Alinging a Vixen Polarie

[Hakka]

I just did a quick test shoot with the polarie. I'm having a bit of trouble getting the alignment right. I can't see Octans, I ended up just pointing it in the general direction of where I thought it was. I'm north of melbourne (bendigo) which puts octans in the light pollution from melb.

I was getting good shots up to about 2 minutes but after that I the stars were starting to trail.

Just wondering what other options there are for aligning this thing, is there any way of doing it using a laptop + software? I have a D800E and can feed a HDMI signal to my laptop.

I'm guessing the scope wont be much use due to the light pollution.

I'd like to get my exposures out to around 8 minutes so I can shoot the milky way at base iso for some very large prints, I really need the alignment to be perfect.

Thanks.

[2stroke]

Seems like a dumb thing to buy for the southern hemi lol, Try a dark site where you can get the polar scope to work, can you tweek the polar scope brightness if its lite? Maybe the solar noon method could help if you got alt correctly set. I would sell it and get a eq5 with RA tracking motor if tight for money or a eq3 with goto and use alignmaster.

[Hakka]

I dont have the polar scope, not really sure how the scope works, never seen one.

[iceman]

Are you serious? What a ridiculous comment to make.

Have you seen or used one?

They're in a completely different league than a tracking mount. Different purpose.

[iceman]

What focal length were you using? 2 minutes is pretty good!

I was getting 2 minutes with a wide field of view after just using a compass to roughly align it south and trying to set the latitude adjustment as accurate as possible.

http://www.mikesalway.com.au/tag/vixen-polarie/

[Hakka]

I was using 14mm. There's not much trailing so it was pretty close, i had to zoom right in to see it. It would be noticeable on a 60 inch print though.

I aimed it using crux and the small mag cloud. I'm assuming its possible to get no trailing at 14mm and about 6 to 8 minutes?

Nice pics mate.

[naskies]

Welcome, Lincoln! I think you're the guy famous for those beautifully colourful star trails images (http://images.google.com/search?hl=en&site=&tbm=isch&source=hp&biw=960&bih=1102&q=lincoln+harrison), right? If so - great work!

The two main culprits for trailing are usually (1) polar misalignment, and/or (2) flexure of your tripod, mount head, etc.

When I used an Astrotrac mount (similar to a Polarie but slightly beefier), I used drift alignment with LiveView to tweak the polar alignment. I was able to take 3 min exposures @ 135 mm (6.4 um pixels) without star trailing. However, you'd need a very stiff tripod - otherwise it flexes when you point the camera elsewhere in the sky, ruining the polar alignment - and a wedge/geared head that lets you tweak altitude/azimuth separately for drift alignment.

Here's an example of a single-shot Milky Way that I took last year: 15 min with a Canon 5DmkII + 14 mm f/2.8L @ f/8 ISO 1600.

http://www.iceinspace.com.au/forum/showthread.php?t=92443

By the way, if your aim is to create a very high resolution panorama of the Milky Way, you'll get much better results by stitching together lots of panels - each shot by stacking many individual photos together. Here are two of the best Milky Way panoramas that I've ever seen:

http://sguisard.astrosurf.com/Pagim/GC.html
http://skysurvey.org/about/

Broadly speaking, shooting at ISO 100 on a DSLR won't get you as good a result as stacking multiple higher ISO shots of equal/longer duration because there will be more thermal noise, more read noise, stars will bloat and lose their colour from individual pixels being over-saturated, and if you're shooting very wide field - you may run into problems with air glow and atmospheric refraction.

Just as a comparison, here are a few images that I shot just a few weeks before the Milky Way at 135 mm - you'll see that they're much richer with the stacking:

http://www.iceinspace.com.au/forum/showthread.php?t=91077

Anyway, please take this with a grain of salt... I barely know what I'm doing :lol: Good luck!

[luigi]

Hi Lincoln,

The Polarie is a fantastic unit, I will help you align it and believe me you can go to 4, 5, 8, 10 minutes exposures. I recently did 5 minutes 90mm without problems.

You need a method to find the octans trapezium. And it works under light pollution!!

