Problems installing polarscope

[Tom123]

Hi,

I've just bought a new EQ5 polarscope for my CG-5 Goto mount which is supposed to be compatible.

However, when I came to installing it I found a major problem in trying to remove the current blank barrel. I've managed to remove the outer RA Circle and the two outer rings, but I cannot remove the inner barrel which appears to be stuck.

To me, it looks like the inner barrel is meant for something else like a another polar finder (but it's too small for the one I have) as it has three adjusting screws and three soft pads just inside the tube.

I am reluctant to take a hammer to it yet, but am prepared to resort to other measures if necessary. But before I do, am I missing something?

Cheers

Tom

[philsail1]

Tom,

I had a Polar scope in my CG5 mount. The whole assembly screws anti clockwise out of the mount. It can be a bit stiff to get it to turn at first. (I gripped mine with a cloth and give it a sharp twist anti clockwise and it freed itself to turn.

Here are some photos - You can just see the three "pads" in the third photo.

Regards,

Philsail1

[SpookyKatt]

Well I have an EQ5 and I fiited a skywatcher polarscope to it but I had to remove the old housing by screwing it out and screwing the new one in as it was a sealed all in one unit.

(Forgive the plastic tubing, I added to make the date circle slightly stiffer to move)

Kathleen

[Tom123]

Hi,

Thank you very much for your help.

Worked a treat....

Cheers

Tom

[philsail1]

Glad it worked out OK Tom!

Regards,

philsail1

[Dreek]

Well, I know this is an old thread, but thankyou!

I've just spent the whole evening surfing around trying to work out whether I should lean on my EQ3-2 polarscope mount to remove it, and the pictures in this thread gave me the confidence to get the stilsons and a towel on it and hey presto...! Job done.

This is the best solution for this problem available so thanks Tom123, philsail1 and SpookyKat.

Dreek

[Peter2013]

Hi,

I also have an Skywatcher EQ5 and I have a polarscope installed, but I am not sure that it is rotated in the right direction. My issue is that when I set the small circle to the lowest position, my counter-weight shaft is not pointing downwards, but in an angle (to vertical). An when I do the polar alignment, my tube (200/1000) is looking weird. I wonder if I should loosen it and set it. Or is it not necessary? What is the right setting?

Cheers: Peter

[JamesF]

The position  of the polar scope is irrelevant to the position of the OTA or the counterweights.

The first thing to do is to check that it is aligned with the RA axis.  Without the OTA or counterweights, point the polar scope at some fixed mark during the day.  The meeting of two parts of a television aerial would be useful.  If the centre-marker of the polar scope stays pointing at that position when you rotate the RA axis you're good.  If it appears to move then you need to realign.

Once that's done you need to set the correct rotation for the reticle.  The easiest way to do that is (again, during the day) to set the rings to midnight on 1st November.  At that time and date the Polaris indicator should be right at the bottom of the reticle.  If it isn't then you'll also need to adjust that.

This is for the HEQ5, but it's the procedure I've followed for all my mounts, so it should work for you:

http://www.astro-baby.com/HEQ5/HEQ5-1.htm

The only change I make is to use midnight on the 1st November to set the position of the Polaris indicator rather than today's date and time, when Polaris could be anywhere.

James

[Peter2013]

Thank you James, but I think it is relevant. Why do I think that? The movement around the RA axis is limited, it is about 180 degress. If in a polar aligned home position it is in the middle (the counterweight shaft points down), then you can move 90 degrees to the left and 90 degrees to the right. But if it is not, then you can move less into a direction, e.g. 60 degrees to the left and 120 degrees to the right. Would it not be a problem? Say you want to find an object, you start the tracking (I have GoTo also) but you reach your limit before you reach the desired position of the object.

I am aware of how to align the polarscope with the 3 screws, but that is rather how to move the reticule in the tube of the polar scope, not how to rotate the reticule.

Cheers: Peter

[JamesF]

The counterweight always points down in the home position.  That does not mean (usually absolutely will not mean) that Polaris appears in the Polaris indicator at the same time, even if the mount is polar aligned.  The two are not related.  Polaris is only at the indicated position (when the mount is properly polar aligned) when the time and date on the rings is set correctly.  At that point the counterweight bar might point anywhere.

I don't understand why you only have 90 degrees of travel each way in the RA axis.  Without a scope on board all my mounts will rotate 360 degrees as long as I move the DEC axis so it can't foul the mount body at the bottom of its travel.

James

[Peter2013]

I will check it next time I use it, but I will definitely not be able to turn it 360 degrees, because one of the cables will not let it happen (the one that connects DE in and DE out).

Peter

[JamesF]

Ah, because of the cable length and/or routing?

No reason you couldn't disconnect that for polar alignment.  The mount wouldn't need to be powered up.

Or you could just get Polaris somewhere in the centre of the reticle and from that point use a camera to drift align (or use eqalign etc.)

James

[Peter2013]

Thinking about it again it really does not matter where the little circle is. Once the RA axis is polar aligned, I can turn it anywhere. It was just so confusing.

But the tube needs to be in the home position before I turn on the SynScan unit, right? So the tube has to be polar aligned, right? Then I can start the 1, 2 or 3 star alignment process.

Cheers: Peter

[JamesF]

You don't really need polar alignment if you're going to use the Synscan star alignment procedure.  Initially I just used to plonk the mount down pointing roughly north and then do a three-star align and it was never too far off for finding targets.  It's when you're imaging that the polar alignment really counts.

It probably makes life easier if you have the mount in the home position when starting up and powering off.  I'm not at all sure it's strictly necessary.

James