Problems with Celestron CG5 polar scope - help please

[Martin-Devon]

Although the CGEM has AllStar align, I wanted to see if I could get more accurate and faster polar alignment by using the Celestron CG5 polar scope in my CGEM (it threads in fine).

It arrived this morning and so far I have nothing but problems with it. Firstly there are no instructions whatsoever, which I think is very poor of Celestron. You have to go to their website to download a sheet which tells you how to calibrate the polar scope first before use - this is a critical step. Next I find that the reticule with Cassiopeia, Ursa Major etc is completely out of focus and that screwing the eyepiece in & out makes no difference to the focus. Because of this it's virtually impossible to see the central circle where you have to position Polaris. There's also bucket loads of grease inside (I have no idea why Celestron do this) so I cleaned the reticule with the Baader wonder cleaning fluid incase there was a film of grease over the reticule, but it made no difference. Lastly, after about 2 hours of trying, I found it just impossible to align and move the reticule to calibrate it following the downloaded instructions. The grub screws to do this are absolutely tiny, making it virtually impossible to use, and everytime I moved a screw inwards it just fell inside the tube and I had to rescue it. Not one of Celestron's better products....

If anybody has any words of wisdom/tips on how I can get focus and calibration of this polar scope I'd like to hear please.

Thanks,

Martin

[Deneb]

Well I have no problem with the Celestron Polar Scope, the way I set up the scope was the following, during the daylight:

Before inserting the polarscope into the mount, I took the polar scope apart (undoing the outer rings so I could adjust the grub screws. If you remove the reticle & smooth of some of the grease, so its not that sticky.

Inside of the polarscope as you can see you have the reticle showing the asterisms held in place by the 3 outer grub screws, buy shining a light down it you can see if all sides are equal, if not adjust the grub screws so the reticle is aligned in the centre.

After screw on the polarscope rings & those setting circles with the polarscope eyepiece, remembering not to screw it on too tight as you will have to use the eyepiece to focus polaris into view.

Nadeem.

[yesyes]

I'm using this polar scope in my CG5. I have to agree that this is not one of Celeston's proudest products. The reticule comes completely loose inside if you loosen the grub screws a little too much. Luckily that adjustment only needs to be done once.

Regarding focus, this is probably quite difficult to simultaneously focus on the very close reticule AND on infinity (Polaris) at the same time. So one of them will always be (slightly) out of focus. I find it helps to shine a red torch in from the top opening while looking through the polar scope. Don't shine it directly in but let it reflect off the side so that you only get a little bit of light. This illuminates the engraving on the reticule while still allowing Polaris to shine through...

[CarlLydon]

You can get the view and the reticle to be in focus at the same time.

The scope has 3 parts threaded together: the eyepiece lens is on one end, and threads into the middle tube that contains the reticle, which in turn is threaded into a longer barrel that has the objective on the other end.

Turn the eyepiece to get the reticle in focus. Don't worry about the view when doing this; it will be blurry. When you have the reticle in focus, loosen the retaining ring that prevents the objective barrel from threading /turning any closer to the front. Thread the ring so it's all the way to the back so the objective barrel can turn freely. Turn the barrel while looking at an object in the distance and get the view sharp. When the view is sharp, thread the retaining ring back to prevent the barrel from turning further.

if you do this you should then have the view and the reticle in focus.

I ended up taking the 3 parts apart to wipe off some of the grease and to help me eyeball center the reticle, that helped.

[BEYOND EARTH]

Martin-Devon,

I'm having all the same problems as well. My main problem are the grub screws! But I was watching a video some time back and found out a very helpful trick. I don't know the size of the grub screw but what I did was take one of my finder scopes and removed the the adjustment screws and replaced them with the grub screws, they fit like a glove. This way you can adjust your polar scope as you would your finder. Heres the video.

Hope this helps!

Be.

[Alan_B]

Does anyone know what size the grub screws are?

I had similar problems with mine and had to dissassemble it as the screw fell in. It would be much easier if you could replace the screws with ones with knurled heads like this

[BEYOND EARTH]

All I know is you cant find them at a hardware store

[Squagnut]

Hmm. The point of the grub screws is that, as Yesyes said, centring the reticule need be done only once.

[bigal1]

I gotta say that i used the tips provided in the video link a while back and replacing the grub screws made a huge difference and allowed me for the first time to get it calibrated perfectly well worth it imo .

[Polar Bear]

The youtube video has some useful tips , especially the 'O' ring behind the EP as this takes a lot of slack out.

Additionally when I came to do my EQ4 the 'O' ring inside the tube had gone hard (12 years old when I got it) and replacing this made a huge difference.

Paul

[James4]

Plan B - remove the Polar Scope - look up the empty housing and put polaris bang in the middle. Your alignment is then within half a degree of true. This is potentially more accurate than if your polar scope is miscollimated or you get the orientation wrong. Then use all-star alignment (now on the CG5 too) if you need to refine it for photography.

[cpartsenidis]

This might be an old topic but I just purchased a Polar scope for my CGEM.

My problem is that while I was "playing" with the grub screws to try and center the reticule, I'm afraid that the reticule accidentally rotated. I believe that this effectively means that when I now screw the polar scope inside the CGEM mount, the big dipper and cassiopeia will not be at the correct place.

My question is how can I make sure the reticule is rotated correctly, so that when the polar scope is fully scewed in to the mount, the diagrams on the reticule are properly aligned with the sky?

Any help or suggestions is really appreciated.

Many thanks,

Chris.

[PDW]

This might be an old topic but I just purchased a Polar scope for my CGEM.

My problem is that while I was "playing" with the grub screws to try and center the reticule, I'm afraid that the reticule accidentally rotated. I believe that this effectively means that when I now screw the polar scope inside the CGEM mount, the big dipper and cassiopeia will not be at the correct place.

My question is how can I make sure the reticule is rotated correctly, so that when the polar scope is fully scewed in to the mount, the diagrams on the reticule are properly aligned with the sky?

Any help or suggestions is really appreciated.

Many thanks,

Chris.

Those diagrams on the reticle are just iconic symbols - they don´t actually line up with any constellation.

http://www.nightskyimages.co.uk/polar_alignment.htm

There are a few web pages that take you through the polar alignment procedure - this is one I found useful.

[cpartsenidis]

Thanks for the reply PDW! I actually managed to align the polarscope, as best as I could, but I'll surely go through the link you kindly provided. Cheers.

[CarlLydon]

I ended up not using the polar scope. It's much to hard to align and the CGEM polar alignment assistance works much better.

[usingen1]

Any tips for aligning the polar finder with a avx mount ?? IU have similar problems like you guys with the CGEM

 

[Donkeiller]

I've got a GC5. Spent hours with the damn Polarscope, getting nowhere. Completely useless. Never managed to get it aligned.

Took the thing out, just eyeball Polaris- which is alot easier to find without the useless Polarscope.

Then use the 3-star align. Seems to work OK and cut down on the swearing!

[usingen1]

I guess that by alignment you mean that the contellations you see (etched in the lens) keep staying upside down or close to, ...this cannot be changed and you need to wait till they align by themselves then do the polar alignment (Polaris) no one tells you but this really only good if the mount stays in place or you can set up exactly the same location, altitude and direction each time you use it - if i knew this beforehand i would have saved a few euro's - if anyone else can contribute to this , please do !