polaris. If I'm close to aligned, takes less than 1 min. for the peep hole even in red zone skies.

If I'm sore, getting up can take a bit-:)

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OP tradesmith45 Senior Member • Posts: 2,130
Re: Comparison of Rough Polar Alignment Methods

Astrophotographer 10 wrote:

Very helpful.

Thanks

So the smartphone compasses are deflected by the Polarie? I thought they worked off GPS so they shouldn't be.

See post on this.

I do find the most accurate method with the Polarie is the polar scope. But as you say you need to set up the tripod so you can kneel behind it. The older polar scope does not have an illluminator. I got a Skywatcher one and its OK but does not really turn off.

Do you find the SW illuminator can be dimmed enough to allow clear view of Polaris?  Did you find a US source?  Unfortunately postage from GB to USA is expensive for eBay sources.

I get up to 60 seconds at 14mm with smartphone inclinometer and compass.

That's what I'd expect for this FL.

I saw this wonderful feature on a prototype Toast Techonologies Polar alignment that used GPS and you simply adjusted the mount until a dot was in the centre of a circle it created. I haven't seen that come to market though.

Greg.

I'd expect a purpose built alignment system can be calibrated for magnetic deflection.

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Astrophotographer 10 Forum Pro • Posts: 13,812
Re: Comparison of Rough Polar Alignment Methods

tradesmith45 wrote:

Astrophotographer 10 wrote:

Very helpful.

Thanks

So the smartphone compasses are deflected by the Polarie? I thought they worked off GPS so they shouldn't be.

See post on this.

I do find the most accurate method with the Polarie is the polar scope. But as you say you need to set up the tripod so you can kneel behind it. The older polar scope does not have an illluminator. I got a Skywatcher one and its OK but does not really turn off.

Do you find the SW illuminator can be dimmed enough to allow clear view of Polaris? Did you find a US source? Unfortunately postage from GB to USA is expensive for eBay sources.

Yes it does but it does not attach that well to the Vixen Polar scope. The latest version of the Vixen Polar scope has a nice looking illuminator. But I don't want to have to buy another polar scope. Also I see a nice looking illuminator on a Japanese site. But they are hard to deal with, don't speak English well and slow to respond.

That's what I'd expect for this FL.

I saw this wonderful feature on a prototype Toast Techonologies Polar alignment that used GPS and you simply adjusted the mount until a dot was in the centre of a circle it created. I haven't seen that come to market though.

Greg.

I'd expect a purpose built alignment system can be calibrated for magnetic deflection.

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outlierrn Regular Member • Posts: 201
Re: Comparison of Rough Polar Alignment Methods

I've been using a folding 3 legged stool and photography tripod.  Setting the tripod height to match a comfortable seated position has make alignment rather painless.

OP tradesmith45 Senior Member • Posts: 2,130
Re: Comparison of Rough Polar Alignment Methods

outlierrn wrote:

I've been using a folding 3 legged stool and photography tripod. Setting the tripod height to match a comfortable seated position has make alignment rather painless.

I to have a 3 legged stool & have used it this way.  I worry I'll kick the tripod if I try to get up while seated so close.  So I prefer using a pad to kneel on for alignment and keep my chair away from the tripod.  But I have an old back/neck-:)

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outlierrn Regular Member • Posts: 201
Re: Comparison of Rough Polar Alignment Methods
1

tradesmith45 wrote:

outlierrn wrote:

I've been using a folding 3 legged stool and photography tripod. Setting the tripod height to match a comfortable seated position has make alignment rather painless.

I to have a 3 legged stool & have used it this way. I worry I'll kick the tripod if I try to get up while seated so close. So I prefer using a pad to kneel on for alignment and keep my chair away from the tripod. But I have an old back/neck-:)

Well, at 58, I'm not the oldest in the hobby, but move a lot slower than I used to.  Comfort helps me take my time with alignment.

Melgigg
Melgigg New Member • Posts: 11
Re: Comparison of Rough Polar Alignment Methods

I have been using a laser pointer on my Astrotrac for years, works really well.

https://youtu.be/wmGVv8GNOkQ

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Trollmannx Veteran Member • Posts: 6,712
Re: Comparison of Rough Polar Alignment Methods
1

Prefer to keep it simple.

Use the peephole and the polar finder on my Polarie here at 60N (Polaris is seen at quite a steep angle from here) and no problems (except bright summer nights just now).

Use the peephole only when using the 40mm lens and in a hurry, peep trough the the polar finder when a better alignment is wanted and when using the 105mm lens (that is my two wide angle astro lenses).

A feeble tripod often is the week link. Am served by a heavy duty and pretty high tripod that I got long ago (that is the advantage of paying a bit more to get a quality product - the tripod still serves me perfectly well after all those years).

OP tradesmith45 Senior Member • Posts: 2,130
Rigging & Rough Polar Alignment Methods

Trollmannx wrote:

Prefer to keep it simple.

Use the peephole and the polar finder on my Polarie here at 60N (Polaris is seen at quite a steep angle from here) and no problems (except bright summer nights just now).

Use the peephole only when using the 40mm lens and in a hurry, peep trough the the polar finder when a better alignment is wanted and when using the 105mm lens (that is my two wide angle astro lenses).

A feeble tripod often is the week link. Am served by a heavy duty and pretty high tripod that I got long ago (that is the advantage of paying a bit more to get a quality product - the tripod still serves me perfectly well after all those years).

Those are some hefty lenses. Presumably you use a counter weight of some kind with the Polarie?

One of the problems w/ small trackers is rigging them so the load stays centered rather than hanging far out to the side. That would be especially challenging w/ such big lenses. As you know, the Polarie heavy load kit gives balance around the drive axis but not around the Alt axis. So loads can shift out of alignment.