I always start with Beta Hydri which is a bright star next to the SMC. You can certainly find it with the naked eye and put it in the polarscope. Use Achernar if needed as a reference.

From Beta Hydri you move to 3 stars with the shape of a little arrow and they point to the octans trapezium. (see the attachment map)

Please remember that the location of the 3 stars relative to Beta Hydri changes as they rotate around the celestial pole but you can always get both Beta Hydri and the 3 stars in the polarscope field of view so you know where to go. The arrow always points to the trapezium.

Once you have the trapezium located use a small red led light to illuminate the polarscope and place the trapezium exactly in the position indicated by the reticle. Then just enjoy, the polarie is really precise.

[Hakka]

Dave, Yep that's me :)

I'm using a gitzo 3532 tripod with manfrotto 405 geared head, its a pretty solid setup.

I'm aiming for night landscapes rather than hi res astro shots, here's one i took before i got the mount:

http://500px.com/photo/27033009

I'll give the stacking a go, it works well for the startrail shots.

Luigi, i dont have the polar scope, i was looking through the main hole and the the small hole (which seems useless). I'll order the scope today, in the meantime i'll have a go at drift alignment.

I've been looking at a shot i took of the sky around the pole and i've made a star map thing which should help, looks similar to your pic. Also ordered an inclinometer.

Thanks guys.

[naskies]

Aah, I think *some* trailing will be unavoidable with long exposures due to atmospheric refraction, i.e. the stars near the horizon appear to move at a different speed to stars high in the sky.

Is it trailing across the entire frame? Perhaps you could post some crops?

[Hakka]

Its not as bad near the pole as it is to the east, but its pretty even top to bottom. I'll post some crops this arvo, i'm not near my pc at the moment.

[gregbradley]

Stunning photos. I look forward to seeing your posted images they are amazing. I am using a D800E and 14-24mm also.

Another approach is the drift alignment method.

Here is what I have been doing but it would be slower than the great advice from Luigi below.

Get the tripod and Polarie level using bubble levels.
I use a longish lens like 180mm F2.8.
I get the altitude right using a digital inclinometer I bought off ebay for $25 or so. It can be a tad tricky to use it as the Polarie has rounded edges on the body so getting the inclinometer square on the body needs to be done carefully. I adjust the altitude to match the latitude.

Now I aim it south using my knowledge of where the SCP is - I orient off the Magellanic Clouds and Achenar. Or use the compass for a rough orientation.

Take a 10 second shot, look at the image it most likely will show star trailing. Adjust the mount east or west, it does not matter which. Take another shot - is star trailing better or worse? If better then the first adjustment was in the right direction - do a bit more. If worse you need to adjust the opposite way so do that. Take another shot - better or worse? adjust accordingly. Keep this up. After about 4 or 5 adjustments you will be getting roundish stars. How long you keep this up is up to you. It also assumes you did a good job on setting the altitude. So if you are getting nowhere then check that again.

I find I can get round stars at 180mm for 60 seconds after about 6 minutes or so of the above procedure.

The Polar scope would be better.

There is also an accessory for the Polarie which is a built in compass and inclinometer that attaches to the hot shoe. It would be very handy and costs about $70.

Greg.

[2stroke]

Well that's asking alot for alignment with light polluted skies don't you think, maybe they should have made the polar scope with a wider view to aid alignment in the southern hemi. Seems like a real biased setup for the northern hemi, i'am not knocking its features and usage just its alignment procedure so yes i stand by that comment. Its great that someone has posted back his alignment procedure, maybe they should included this in there documentation. If there was no way you could align one would you still buy one? Also no i haven't used one or even seen one, though if you were paying ~$500 for 2 minutes it would want to mow your lawns in its spare time.

[Hakka]

Here's some examples, the full image and a 100% crop from near the middle.

This one was 300 seconds iso800 f2.8.

I had a closer look at all the shots I took, this was the closest I got it to the pole, a 2 minute exposure with the same alignment doesn't show trailing.

I've just ordered the polar scope. If its clear skies tonight I'll have a go at drift aligning.

edit: I've just realised if I shoot a startrail on the winter solstice and run the polarie in northern hemisphere mode I should get 360 degree trails!!

