Help - Polar Scope for EQ3-2 Mount (Skywatcher)

[nheather]

I'll class myself as a beginner that understands science and technology so not totally green.

I have just received a Skywatcher HM5 Polar Alignment Scope for the EQ3-2 Mount and have a few questions

1 - The cardboard box is just slightly wider than the aluminium scale. In transit the box has suffered some very minor squashing which wouldn't normally matter but because there is barely any gap or padding between the box sides and the scale, the scale got slight bent in transit. Now with a little manipulation it is now almost straight (accepting that it is conical before anyone says that I shouldn't have flattened it). I have spoken to the store and they are more than happy to exchange. It would be a fair bit of hassle so my question is -should I bother, would you?

2 - The aluminium scale rotates freely but with some friction around the Polarscope. There doesn't appear to be any means of locking it. Is this correct, should it rotate and if so should you be able to lock it in relation to the rest of the polar scope.

3 - This is fairly well documentated. The polar scope design has changed. The old style polar scope fitted into an eyepiece holder on the mount. Now you have to remove the eyepiece holder and its calendar scale and screw in the new polar scope which comes with its own calendar scale (the one that is slightly bent on mine). No instructions are provided - this isn't a mistake, I think this is what Skaywatcher intends. Skywatcher have published some instructions online but they are for the old style polar scope. I have googled and found plenty of posts many from peopl ewho have given up and returned it. I have managed to removed the old style holder and screw in the new polar scope but I don't really know how to set it up. I can sort of guess from the instruction for the old style but there are differences that I'm unsure about. Can anyone point me in the direction of any good guides.

I have rung up the shop where I bought it and they sound very helpful and suggest that I can return it or bring it in on Tuesday and they will help.

I have also spoken to Optical Vision (the Skywatcher distributers) but to be honest I would have got more help and sense from my mum.

Cheers,

Nigel

[glowjet]

Try Astro_Baby`s Polar aligning instructions, you may be able to resolve some of your issues

[nheather]

Thanks, I have had a look at that. It is quite useful though it does lose me at some points.

The bit where I am confused is that on my polar scope, the date scale just spins round relative to the polarscope. I can't see what effect moving it will have to set up a date relative to the RA scale because the polar scope doesn't move.

I'm thinking the scale should be locked to the polar scope tube so that when the scale turns the polar scope and hence the reticle turns - that would make sense to me.

So either mine is broken or there must be a way of locking the date scale on the polar scope.

Cheers,

Nigel

[nheather]

To clarify, look at this picture.

If I hold the polar scope, the date scale marked with the red arrow freely turns. There doesn't appear to be any way of locking it.

I can't see how that is correct.

Cheers,

Nigel

[JamesF]

That is pretty much how it works. It relies on friction, basically.

At least, mine does.

James

[nheather]

Thanks - so yours rotates aswell?

I'm guessing the only point of it rotating is so that you can set the offset on the secondary scale.

So presumably the set the date by turning the polarscope rather than the dial - so screwing the polarscope in or out of the thread in the mount?

Cheers,

Nigel

[triton1]

Mine also rotates.I don,t bother to align mine perfectly as I only vizualize.Astro babys site will show you

Jonn

[JKB]

Having unscrewed the old mounting and replacing with the PS make sure the thin plastic washer is replaced behind. As said the date ring does move and relies on friction but it should stay pretty well in place when assembled.

From memory I believe you can tighten the 'slip ring' against the date ring too.

HTH

Jamie

[JamesF]

Thanks - so yours rotates aswell?

I'm guessing the only point of it rotating is so that you can set the offset on the secondary scale.

So presumably the set the date by turning the polarscope rather than the dial - so screwing the polarscope in or out of the thread in the mount?

I rotate the disc to align the index mark with the offset on the secondary scale, as you say. I then rotate the entire RA axis to align the date with the time on the time ring. The disc should stay in the right place for that.

James

[glowjet]

Nigel, if you are still having problems and want a reasonably quick Polar align, without a lot of head scratching and scale setting, try this... If your Polar scope will turn fairly smoothly without any looseness or wobble in the threads after backing off for 360° from being screwed home, with the cross hairs also having been centred on the optical axis. You could use the Losmandy Polar aligning method, this is published in their user manual for the GM8/GM11, available as a PDF I believe.

After going through procedures as for Polar aligning, to the point where you need to set date and time circles, just look up Jason Dales Polar Finder program for the time you want to observe, note or copy the angle that is made with Polaris passing through the NCP. Looking through your Polar scope back it off till it mimics the same angle, then with Polaris on the cross hairs slot into the little circle by adjusting the Alt/Az of your mount, job done. Cognisance should always be made of the correct direction you are moving the mount, it should be remembered that Polaris always lies on a line passing through the NCP pointing, to all intents and purposes, in the general direction of Kochab Beta Ursa Min. You will see this on any good quality star map

[nheather]

Having unscrewed the old mounting and replacing with the PS make sure the thin plastic washer is replaced behind. As said the date ring does move and relies on friction but it should stay pretty well in place when assembled.

Thanks, I would have never spotted the washer.

Now my next question - behind my existing mount there are a total of 5 thin plastic washers.

Any idea why?

I'm wondering whether you are supposed to insert the number required so that the crosshair is aligned correctly for midnight when screwed fully home. What do you think?

I have also found how to lock the scale.

There is a collar immediataly behind the scale with an indicator line. This has a grub screw which if unscrewed allows the collar to be rotated - this doesn't held on it's own thow.

Behind this collar is another wider collar which screws on and off.

So if you loosen the thin collar, you can screw in the wider collar to clamp the scale so that it doesn't rotate.

So basically, if you aren't going to change your meridian, you can clamp it to the desired setting. If you do anticipate moving around you can leave it to rotate.

Cheers,

Nigel