Quick polar alignment question

[Peco4321]

Quick one about my alignment process as the results vary quite a lot. Eq3-2 with dual motors and skywatcher 150p, I usually set up the tripod with mount on it and peer through the polar reticule, moving it until i can just about see pole star. Then I put the scope and weight bar on and try and get the pole star centre of the 25mm ep tweaking the mount RA and Dec adjustments. Then centre the finder scope and off I go. 

The problem is that sometimes I'm bang on and have been able to get 1 min exposures  but other times I struggle even at 15 secs. 

Any tips or pointers would be appreciated. Thanks. 

Peter. 

[ronin]

I suspect the problem is 2 fold.

When you add the scope and weights then something will alter slightly, being mechanics it has to move the qusetion being by how much. The second bit is the 25mm eyepiece is, I presume, in the scope and is irrelevant to poalr alignment. So when you go "tweeking" the RA and Dec you are moving the mount off of the polar alignment that you had likely set up and was better. Looking through the scope is irrelevant to polar alignment.

If I recall then you cannot use the poalr scope with the scope and everything on?? Doesn't the weight bar block off where the polar scope goes ? If so all you can do is add the scope and weights carefully and get on with it. Just do not alter it by looking through the scope.

[michael8554]

Hi Peter,

To image without guiding you will need to refine your polar alignment by Drift Alignment.

As ronin has said, adding weight to your mount will alter things to a degree, so Drift with your 1100D attached, using the magnified LiveView image, or the DARV method.

Michael

[wimvb]

On the eq3, the counter weight shaft is fixed, and will not block the polar scope view. Otoh, as said by others, adding the weights and scope will definitely shift the polar alignment. With my eq3, I assemble everything, then put the scope (dec) in a horzontal position from the park position. This will give some headroom to view through the polar scope. Then polar align with the reticle of the polar scope.

If you have the goto version, you can check PA by doing a 2-star goto alignment. Use the handset polar alignment or a drift alignment to refine.

Moving RA or DEC will not affect polar alignment in any way. You can't polar align with RA snd DEC. you need the azimuth and altitude screws to adjust PA.

[Peco4321]

Thanks all. I guess I'm just starting to think in more detail what I'm actually doing and all your comments make perfect sense now. I have seen a few on line video guides for polar alignment and they are often at the ep while making adjustments, but I can now see that really is not doing anything to help. One day, I'll invest in a polar scope, but for now I just need the sky to clear to have a go with all the above in mind. 

Thanks. 

[carastro]

Does you mount work on EQMOd?

Of so, you could use Alignmaster to polar align.  Works well.

Carole 

[wimvb]

Doesn't your mount have a polar scope? I thought it was standard on an eq3.

For drift alignment, you would use an eyepiece (with crosshairs), and use the main scope.

[Peco4321]

Polar scope not standard. About £40 I think. 

[ronin]

They used to be a standard item on the mounts then they stopped that idea and made you buy one - they may still come with the HEQ5 and EQ6 but I think they are not part of the EQ5 kit either. Will warn you that this is from odd bits I read at times and can be totally, completely and utterly wrong. Also maybe one retailer or another may supply a polar scope whereas another does not.

Occasionally they appear used, another is check out Astroboot.

Wim: Always thought that on the EQ3-2 the counter weight bar obstructed the polar scope - there is one where it does (maybe did) and I thought it was that one.

[wimvb]

On my az-eq6 the bar can be pushed in, but on my eq3 pro (= eq3 with goto) it is threaded and screws into the dec axis. My guess is that the mount head is the same for all (skywatcher) eq3 models, but that motors etc are added. I can be wrong of course in this assumption.

[Peco4321]

The weight bar does screw in so no need to screw all the way, thereby leaving a clear view through the reticle. I'll look out for a polar scope 2nd hand. If I was a retailer I would supply eq3-2 with one (obviously build into the price) as it's always easier to justify spending a bit more at the beginning than having to upgrade and keep spending down the line. I have the same thoughts about Raci finder, but each to their own I guess. 

[barkis]

Build yourself a pier for your mount in the garden.
It's not difficult to do, and you can leave the mount attached so as not to disturb polar alignment once you have 
it correct. There are many ways to polar align, the cheapest is drift alignment, and as good as any other, it just takes patience is all.
When you finish your imaging, or observing sessions, simply remove the OTA and store it away, cover the mount and pier with a weather proof
covering, and tie it down against possible high winds, and Bob's you Uncle. No more alignment hassle.
If you don't have a garden, then sorry, this won't help .

 

[Peco4321]

36 minutes ago, barkis said:

If you don't have a garden, then sorry, this won't help

I do, but I also have a football mad 9 year old!!  All my set up goes in the shed after each outing. 

[barkis]

1 hour ago, Peco4321 said:

I do, but I also have a football mad 9 year old!!  All my set up goes in the shed after each outing. 

I understand, I wouldn't like to see the lad deprived of his training ground either.
Perhaps you will reconsider in a few years,  when He has signed for Leeds United, or another Yorkshire Club .

[Peco4321]

2 hours ago, barkis said:

or another Yorkshire Club .

It's Hull City all he way with my lad. We're off on Saturday actually against West Ham. ⚽️⚽️

[barkis]

2 hours ago, Peco4321 said:

It's Hull City all he way with my lad. We're off on Saturday actually against West Ham. ⚽️⚽️

Hope you get a result, Hull City certainly need  points to stay   in the Premier League. It will be a tough  ask, the Hammers  need the points too. 

[Peco4321]

I now have a polar scope, and it has only cost me a donation to a charity from the sender, this hobby never fails to amaze me with its members generosity and feeling of comradery. Anyway I have watched a few on line videos on cantering and frankly, they baffled me. Then I found this and bingo:

http://www.myastroscience.com/polarscopecalibration

Hopefully clear later so will test for real.