[CapturingTheNight]

Hi Lincoln. Great to see you here. Been a big fan of yours ever since I found you over on 500px. I have had the same thought with running the mount backwards and getting longer trails for the time, but it would only work close to the celestial pole and you couldn't have any terrestrial elements in the field of view.
Cheers
Greg

[multiweb]

I use mine from home at the junction of the M7 and M5 in western Sydney so pretty bad LP. Never had a problem aligning. There is an inclinometer and a compass for this. No need for a polar scope.


It works fine in the SH. There is an internal switch so it tracks both ways.


Lot of info on various forums and youtube on how to polar align the unit. It's everywhere and has been for a while.


That's where you're wrong. Although it's not a substitute for a mount you can do very long exposures with a DSLR without trailing. I did 7min at Coonabarabran with a 50mm lens. At 200mm you will need to be fairly well polar align or you'll see trailing in excess of 1min subs.

Best $400 I've spent. TBH I use it all the time and take it with me everywhere I go.

[Hakka]

I dont have my polar scope yet but i just had some success using a pair of binoculars pressed up against the scope mounting hole, 5 minutes at 24mm and zero trailing.

Its a lot easier when you can actually see octans.

Greg, yeah I thought about the issues with the 360 degree trails but i think i could work around them in photoshop reasonably easily. Its cheating but its the only way i'll get 360 degress without going to antarctica :)

[gregbradley]

I always start with Beta Hydri which is a bright star next to the SMC. You can certainly find it with the naked eye and put it in the polarscope. Use Achernar if needed as a reference.

From Beta Hydri you move to 3 stars with the shape of a little arrow and they point to the octans trapezium. (see the attachment map)

Please remember that the location of the 3 stars relative to Beta Hydri changes as they rotate around the celestial pole but you can always get both Beta Hydri and the 3 stars in the polarscope field of view so you know where to go. The arrow always points to the trapezium.

Once you have the trapezium located use a small red led light to illuminate the polarscope and place the trapezium exactly in the position indicated by the reticle. Then just enjoy, the polarie is really precise.[/QUOTE]


Hey Luigi,

Thanks a million for posting this. I had given up on using the Polar scope but I used this on the weekend and it was really easy at my dark site. I could get the unit really well aligned in about 8 minutes. No trailing at 90 seconds and 180mm.

I need to put some tape or something over my torch as the main difficulty I had was my torch was overwhelmingly bright when illuminating the reticule.

The instructions about the polar scope regarding the date, hour, level etc are exceedingly sparse and hard to understand. Then I realised you don't even need any of that. You simply find the trapezium and then rotate the reticule to match it. Not sure why they put all that other date/hour stuff on it.

Greg.

[seeker372011]

Luigi and you, Greg, make a strong case to invest in the polar scope....or lfor a little more money just buy the Ioptron version which comes with a polar scope..

Last night I was all set up and still trying to polar align when the cloud came over...from the sound of it,you were away and imaging in a few minutes

[naskies]

Nice effort! Another IIS member (rogerg) fitted a laser pointer to his AstroTrac to help with polar alignment. I wonder if that would be possible with the Polarie?

http://rogergroom.com/astronomy-resources/my-astronomy-and-photographic-equipment/astrotrac-portable-telescope-mount/attachment/001267/

[Hakka]

I was thinking about trying that too but i cant find my laser pointer. I'm not sure if the one i have would be powerful enough.

[naskies]

If it's green then it probably would be from a dark site. My 10 mW green laser is very visible in suburbia - almost blindingly bright from a dark site.

[Lester]

I align my polarie with phone apps, compass and inclinometer and have been able to take 1 minute exposures with 200mm lens okay.

[gregbradley]

Green laser would be helpful except for the same problem of the SCP isn't really a visible location and Sigma Octans, at least for me, is impossible to locate visually with any certainty. If you know you way around visually then yeah I can see that being helpful.

If I couldn't get the polar scope to work (not sure how it would work in light polluted areas as some of those stars are still pretty dim)
then I'd get that accessory with the inclinometer and compass or as Lester pointed out using iphone apps. And then drift align it to improve on that result if you want to use a longer focal length lens. Drift aligning is simple if you get the inclination correct and then dont touch that. You are then only adjusting the east/west orientation and only 2 variables rather than 4.