My payloads are never greater than 1.5 kg. It's reasonably easy to keep such loads centered over a tripod with the Nano or Polarie. Doing so makes it possible for me to successfully use small tripods in the Kg weight range. However, any type of pano head creates a tall stack that can increase torque even w/ just 1.5kg. payload.

Yes. 60º North would put some strain on ones neck and a tall tripod would help. I'm 45º North. When windy, I usually keep the tripod low & kneel to look through the peep hole.

For WA or UWA, shining a laser through the peep hole will give a Q&D alignment. But due to the dangers to aircraft, lasers should be used only briefly.

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EricTheAstroJunkie Contributing Member • Posts: 671
Re: Comparison of Rough Polar Alignment Methods

Fwiw I've used a compass and angle finder combo multiple times when I've shot in caves/blocked north view locations. It's tricky finding a spot where the compass is not reflected by the mount, but it's possible. I've managed 2 minute exposures with a 40mm lens (Sigma Art 40mm no less) with no trailing doing that method.

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nighthiker Regular Member • Posts: 325
Re: Comparison of Rough Polar Alignment Methods

Hi!

The laser pointer is very simple and good enough for 35mm and 30 sec frames. >=3 frames will also allow to get rid of plane & satellite trails by sigma clipping. Peephole seems to be better, but that's a pain in the back at 60N

At the moment we only have NLC here for which I don't need any tracker Next highlight are the Perseids which are right at the edge of astronomical darkness, so the show is quite short.

Any type of a pano head is a little bit much for the Nano Tracker, but for the Polarie I use a simple 'non-nodal indexed pano head' which helps a lot for multi-row panos at night. I just have to take care with any close foreground.

Trollmannx Veteran Member • Posts: 6,712
Re: Rigging & Rough Polar Alignment Methods

tradesmith45 wrote:

Trollmannx wrote:

Prefer to keep it simple.

Use the peephole and the polar finder on my Polarie here at 60N (Polaris is seen at quite a steep angle from here) and no problems (except bright summer nights just now).

Use the peephole only when using the 40mm lens and in a hurry, peep trough the the polar finder when a better alignment is wanted and when using the 105mm lens (that is my two wide angle astro lenses).

A feeble tripod often is the week link. Am served by a heavy duty and pretty high tripod that I got long ago (that is the advantage of paying a bit more to get a quality product - the tripod still serves me perfectly well after all those years).

Those are some hefty lenses. Presumably you use a counter weight of some kind with the Polarie?

Yes - got the original Vixen counterweight system (not cheap but works like a dream even in -30 C and the tracking is smooth when balanced).

The Polarie can handle the 40mm lens without a balancing system but all my images are equatorially oriented (north up, east to the left) and the balancing system makes finding and orienting the field much easier.

One of the problems w/ small trackers is rigging them so the load stays centered rather than hanging far out to the side. That would be especially challenging w/ such big lenses. As you know, the Polarie heavy load kit gives balance around the drive axis but not around the Alt axis. So loads can shift out of alignment.

My payloads are never greater than 1.5 kg. It's reasonably easy to keep such loads centered over a tripod with the Nano or Polarie. Doing so makes it possible for me to successfully use small tripods in the Kg weight range. However, any type of pano head creates a tall stack that can increase torque even w/ just 1.5kg. payload.

Agree - overloading any mount just lead to frustration and bad experiences.

Yes. 60º North would put some strain on ones neck and a tall tripod would help. I'm 45º North. When windy, I usually keep the tripod low & kneel to look through the peep hole.

For WA or UWA, shining a laser through the peep hole will give a Q&D alignment. But due to the dangers to aircraft, lasers should be used only briefly.

OP tradesmith45 Senior Member • Posts: 2,130
"Calibrated" Polariemeter+Inclinometer Best Rough Method for Sparing the Neck

Thanks for the replies Troll, Eric & Nighthiker. To me the conclusion of these tests is use the peep hole or polarscope to align the tracker once and find the correct deflected compass bearing on a Polariemeter. The inclinometer on those is too crude but cell phone or angle finders will do the job. So you strain your neck once to make the calibration & then use the Polariemeter/inclinometer going forward.

Yes laser pointers can work but no better than eyeball - unless your lucky. I've sometimes been able to get good 60" subs at 85mm but had trailing at 30" at 135mm using my DIY laser adapter. And its easier to rig a hot shoe to the Nano & some other small trackers to use a "calibrated" Poalriemeter than rigging a laser. Of course the Vixen has a hot shoe already.

Would have never expected the Polarie could handle the Sig 40mm beast w/o counterweights - an impressive little tracker.

FWIW, the Omegon LX3 is harder to adapt lasers or hot shoes to & it has steel components that deflect compasses. The LX2 had a peep hole instead of the polarscope on the LX3. I was able to find a rubber strip to wrap my laser pointer in & place it in the plastic clip but couldn't get it pointed correctly.

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Astrophotographer 10 Forum Pro • Posts: 13,812
Re: Comparison of Rough Polar Alignment Methods

tradesmith45 wrote:

swimswithtrout wrote:

It takes less than 1 minute to use the polar scope in my little iOptron Skytracker to get it "as good as it gets" for 3 min subs at 80-100mm focal length and 90% keepers.

If you're getting a crick in your neck...raise your tripod.

Takes a little longer than that, 3-5 min., with my unilluminated scope on the Polarie. Have to place a red LED against a finger & position it correctly to see the reticule & Polaris. If I'm close to aligned, takes less than 1 min. for the peep hole even in red zone skies.

If I'm sore, getting up can take a bit-:)

The Skywatcher polar scope illuminator works on the Polarie polar scope. Its a bit expensive for what it is but it works.

Greg.

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