Also weight comes into it. I was getting some flex in some angles with my D800E and a 180mm lens. I removed a rubber washer between the screw size adapter I had to use and it stopped it. I now carry a small pair of pliers when I use it to tighten all the tightening screws.


Greg.

[jjjnettie]

I've a spare finder scope that I'm going to rig up as a polar scope. It almost, but not quite fits. Shouldn't be too hard to fix up.
My Polarie is coming with me to the States in May. Looking forward to getting some nice wide fields of the Northern skies and some time lapses over the Grand Canyon. :)

[gregbradley]

Polarie should be really easy to align in the northern hemisphere with Polaris being a relatively bright star and easy to find visually.

A time lapse over the Grand Canyon would be great.

There is a road along the Grand Canyon that goes on for ages. There are plenty of really good views away from the regular ones which are crowded during the day with lots of buses etc. So that may help with setting up.

Greg.

[JB80]

Very much so, I have never had a problem although some say in really dark sky it can be hard to locate. Still it is easy peasy and I have taken note of the methods mentioned here for when I bring mine back South.

[luigi]

YW Greg. Big fan of your images.
I use a red light and move it away from the polarscope end to make it dimmer :D a dimmable red led torch would be great.
The date/hour is for the North Hemisphere.
It's funny but it's actually easier to polar align in the south hemisphere if you have the trapezium in the reticle.



Ioptron's Polar Scope doesn't have the trapezium in the reticle for reasons beyond my understanding.

So to align the Ioptron Sky-Tracker you have to know where to put Sigma Octantis in the polarscope. There's an Iphone/Ipad application for that but I don't have an Iphone or Ipad.

Rant-Starts:
Why oh why did Ioptron decide that it was a good idea for south hemisphere users to carry an iphone/ipad and check it instead of just drawing the trapezium in the reticle?
Rant-Ends:

Ok back to aligning.
Once the trapezium is found (See previous posts/map) then I use an asterism shaped like a J that points towards the South Celestial pole. The asterism points to a small star and then a pair and the SCP is just between them. Center the polarscope on that point and you should be really well aligned with the Ioptron.

If you can't see the "J"/Umbrella then you can just imagine a triangle using the two stars in the shorter side of the trapezium as in map 3 (green).

More tips: Unless your tripod head can rotate you need a panning base for the Ioptron sky-tracker. The Feisol panning base fist perfectly. The Sky-tracker has a latitude control but no azimuth (another design mistery).

Aligning well with the polarscopes takes about 5 minutes or less and you can do 4/5 minutes exposures or even more.

[Octane]

Thanks for your awesome suggestion with the three little stars, Luis.

I get mine tomorrow. Can't wait to play. :)

H

[Phil Hart]

I think you've got most of the advice you need from the rest of this thread.. I have the polar scope and you can certainly do accurate alignment with it from Bendigo skies, but it is over-priced for a polar scope.

Otherwise the combination of an inclinometer and sighting to where Sigma Octans is in the sky is quite accurate.. maybe not quite for 8 mins but with a wide angle lens it could be close.

My TiltBox inclinometer generally gets me within half a degree altitude and I find I can sight to within a degree or two for azimuth as well. Sometimes that's all I do, otherwise that puts Sigma Octans comfortably in the polar scope for final alignment.

Phil

[Hakka]

I got my polar scope, just gave it a try in the middle of bendigo under heavy light pollution. It took about three minutes to get it spot on, without my inclinometer or compass.

To illuminate the scope I used a fenix LED torch with a red filter. I aimed it down the barrel of the scope but it was a bit fiddly as even on the low setting its very powerful. Is there a better way to illuminate the reticule?

[Rohan]

Quick note for an iOptron Skytracker users with android phones. Get the app called PolarFinder. It has an iOptron setting that will match the skytrackers polarscope. Makes accurate alignment much easier once you get the trapezium in the field of view.

As also noted a panning base is a must for the iOptron unless you want to be lifting the whole tripod and moving it.